Quantum depolarizing channel

A quantum depolarizing channel is a model for quantum noise in quantum systems. The formula_1-dimensional depolarizing channel can be viewed as a completely positive trace-preserving map formula_2, depending on one parameter formula_3, which maps a state formula_4 onto a linear combination of itself and the maximally mixed state,
The condition of complete positivity requires formula_3 to satisfy the bounds
Qubit Channel.
The single qubit depolarizing channel has operator-sum representation on a density matrix formula_4 given by
where formula_10 are the Kraus operators given by
and formula_12 are the Pauli matrices. The trace preserving condition is satisfied by the fact that formula_13
Geometrically the depolarizing channel formula_2 can be interpreted as a uniform contraction of the Bloch sphere, parameterized by formula_15. In the case where formula_16 the channel returns the maximally-mixed state for any input state formula_4, which corresponds of the complete contraction of the Bloch-sphere down to the single-point formula_18 given by the origin.
Classical capacity.
The HSW theorem states that the classical capacity of a quantum channel formula_19 can be characterized as its regularized Holevo information:
This quantity is difficult to compute and this reflects our ignorance on quantum channels. However, if the Holevo information is additive for a channel formula_19, i.e.,
Then we can get its classical capacity by computing the Holevo information of the channel.
The additivity of Holevo information for all channels was a famous open conjecture in quantum information theory, but it is now known that this conjecture doesn't hold in general. This was proved by showing that the additivity of minimum output entropy for all channels doesn't hold, which is an equivalent conjecture.
Nonetheless, the additivity of the Holevo information is shown to hold for the quantum depolarizing channel, and an outline of the proof is given below. As a consequence, entanglement across multiple uses of the channel cannot increase the classical capacity. In this sense, the channel behaves like a classical channel. To achieve the optimal rate of communication, it suffices to choose an orthonormal basis to encode the message, and perform measurements that project onto to the same basis at the receiving end.
Outline of the proof of the additivity of Holevo information.
The additivity of Holevo information for the depolarizing channel was proved by Christopher King. He showed that the maximum output p-norm of the depolarizing channel is multiplicative, which implied the additivity of the minimum output entropy, which is equivalent to the additivity of the Holevo information.
A stronger version of the additivity of the Holevo information is shown for the depolarizing channel formula_2. For any channel formula_19:
This is implied by the following multiplicativity of maximum output p-norm (denoted as formula_26):
The greater than or equal to direction of the above is trivial, it suffices to take the tensor product the states that achieve the maximum p-norm for formula_2 and formula_19 respectively, and input the product state into the product channel to get the output p-norm formula_30. The proof for the other direction is more involved
The main idea of the proof is to rewrite the depolarizing channel as a convex combination of simpler channels, and use properties of those simpler channels to get the multiplicativity of the maximum output p-norm for the depolarizing channel.
It turns out that we can write the depolarizing channel as follows:
where formula_32's are positive numbers, formula_33's are unitary matrices, formula_34's are some dephasing channels and formula_4 is an arbitrary input state.
Therefore, the product channel can be written as:
By the convexity and the unitary invariance of the p-norm, it suffices to show the simpler bound:
One important mathematical tool used in the proof of this bound is the Lieb–Thirring inequality, which provides a bound for p-norm of a product of positive matrices. The details and the calculations of the proof are skipped, interested readers are referred to the paper of C. King mentioned above.
Discussion.
The main technique used in this proof, namely rewriting the channel of interest as a convex combination of other simpler channels, is a generalization of the method used earlier to prove similar results for unital qubit channels.
The fact that the classical capacity of the depolarizing channel is equal to the Holevo information of the channel means that we can't really use quantum effects such as entanglement to improve the transmission rate of classical information. In this sense, the depolarizing channel can be treated as a classical channel.
However the fact that the additivity of Holevo information doesn't hold in general proposes some areas of future work, namely finding channels that violates the additivity, in other words, channels that can exploit quantum effects to improve the classical capacity beyond its Holevo information.


Thermodynamic beta

In statistical thermodynamics, thermodynamic beta, also known as coldness, is the reciprocal of the thermodynamic temperature of a system:formula_1 (where is the temperature and is Boltzmann constant). It was originally introduced in 1971 (as "coldness function") by , one of the proponents of the rational thermodynamics school of thought, based on earlier proposals for a "reciprocal temperature" function.
Thermodynamic beta has units reciprocal to that of energy (in SI units, reciprocal joules, formula_2). In non-thermal units, it can also be measured in byte per joule, or more conveniently, gigabyte per nanojoule; 1 K−1 is equivalent to about 13,062 gigabytes per nanojoule; at room temperature: = 300K, β ≈ ≈ ≈ . The conversion factor is 1 GB/nJ = formula_3 J−1.
Description.
Thermodynamic beta is essentially the connection between the information theory and statistical mechanics interpretation of a physical system through its entropy and the thermodynamics associated with its energy. It expresses the response of entropy to an increase in energy. If a system is challenged with a small amount of energy, then "β" describes the amount the system will randomize.
Via the statistical definition of temperature as a function of entropy, the coldness function can be calculated in the microcanonical ensemble from the formula
(i.e., the partial derivative of the entropy with respect to the energy at constant volume and particle number ).
Advantages.
Though completely equivalent in conceptual content to temperature, is generally considered a more fundamental quantity than temperature owing to the phenomenon of negative temperature, in which is continuous as it crosses zero whereas has a singularity.
In addition, has the advantage of being easier to understand causally: If a small amount of heat is added to a system, is the increase in entropy divided by the increase in heat. Temperature is difficult to interpret in the same sense, as it is not possible to "Add entropy" to a system except indirectly, by modifying other quantities such as temperature, volume, or number of particles.
Statistical interpretation.
From the statistical point of view, "β" is a numerical quantity relating two macroscopic systems in equilibrium. The exact formulation is as follows. Consider two systems, 1 and 2, in thermal contact, with respective energies "E"1 and "E"2. We assume "E"1 + "E"2 = some constant "E". The number of microstates of each system will be denoted by Ω1 and Ω2. Under our assumptions Ω"i" depends only on "Ei". We also assume that any microstate of system 1 consistent with "E1" can coexist with any microstate of system 2 consistent with "E2". Thus, the number of microstates for the combined system is
We will derive "β" from the fundamental assumption of statistical mechanics:
(In other words, the system naturally seeks the maximum number of microstates.) Therefore, at equilibrium,
But "E"1 + "E"2 = "E" implies
So
i.e.
The above relation motivates a definition of "β":
Connection of statistical view with thermodynamic view.
When two systems are in equilibrium, they have the same thermodynamic temperature "T". Thus intuitively, one would expect "β" (as defined via microstates) to be related to "T" in some way. This link is provided by Boltzmann's fundamental assumption written as
where "k"B is the Boltzmann constant, "S" is the classical thermodynamic entropy, and Ω is the number of microstates. So
Substituting into the definition of "β" from the statistical definition above gives
Comparing with thermodynamic formula
we have
where formula_16 is called the "fundamental temperature" of the system, and has units of energy.


Indian Journal of Physics

The Indian Journal of Physics is a monthly peer-reviewed scientific journal published by Springer Science+Business Media on behalf of the Indian Association for the Cultivation of Science. It was established in 1926 by C. V. Raman and covers applied, experimental, and theoretical physics. The editor-in-chief is Subham Majumdar.
Abstracting and indexing.
The journal is abstracted and indexed in:
According to the "Journal Citation Reports", the "Indian Journal of Physics" had a 2016 impact factor of 0.988.


Alain Benoit

Alain Benoit (born 1948) is a French physicist specialising in low temperature physics. He was awarded the CNRS silver medal in 1993 and the CNRS innovation medal in 2012.
He is a research director at the Grenoble Very Low Temperature Centre, where he contributed to the cooling of the European Space Agency's Planck telescope to 0.1 K. He was elected a member of the French Academy of Sciences in 2002.


Korean Physical Society

The Korean Physical Society is a non-profit scientific society created to provide a forum for academic exchange among scholars and researchers in the field of Physics.
The organization, was founded in Busan(formerly Pusan) in 1952 during the Korean War. In 2020, membership levels were around 15,000. Within the organization, there are twelve topic-specific divisions, including Particle and Field Physics, Atomic and Molecular Physics, and Astrophysics.
The society publishes several journals, including its flagship "Journal of the Korean Physical Society", published by Springer Publishing. The journal covers all fields of physics, ranging from statistical physics and condensed matter physics to particle physics.
The Korean Physical Society has Memorandums of Understanding (MOUs) with several other scientific associations, including the Japan Society of Applied Physics and the American Physical Society.


Matthias Staudacher

Matthias Staudacher is a German theoretical physicist who has done significant work in the area of quantum field theory.
Education.
Beginning his physics studies at the University of Heidelberg and at Ludwig Maximilian University of Munich, Staudacher then earned a Ph.D. at the University of Illinois at Urbana-Champaign (1990) with a dissertation on matrix models of two-dimensional quantum gravity.
After postdoctoral work at Rutgers University in New Jersey, Paris and CERN in Geneva, from 1997 he was a researcher at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam. In 2009 he received the Academy Award of the Berlin-Brandenburg Academy of Sciences and Humanities and became a mathematical physics professor at Humboldt University of Berlin in 2010. Some of his publications have been instrumental in developing an understanding of the so-called AdS/CFT correspondence, a duality between the Yang-Mills-type quantum theory and supersymmetric string theory first suggested in the 1990s by Juan Martín Maldacena. Staudacher suggests that the integrable spin chains of condensed matter physics may form the link between the two approaches.


George Kalmus

George Ernest Kalmus, CBE, FRS (born 21 April 1935) is a noted British particle physicist.
Kalmus was born in Beočin, Yugoslavia, and moved to Britain with his parents and his elder brother Peter Kalmus in 1939. His sister Elsa Joan Kalmus was born in 1945. The family became British Citizens in 1946.
Kalmus was Associate Director, 1986–94 and Director of Particle Physics, 1994–97 at the Rutherford Appleton Laboratory.
He was Visiting Professor, Physics and Astronomy Department, 1984–2000, University College London and has been a Fellow there since 1998.
Kalmus was elected a Fellow of the Royal Society in 1988 and made a CBE in 2000.
He is currently an Honorary Scientist, Rutherford Appleton Laboratory
Education.
Kalmus went to school first in Hampstead and then in Harpenden, Hertfordshire. From 1945 till 1953 he was at St Albans County Grammar School (later renamed Verulam School). He received his BSc (1956) and PhD (1959) at University College London[1] where he remained for a further three years as a Research Associate. He is now an Honorary Fellow of University College London.[1]
Career and selected research.
Kalmus undertook his PhD at University College London, working with the bubble chamber group. The UCL group was working with the only heavy liquid chamber in the UK, the other groups being based on liquid hydrogen or helium chambers. The aim of the group was to investigate ways of operating so-called "heavy liquids" at temperatures close to room temperature, and in particular to investigate the use of various high Z (atomic number) liquids as possible bubble chamber fluids.
After graduation, Kalmus continued at University College London, working on the design of a large bubble chamber which was built by the UCL group for the newly established National Institute for Research in Nuclear Science (NIRNS) – later to become the Rutherford Laboratory, and subsequently the Rutherford Appleton Laboratory (RAL). The University College London group's contribution was to design a 1.4m heavy liquid bubble chamber, as one of the suite of tools to be used at the NIRNS 7GeV proton synchrotron.
Apart from this design work, the University College London group also established a collaboration with the heavy liquid bubble chamber group led by Professor Wilson Powell and Dr Bob Birge at the [Lawrence Radiation Laboratory] in Berkeley, California. Kalmus participated in experiments to measure the branching ratio of the rare decay of the lambda hyperon into a proton, electron and anti neutrino used a stopping Kplus beam and from 230000 pictures obtained some 150 events of the above kind out of 190000 lambdas decaying to proton piminus. Kalmus maintained a lasting interest in this field throughout his career.
In 1962, Kalmus joined the Powell-Birge group at the Lawrence Radiation Laboratory (LRL), initially working on a stopped K+ meson decay exposure in the 30 inch bubble chamber. Apart from a brief return to University College London circa 1964, Kalmus remained at the Lawrence Radiation Laboratory until 1971, participating in a systematic investigation of Kminus proton scattering in the resonance region.
In 1970, Kalmus spent a year of sabbatical leave at CERN and there joined the Fidecaro group who were working on a pi+ proton scattering experiment on a polarised proton target using an electronic detector.
In 1971, Kalmus became the head of the bubble chamber group at the Rutherford Laboratory (subsequently the Rutherford Appleton Laboratory from 1979 onwards). This was a large group, and Kalmus became responsible for leading its research direction. At that time, The Rutherford Laboratory housed a 7 GeV weak focusing Proton Synchrotron, and an accelerator very similar to the Bevatron used at the Lawrence Radiation Laboratory in Berkeley. The CERN proton synchrotron, a 25 GeV strong focusing machine, was already in operation and it was clear that most experiments, including those at low energies using secondary beams, were better performed at CERN. Kalmus organised the Rutherford Laboratory group into three areas, led by Colin Fisher, Wilbur Venus and by Kalmus himself. All three research streams had very strong UK and International collaborations. The groups were involved in a number of experiments using the CERN proton synchrotron (PS) and later the CERN Super Proton Synchrotron (SPS)(see NA26, WA24, WA30, WA59 in particular in the List of Super Proton Synchrotron experiments).
Kalmus firmly believed in the concept that the Rutherford Appleton Laboratory, as the National Laboratory for Particle Physics, had as an important part of its mission the support of UK university groups. He encouraged collaboration by working with university groups on all his experiments. Because RAL staff had no teaching responsibilities, they were more able to take on work within the collaborations that required longer periods at CERN or other overseas accelerators.
In 1978, based on the success of the track sensitive target neutrino programme spearheaded by Wilbur Venus, Kalmus proposed an experiment using this equipment, but instead of a neutrino beam, used a 70 GeV negative pion beam. The idea being that the primary interaction would take place in the hydrogen, and the reaction products would then traverse the surrounding Neon-Hydrogen mixture and electrons would be easily identified. This experiment was approved as a collaboration between the Rutherford Appleton Laboratory group and groups from Glasgow, Bologna, Saclay and Torino. The results strengthened the evidence for single electrons apparently emerging from primary interaction vertices.
This was followed by an experiment he proposed which ran between 1979 and 1982 to measure the lifetimes of the charged and neutral charmed mesons using facilities at SLAC, as a collaboration with groups from Birmingham under Derek Colley, Imperial College under Peter Dornan, and groups from the US and Japan. This was to be Kalmus’ last bubble chamber experiment. The bubble chamber technique was increasingly having to be extended and enhanced in order to produce competitive results. By the mid 1980s all bubble chambers had been closed. Kalmus was nevertheless a significant practitioner for much of the thirty-year period when the bubble chamber was the dominant technique in the field.
Kalmus’ group then turned to the Large Electron–Positron Collider (LEP) being constructed at CERN. The three sub groups of the bubble chamber group re coalesced and joined with groups from Oxford, and later Liverpool, the newly forming international collaboration, which eventually became DELPHI. DELPHI – standing for DEtector with Lepton, Photon and Hadron Identification – was one of four large detectors used at LEP.
In 1986, Kalmus was asked to become the Director of Particle Physics and Head of the Particle Physics Department at the Rutherford Appleton Laboratory, remaining in that position and capacity until 1997. This work took him away from much of the direct research participation, but established Kalmus as a highly influential figure nationally and internationally.
He also subsequently became the chairman of the DELPHI collaboration board and deputy spokesperson. The UK responsibility within the DELPHI project was in three technical areas: the outer detector, primarily Liverpool; the barrel muon chambers, primarily Oxford; and the data acquisition system, primarily RAL. However, the UK groups were centrally funded, and RAL with its relatively large engineering and design capabilities participated in all three activities when need arose. The Rutherford Appleton Laboratory also designed and constructed the large super conducting solenoid which surrounded the DELPHI detector.
In 1998, Kalmus took sabbatical leave from the Rutherford Appleton Laboratory and joined the NA48 Experiment at CERN whose prime purpose was to measure "direct" CP violation in Kzero decays. Since RAL was not a formal participant in the experiment, Kalmus joined the group from Cambridge led by Dr Tom White, who together with a small group from Edinburgh were the British members of the collaboration.
Kalmus formally retired from the Rutherford Appleton Laboratory in 2000, but remains an Honorary Scientist there.
Subsequent to his retirement, he joined the ZEPLIN 3 collaboration (RAL, Imperial College, Edinburgh, and Russian and Portuguese groups) searching for 'Dark Matter' particles, using a liquid xenon detector located down the Boulby Potash mine in Yorkshire.
Publications.
Kalmus has published numerous articles on experimental particle physics. A listing of many of Kalmus' works can be found in 'INSPIRE' Particle Physics Database and the Science and Technology Facilities Council ePublication Archive.
Professional and science organisations.
Kalmus has served on and contributed to a considerable number of professional and science organisations throughout his career. These have included over a decade as the Director and Head of Particle Physics Department of the Rutherford Appleton Laboratory. Kalmus has also been an active member of the Lawrence Radiation Laboratory and of CERN and University College London.
He has also been involved the Royal Society and with the American Physical Society and the Institute of Physics.
Apart from his duties as Director of Particle Physics at Rutherford Appleton Laboratory, Kalmus has served on a number of international committees. These include:
Personal life.
Kalmus' father, Hans Kalmus, was a well-known biologist who worked at University College, London from 1939, officially retiring as Professor in 1973 but continuing there until his death in 1988 at the age of 82.
His brother, Peter Kalmus, is another noted British particle physicist. A press release from the Particle Physics and Astronomy Research Council(PPARC) in 2002 commented that "A particle physicist in the family is a rare occurrence. That there should be two and both be leaders of the field is even more unusual, yet Professors Peter and George Kalmus have achieved this."
Kalmus has three daughters.
He currently resides in Abingdon with his wife, Ann Christine (née Harland) Kalmus.


William Allis

William Phelps Allis (November 15, 1901 – March 5, 1999) was an American theoretical physicist specializing in electrical discharges in gases. He was the grandson of Edward P. Allis, founder of the E.P. Allis Company, which became Allis-Chalmers.
Education.
Allis majored in school and received his S.B. in 1923 and S.M. in 1924 from the Massachusetts Institute of Technology (MIT). He was granted his "Docteur ès science" (Sc.D.) in physics, in 1925, from the University of Nancy, France. From 1925 to 1929, he was a research associate at MIT. It was there that he met Philip M. Morse. Morse, at the suggestion of Karl T. Compton, made arrangements for postdoctoral studies and research with Arnold Sommerfeld at the Ludwig Maximilian University of Munich in 1930 and at the University of Cambridge in the spring and summer of 1931. Allis went with Morse to Munich and Cambridge.
Career.
Upon his return from Europe, Allis was an instructor in physics at MIT from 1931 to 1934. He joined MIT's physics department faculty in 1934 and was appointed full professor in 1950, a position he held until he became professor emeritus in 1967.
During World War II he worked at the MIT Radiation Laboratory conducting research on magnetron theory. He then joined the United States Army where he served in the Liaison Office of the Naval Defense Research Committee. He also participated in Operation Alsos. He achieved the rank of Lieutenant Colonel, and was awarded the Legion of Merit in 1945.
Allis was one of co-founders of the American Physical Society's Gaseous Electronics Conference, for which he served as chairman from 1949 to 1962. On leave from MIT for two years, 1962–1964, he served as assistant secretary-general for scientific affairs for the North Atlantic Treaty Organization (NATO).
Allis directed Project Ashby, which was to determine the feasibility of building a nuclear fusion engine.


R. John Hansman

R. John Hansman is an American physicist currently the T. Wilson Professor of Aeronautics & Astronautics at Massachusetts Institute of Technology and an Elected Fellow of the American Institute of Aeronautics and Astronautics.


Pitot pressure

Pitot pressure is the pressure that is measured by a Pitot tube, an open-ended tube connected to a pressure-measuring device. For subsonic flow, pitot pressure is equal to the stagnation pressure (or total pressure) of the flow, and hence the term pitot pressure is often used interchangeably with these other terms. For supersonic flow, however, pitot pressure is the stagnation pressure of the flow behind the normal shock ahead of the pitot tube. Pitot pressure is named for Henri Pitot, French scientist.


David Lindley (physicist)

David Lindley (born 1956) is a theoretical physicist and author. He holds a B.A. in theoretical physics from Cambridge University (1975 – 1978) and a PhD in astrophysics from the University of Sussex (1978 – 1981). Then he was a postdoctoral researcher at Cambridge University. From 1983 to 1986, he was a Research Fellow in the Theoretical Astrophysics Group at the Fermi National Accelerator Laboratory. He then served as Technical Editor and Writer with the Central Design Group for the Superconducting Supercollider at the Lawrence Berkeley Laboratory in Berkeley, California. He was an Associate Editor at "Nature" (1987 – 1993), a Senior Editor of "Science" (1994 – 1995), and an Associate Editor of "Science News" (1996 – 2000). Since 2000, he is a freelance science writer and consultant.
Lindley is known for writing entertaining scientific texts that show not only great knowledge of physics, but also a wit and understanding of what the layman can grasp. Most of his books explain the scientific theories through the use of a scientist's biography or an historical account of disagreement amongst scientists.
In "The End of Physics", Lindley challenged the assumption that string theorists might achieve a unified theory. He contended that particle physics was in danger of becoming a branch of aesthetics, since these theories could be validated only by subjective criteria, such as elegance and beauty, rather than through experimentation.


Patrick Huerre

Patrick Huerre, born in 1947, is a French physicist in fluid mechanics. An engineer from the École centrale de Paris (1970), and a doctor of aeronautical sciences from Stanford University, he began his career at the University of Southern California in Los Angeles. In 1989, he was appointed Professor of Mechanics at the École polytechnique where he created, with Jean-Marc Chomaz, and then directed the Laboratoire d'hydrodynamique (LadHyX), a joint CNRS-École polytechnique research unit. He is currently Director of Research Emeritus at the Centre national de la recherche scientifique (CNRS). He is a member of the French Academy of Sciences.
Biography.
Training.
He received an engineering degree from the École centrale de Paris in 1970. He then obtained a master's degree and a doctorate in aeronautical sciences from Stanford University (1971, 1976).
Career.
During his PhD (1971-1975), Patrick Huerre was a Research Assistant in the Department of Aeronautics and Astronautics at Stanford University. From 1976 to 1978, he was a postdoctoral fellow with David Crighton in the Department of Applied Mathematics at the University of Leeds. In 1978, he was hired by Janos Laufer as Assistant Professor of Aerospace Engineering at the University of Southern California, Los Angeles. He will then be promoted to Associate Professor and then Professor. In 1989, he returned to France after his appointment as Professor of Mechanics at the École polytechnique, a position he held until 2012. In 1990, he and Jean-Marc Chomaz founded the Hydrodynamics Laboratory (LadHyX), which he managed until 2008. At the same time, from 1991 to 2012, he was Director of Research at the CNRS. He is currently Director of Research Emeritus. He was invited in 2015 as a Professor at the Miller Institute for basic research in science at the University of California at Berkeley.
Scientific work.
Patrick Huerre's theoretical research focuses on fluid dynamics. Most of his work focuses on hydrodynamic instabilities to account for the transition to chaos or turbulence in sheared flows. The configurations studied are, for example, the Bénard-Karman vortex path in the wake of a cylinder or the Kelvin-Helmholtz vortices in the mixing layer separating two parallel flows of different speeds. The use of the concepts of convective/absolute instability allowed him to make a rigorous distinction between amplifier-type and oscillator-type flows.  The introduction, for oscillators, of the notion of linear global mode has thus led to the establishment of frequency selection criteria in very good agreement with the experiments. These concepts were then generalized to the fully non-linear regime. In aero-acoustics, Patrick Huerre has identified super-directiveness as a key concept in the production of aerodynamic noise in sheared flows. Over the past decade, it has characterized the acoustic radiation of global modes present in hot jets and the overall instability properties of plumes. He now turns to the asymptotic analysis of critical baroclinic layers and their role in the generation of "zombie" eddies in proto-planetary disks in astrophysics.


Juan Carlos Campuzano

Juan Carlos Campuzano (born July 25, 1949) is a Paraguayan American physicist. He is a Distinguished Professor of Physics at the University of Illinois at Chicago. He was a Distinguished Fellow at Argonne National Laboratory (the equivalent of an endowed chair), and a he is also a 2001 American Physical Society Fellow and a recipient of the 2011 Oliver Buckley Prize in Condensed Matter Physics.
He is an expert in high-temperature superconductivity.
Campuzano obtained his B.S. and Ph.D. in physics from University of Wisconsin–Milwaukee in 1972 and 1978, respectively. He has also worked as a Post-Doctoral Fellow and Research Associate at the University of Liverpool and the University of Cambridge. His research interests include infrared spectroscopy on metal surfaces, electronic excitations in high temperature superconductors and other materials, etc.


Natalie Roe

Natalie Roe is an experimental particle physicist and observational cosmologist, and the Associate Laboratory Director for Physical Sciences at Lawrence Berkeley National Laboratory (LBNL) since 2020. Previously, she was the Physics Division Director for eight years. She has been awarded as the Fellow of American Physical Society (APS) and American Association for the Advancement of Science (AAAS) for her exceptional scientific career and contributions.
Education.
Roe earned her undergraduate degree in Physics from Harvard University in 1981, and her doctoral degree from Stanford University in 1989. She joined the Lawrence Berkeley National Laboratory as a postdoc in 1989, where she is currently the Associate Laboratory Director for Physical Sciences.
Research career and collaborations.
Roe particle physics research career has included the analysis of subatomic particle properties in accelerator-based experiments at SLAC and Fermi National Accelerator laboratories, and her cosmology research has involved surveys using telescopes based in Arizona, New Mexico, and Chile to study the mystery of dark energy including the Baryon Oscillation Spectroscopic Survey (BOSS), the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI).
She started her career in high energy physics with Professor Carlo Rubbia during her undergrad, which leads her to get a job at CERN for a year on the UA1 experiment. This experience at CERN plays a big impact on her ultimate career path in particle physics. During her PhD, she searched for Anomalous Single Photon at SLAC.
She started as a postdoc at Lawrence Berkeley National Laboratory in 1989 on the D0 experiment at Fermilab. She has a strong interest in instrumentation and has built the electromagnetic calorimeter on the D0 and analyised the production and decay of W and Z bosons at the Fermilab Tevatron, led the design and construction of the Silicon Vertex Tracker for the BaBar experiment at SLAC from 1993 to 2005, and was the Instrument Scientist for the BOSS experiment designed to study the mystery of dark energy. As group leader for the LBNL MicroSystems Laboratory for almost 10 years, she was responsible for the fabrication of the science CCDs for both DES and BOSS.
She has served on many community panels including High Energy Physics Advisory Panel (HEPAP), the National Science Foundation Physics Division Committee of Visitors, the FNAL Physics Advisory Committee (PAC), and the Neutrino Science Advisory Group, and she is a past Chair of the American Physical Society (APS) Division of Particles and Fields. She has also been a member of the International Committee on Future Accelerators (ICFA) from 2007-2009 and the DESY Scientific Council, and served on the CERN Scientific Policy Committee and several other national and international councils.
Natalie is also a founding member of the Berkeley Lab Women Scientists and Engineers Council and is co-leading a laboratory-wide initiative to improve diversity and inclusion at the Lab.
Honors and awards.
Roe has been awarded as American Physical Society Fellow in 2001 for her leadership in the design and construction of the BaBar silicon vertex detector, and her studies of BB mixing, oscillations, and CP violation in B meson decays. In honor of her invaluable contributions to science and technology, she has been awarded as the Fellow of the American Association for the Advancement of Science in 2020.


Blackett Laboratory

The Blackett Laboratory is part of the Imperial College Faculty of Natural Sciences and has housed the Department of Physics at Imperial College London since its completion in 1961. Named after experimental physicist Patrick Blackett who established a laboratory at the college, the building is located on the corner of Prince Consort Road and Queen's Gate, Kensington. The department ranks 11th on QS's 2018 world university rankings.
History.
The Department of Physics at Imperial College dates back to the physics department of the Normal School of Science, later the Royal College of Science. As part of the formation of Imperial, the Royal College was moved into a new building at South Kensington in 1906, which also housed the Chemistry Department. From 1906 to 1932 the head of the Physics Department was Prof. H. L. Callender, famous for his work on the properties of steam.
G P Thomson (son of J J Thomson) replaced Callender in 1932, and worked in part on nuclear physics and atomic weaponry. He was followed P. M. S. Blackett as head in around 1953, with the construction of the new Physics building starting at about the same time. Blackett refocused efforts from low-energy physics to high-energy nuclear physics, and under him research started into cosmic rays and the use of bubble chambers, with the first liquid hydrogen bubble chamber in Western Europe being constructed at the department. Work on satellite instrumentation resulted in departmentally designed equipment ending up on NASA satellites in 1962. Physics continued in the new “old” RCS building until the new Physics building was finished in 1961, which subsequently became known as the Blackett Laboratory. In 2019, it was announced that the laboratory would be constructing a magnetometer instrument for the European Space Agency Solar Orbiter in a mission to study the Sun. The satellite launched on an Atlas V from the Cape Canaveral AFS, Florida on the 9 February, 2020. In November 2019, a team of Imperial physicists was chosen to design parts of the Deep Underground Neutrino Experiment, which is to be a long baseline accelerator neutrino experiment in the United States.
Academics.
Study.
Undergraduate.
The department offers three year BSc and four year undergraduate MSci courses. The department has connections with universities in Europe, allowing undergraduate master's students to study-abroad during their course. All students graduating with an undergraduate degree from the department are also awarded the Associateship of the Royal College of Science, ARCS. This degree is professionally accredited by the Institute of Physics. Holders of accredited degrees can follow a route to Institute Membership and the CPhys professional qualification.
Postgraduate.
Taught postgraduate courses last for one year leading to a MSc, with research degrees leading to either a MRes or PhD. All students graduating with any of the postgraduate degrees (MSc, MRes, PhD) are also awarded the Diploma of Imperial College, DIC. There are also a number of short-courses for practising engineers.
Rankings.
The college ranks 9th on the Times Higher Education natural sciences subjects rankings, and the department in particular ranks 11th in the world, and 3rd in the UK after Cambridge and Oxford, on the QS World University Rankings. Domestically, the department ranks 6th in the Complete University Guide's 2021 physics rankings.
People.
The laboratory has connections to many physicists who had studied or taught at the department:


Yerevan Physics Institute

The A.I. Alikhanyan National Science Laboratory () is a research institute located in Yerevan, Armenia. It was founded in 1943 as a branch of the Yerevan State University by brothers Abram Alikhanov and Artem Alikhanian. It was often referred to by the acronym YerPhI (Yerevan Physics Institute). In 2011 it was renamed to its current name A.I. Alikhanyan National Science Laboratory.
History and strategy.
The Yerevan Physics Institute was founded in 1943 as a branch of the Yerevan State University by brothers Abraham Alikhanov and Artem Alikhanian. Later two high-altitude cosmic ray stations were founded on Mount Aragats (3,200 m) and Nor Amberd (2,000 m).
In 1963 the institute was transferred to the Soviet Union Atomic Energy State Committee. The construction of a 6 GeV electron synchrotron accomplished in 1967 became an important landmark in the history of institute, it is the first particle accelerator in Armenia (Arus "ԱՐՈՒՍ"). After collapse of Soviet Union YerPhI continued research in the fields of high-energy physics and astrophysics in Armenia and worldwide using world biggest accelerators and cosmic ray detectors. Now YerPhI get status of A. Alikhanyan National Laboratory.
Brief summary of scientific activities.
Among the key results of YerPhI in the early years were the discovery of protons and neutrons in cosmic rays, and the establishment of the first evidence of existence of the particles with masses between that of muons and protons. The high altitude research stations have remained the main research base of the Cosmic Ray Division (CRD) of YerPhI until now. Among the CRD achievements there were: discovery of sharp knee in light components of primary cosmic rays, detection of the highest energy protons accelerated on the Sun, and the creation of the Aragats Space environ¬mental Center in 2000 for studies of the solar-terrestrial connection, where CRD becomes one of the world's leaders.
The 6 GeV electron synchrotron was accomplished in 1967. During 1970-1991 synchrotron was operated with energies up to 4,5 GeV and in Experimental Physics Division were obtained significant results, including: hadronic properties of photons in π- meson photo-production on nuclei; structures of nucleon resonances in multi-polarization experiments, structure and characteristics of nuclear matter, important properties of X-ray transition radiation and channeling in monocrystals. Thanks to these achievements physicists from Yerevan Physics Institute started from 1985 are successfully participating in the large international collaborations.
Traditional topic of YerPhI is the development of new particle detectors. Wide spark chambers and transition radiation detectors are examples of the experimental techniques developed and implemented in YerPhI. During the last years groups of scientists from Yerevan Physics Institute have actively participated in intermediate and high energy physics experiments abroad (JLAB, DESY, CERN-LHC, MAX-lab, MAMI), exploring the meson and nucleon structures, electromagnetic interactions of the nucleon, quark-hadron duality, short range nucleon-nucleon correlations, quark hadronization in nuclear medium, physics beyond standard model, Higgs boson searches, quark-gluon plasma, fission and fragmentation of nuclei and hypernuclei and many other topics, as well as constructing experimental hardware and develop the software for data acquisition and analysis.
The theoretical department assure major achievements in the following areas: B-meson physics, QCD and Related Phenomenology, Neutrino physics, Quantum Field Theory, String/M-theory, Integrable Models, Statistical physics, Condensed Matter and Quantum Information. These results are internationally recognized and highly cited.
In the mid-1980s in YerPhI was developed the concept of stereoscopic approach in Very High Energy gamma-ray astronomy using multiple Imaging Atmospheric Cherenkov Telescopes (IACT). This concept was materialized in the very successful IACT system (HEGRA). After first success, Armenian physicists successfully participate in operation of the IACT systems on the Canary islands (MAGIC) and in Namibia (H.E.S.S.).
In the course of many years, the Applied Physics Department of YerPhI successfully investigates electron-energy structure of new wide-band laser materials using synchrotron radiation in various spectral regions. The investigations were carried in DESY and will be continued in MaxLab- II (Sweden).
Below are the integral parameters characterizing the efficiency of research conducted by national lab: number of publications and citations. The sizable enlargement of both parameters during last years is apparent. National lab scientists publish appr. 30% of scientific publications of Armenia. Most of publications appear in high impact factor journals; high quality of research in national lab is proved by citations – more than 60% of overall citations to papers published by scientists from Armenia belong to national lab.
Structure.
The YerPhI has seven divisions and Computer Centre.
Experimental physics workshops are also parts of the institute. The main fields of research are:
Directors


Molar volume

In chemistry and related fields, the molar volume, symbol "V"m, or formula_1 of a substance is the occupied volume divided by the amount of substance at a given temperature and pressure. It is equal to the molar mass ("M") divided by the mass density ("ρ"):
It has the SI unit of cubic metres per mole (m3/mol), although it is typically more practical to use the units cubic decimetres per mole (dm3/mol) for gasses, and cubic centimetres per mole (cm3/mol) for liquids and solids.
Definition.
The molar volume of a substance is defined as its molar mass divided by its density:
For an ideal mixture containing "N" components, the molar volume is the weighted sum of the molar volumes of its individual components. For a real mixture the molar volume cannot be calculated without knowing the density:
There are many liquid–liquid mixtures, for instance mixing pure ethanol and pure water, which may experience contraction or expansion upon mixing. This effect is called "excess volume".
Ideal gases.
For ideal gases, the molar volume is given by the ideal gas equation; this is a good approximation for many common gases at standard temperature and pressure.
The ideal gas equation can be rearranged to give an expression for the molar volume of an ideal gas:
Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is based on the gas constant: "R" = , or about .
The molar volume of an ideal gas at 100 kPa (1 bar) is
The molar volume of an ideal gas at 1 atmosphere of pressure is
Crystalline solids.
For crystalline solids, the molar volume can be measured by X-ray crystallography.
The unit cell volume ("V"cell) may be calculated from the unit cell parameters, whose determination is the first step in an X-ray crystallography experiment (the calculation is performed automatically by the structure determination software). This is related to the molar volume by
where "N"A is the Avogadro constant and "Z" is the number of formula units in the unit cell. The result is normally reported as the "crystallographic density".
Molar volume of silicon.
Silicon is routinely made for the electronics industry, and the measurement of the molar volume of silicon, both by X-ray crystallography and by the ratio of molar mass to mass density, has attracted much attention since the pioneering work at NIST by Deslattes "et al." (1974). The interest stems from that accurate measurements of the unit cell volume, atomic weight and mass density of a pure crystalline solid provide a direct determination of the Avogadro constant.
The CODATA recommended value for the molar volume of silicon is , with a relative standard uncertainty of


Lucio Rossi

Lucio Rossi (born 24 September 1955) is an Italian physicist who is working in the field of superconductivity. An author of more than 140 publications in international journals and reviews, he has served as a researcher and professor at the University of Milan. Today, he is working at CERN where he is presently the project leader of the HL-LHC project.
Biography.
Lucio Rossi was born in Podenzano, Italy on 24 September 1955.
In 1980 he obtained his PhD from University of Milan with a thesis on plasma physics.
He was an academic researcher for many years after, interested in applied superconductivity for particle accelerators and in 1992 he became Professor of Experimental Physics in the University of Milan.
During the 1990s, Rossi was involved in many experiments such as the Superconducting Cyclotron (SC) currently in Catania, HERA at DESY in Hamburg and Large Hadron Collider at Cern. His main activities were the design and construction of coils, solenoids, superconductors and prototypes for magnets.
From 2001-2011 he led the Magnet Superconductor and Cryostat Group(MSC) for the LHC project. Since 2011 he has been leader of the High Luminosity for LHC.
Since 1985 Rossi is one of the founders of "Euresis", a Milan-based association for the promotion of scientific culture established in Milan.


Anomalous electric dipole moment

In particle physics, the anomalous electric dipole moment, or the electric dipole moment of a particle in short, is the electric dipole moment of a particle. There is a symmetry, the CP symmetry, which if exact and unbroken will predict an exactly zero electric dipole moment for particles. However, we know at least in the Yukawa sector from neutral kaon oscillations that CP is broken. Experiments have been performed to measure the electric dipole moment of various particles like the electron and the neutron. Many models beyond the standard model with additional CP-violating terms generically predict a nonzero electric dipole moment and are hence sensitive to such new physics. Instanton corrections from a nonzero θ term in quantum chromodynamics predict a nonzero electric dipole moment for the neutron (it is easier to measure the electric dipole moment in a neutral particle) which have not been observed. This is the strong CP problem and is a prediction of chiral perturbation theory.


Gail McConnell

Gail McConnell (born 25 August 1976) is a Scottish physicist who is Professor of Physics and director of the Centre for Biophotonics at the University of Strathclyde. She is interested in optical microscopy and novel imaging techniques, and leads the Mesolens microscope facility where her research investigates linear and non-linear optics.
Early life and education.
McConnell credits her high school physics teacher with her inspiration to study science. She studied optoelectronics and laser physics at the University of Strathclyde, where she was taught by Carol Trager-Cowan. She remained there for her graduate studies, earning a PhD in laser technology under the supervision of in 2002. She was the first member of her family to go to university.
Career and research.
McConnell almost worked in telecommunications, but was convinced by Ferguson to join Strathclyde's new Centre for Biophotonics. She became interested in biomedical research and increasingly aware of the limitations of commercial imaging. Here she worked with Alison Gurney on the development of confocal, multi-photon wide-field microscopes. Gurney encouraged McConnell to apply for fellowships, and she was a Royal Society of Edinburgh and Research Councils UK (RCUK) postdoctoral fellow. She developed the world's first white light supercontinuum laser that could be used for confocal microscopy, as well as laser scanning fluorescence microscopy. She attended the European Molecular Biology Laboratory (EMBL) Practical Course in Advanced Optical Microscopy in Plymouth, which she has continued to support throughout her academic career.
McConnell directs the Centre for Biophotonics and "Mesolens" laboratory at the University of Strathclyde, working on nonlinear and linear optical instrumentation for biomedical imaging. Nonlinear optics allows physicists precise control of excitation parameters, including the chance to tune the duration of laser pules.
In 2009, McConnell began working with William Bradshaw Amos and built a new lens, "Mesolens", that can allow 3D imaging with a depth resolution of a few microns for objects up to 6 mm wide and 3 mm thick. The "Mesolens" is a giant optical microscope objective supported by the Medical Research Council (MRC). It can be used to image large biomedical specimens, including embryos, tumours and areas in brain, as well as scanning large areas of samples in a short amount of time. The lens has 260 megapixal effective camera and a magic ratio of 8:1, which can even resolve individual bacteria. As the photometric volume can sample such a large area with sub-cellular detail, the "Mesolens" may allow for the imaging of rare events. "Mesolens" became a University spin-off, but McConnell decided to stay in academia to explore the physics of biomedical processes. The "Mesolens" generates such large amounts of data that McConnell became interested in computational biology. The "Mesolens" was selected by "Physics World" as one of the top achievements of 2016. She discussed the "Mesolens" on the podcast "Not Exactly Rocket Science".
Alongside the "Mesolens", McConnell has explored how laser sources can be used to open voltage-gated ion channels, such as Calcium-activated potassium channels. She has developed a fast-acquisition version of two-photon excitation microscopy that can be used to image at rates of 100 frames/second. She created polymer hydrogel beads that are responsive to enzymes. She is working with the Medical Research Scotland to create high brightness light-emitting diodes.
In May 2012, she was appointed Professor and Director of the Centre for Biophotonics at the University of Strathclyde. She leads the Strathclyde Theme of Physics and Life Sciences and is part of the Engineering and Physical Sciences Research Council (EPSRC) Centre for Doctoral Training in Optical Medical Imaging.
Awards and honours.
In recognition of her work, McConnell was elected a Fellow of the Institute of Physics (FInstP) in 2010, a Fellow of the Royal Society of Edinburgh (FRSE) in 2019 and a Fellow of the Royal Microscopical Society (FRMS).


Giovanni Cantoni

Giovanni Cantoni (31 December 1818 – 15 July 1897) was an Italian physicist and political figure.
Life.
He taught at the University of Pavia, where Carlo Marangoni was among his students, and headed the Italian metrological service from 1865–1878.
In 1848, he participated in the Five Days of Milan and directed the secretary of defense committee for the provisional government of Lombardy. In 1872, he became a member of the Accademia dei Lincei.


Bernd T. Matthias

Bernd Theodor Matthias (June 8, 1918 – October 27, 1980) was a German-born American physicist credited with discoveries of hundreds of elements and alloys with superconducting properties. He was said to have discovered more elements and compounds with superconducting properties than any other scientist.
Education and career.
Matthias was born in Frankfurt, Germany on June 8, 1918. He received his PhD in physics from the Federal Institute of Technology in Zurich in 1943. He immigrated to the United States in 1947 and went to work for Bell Laboratories.
He taught at the Massachusetts Institute of Technology and the University of Chicago before joining the physics faculty of University of California, San Diego in 1961. He remained at UCSD for the rest of his career, conducting research and mentoring students who became distinguished physicists in their turn. He is best known for his work on solid state physics and the behavior of matter at extremely low temperatures; he also did important work on ferroelectricity. Matthias was also a member of the JASON defense advisory group.
Awards.
In 1965 he was elected to both the National Academy of Sciences and the American Academy of Arts and Sciences.
He received the Oliver E. Buckley Condensed Matter Prize in 1970 and James C. McGroddy Prize for New Materials in 1979.
Recognition.
The University of California, San Diego has an endowed chair in physics named for him; the Bernd T. Matthias Chair in Physics is currently held by M. Brian Maple, who received his PhD under Mathias.
The Bernd T. Matthias Prize for Superconducting Materials was created in 1989 and is awarded annually at the M2S (Materials and Mechanisms of Superconductivity) Conference to recognize innovative contributions to the material aspects of superconductivity. The award was originally sponsored by Bell Labs; since 2000 it has been sponsored by the Texas Center for Superconductivity at the University of Houston, whose founding director, Paul C. W. Chu, was Matthias’ former student.


One-way speed of light

When using the term 'the speed of light' it is sometimes necessary to make the distinction between its one-way speed and its two-way speed. The "one-way" speed of light, from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector. What can however be experimentally measured is the round-trip speed (or "two-way" speed of light) from the source to the detector and back again. Albert Einstein chose a synchronization convention (see Einstein synchronization) that made the one-way speed equal to the two-way speed. The constancy of the one-way speed in any given inertial frame is the basis of his special theory of relativity, although all experimentally verifiable predictions of this theory do not depend on that convention.
Experiments that attempted to directly probe the one-way speed of light independent of synchronization have been proposed, but none has succeeded in doing so.
Those experiments directly establish that synchronization with slow clock-transport is equivalent to Einstein synchronization, which is an important feature of special relativity. Though those experiments don't directly establish the isotropy of the one-way speed of light, because it was shown that slow clock-transport, the laws of motion, and the way inertial reference frames are defined, already involve the assumption of isotropic one-way speeds and thus are conventional as well. In general, it was shown that these experiments are consistent with anisotropic one-way light speed as long as the two-way light speed is isotropic.
The 'speed of light' in this article refers to the speed of all electromagnetic radiation in vacuum.
The two-way speed.
The two-way speed of light is the average speed of light from one point, such as a source, to a mirror and back again. Because the light starts and finishes in the same place only one clock is needed to measure the total time, thus this speed can be experimentally determined independently of any clock synchronization scheme. Any measurement in which the light follows a closed path is considered a two-way speed measurement.
Many tests of special relativity such as the Michelson–Morley experiment and the Kennedy–Thorndike experiment have shown within tight limits that in an inertial frame the two-way speed of light is isotropic and independent of the closed path considered. Isotropy experiments of the Michelson–Morley type do not use an external clock to directly measure the speed of light, but rather compare two internal frequencies or clocks. Therefore, such experiments are sometimes called "clock anisotropy experiments", since every arm of a Michelson interferometer can be seen as a light clock having a specific rate, whose relative orientation dependences can be tested.
Since 1983 the metre has been "defined" as the distance traveled by light in vacuum in second. This means that the speed of light can no longer be experimentally measured in SI units, but the length of a meter can be compared experimentally against some other standard of length.
The one-way speed.
Although the average speed over a two-way path can be measured, the one-way speed in one direction or the other is undefined (and not simply unknown), unless one can define what is "the same time" in two different locations. To measure the time that the light has taken to travel from one place to another it is necessary to know the start and finish times as measured on the same time scale. This requires either two synchronized clocks, one at the start and one at the finish, or some means of sending a signal instantaneously from the start to the finish. No instantaneous means of transmitting information is known. Thus the measured value of the average one-way speed is dependent on the method used to synchronize the start and finish clocks. This is a matter of convention.
The Lorentz transformation is defined such that the one-way speed of light will be measured to be independent of the inertial frame chosen.
Some authors such as Mansouri and Sexl (1977) as well as Will (1992) argued that this problem doesn't affect measurements of the isotropy of the one-way speed of light, for instance, due to direction dependent changes relative to a "preferred" (aether) frame Σ. They based their analysis on a specific interpretation of the RMS test theory in relation to experiments in which light follows a unidirectional path and to slow clock-transport experiments. Will agreed that it is impossible to measure the one-way speed between two clocks using a time-of-flight method without synchronization scheme, though he argued: "...a test of the isotropy of the speed between the same two clocks as the orientation of the propagation path varies relative to Σ should not depend on how they were synchronized...". He added that aether theories can only be made consistent with relativity by introducing ad hoc hypotheses. In more recent papers (2005, 2006) Will referred to those experiments as measuring the ""isotropy of light speed using one-way propagation".
However, others such as Zhang (1995, 1997) and Anderson "et al". (1998) showed this interpretation to be incorrect. For instance, Anderson "et al." pointed out that the conventionality of simultaneity must already be considered in the preferred frame, so all assumptions concerning the isotropy of the one-way speed of light and other velocities in this frame are conventional as well. Therefore, RMS remains a useful test theory to analyze tests of Lorentz invariance and the two-way speed of light, though not of the one-way speed of light. They concluded :"...one cannot hope even to test the isotropy of the speed of light without, in the course of the same experiment, deriving a one-way numerical value at least in principle, which then would contradict the conventionality of synchrony."" Using generalizations of Lorentz transformations with anisotropic one-way speeds, Zhang and Anderson pointed out that all events and experimental results compatible with the Lorentz transformation and the isotropic one-way speed of light must also be compatible with transformations preserving two-way light speed constancy and isotropy, while allowing anisotropic one-way speeds.
Synchronization conventions.
The way in which distant clocks are synchronized can have an effect on all time-related measurements over distance, such as speed or acceleration measurements. In isotropy experiments, simultaneity conventions are often not explicitly stated but are implicitly present in the way coordinates are defined or in the laws of physics employed.
Einstein convention.
This method synchronizes distant clocks in such a way that the one-way speed of light becomes equal to the two-way speed of light. If a signal sent from A at time formula_1 is arriving at B at time formula_2 and coming back to A at time formula_3, then the following convention applies:
The details of this method, and the conditions that assure its consistency are discussed in Einstein synchronization.
Slow clock-transport.
It is easily demonstrated that if two clocks are brought together and synchronized, then one clock is moved rapidly away and back again, the two clocks will no longer be synchronized. This effect is due to time dilation. This was measured in a variety of tests and is related to the twin paradox.
However, if one clock is moved away slowly in frame S and returned the two clocks will be very nearly synchronized when they are back together again. The clocks can remain synchronized to an arbitrary accuracy by moving them sufficiently slowly. If it is taken that, if moved slowly, the clocks remain synchronized at all times, even when separated, this method can be used to synchronize two spatially separated clocks. In the limit as the speed of transport tends to zero, this method is experimentally and theoretically equivalent to the Einstein convention. Though the effect of time dilation on those clocks cannot be neglected anymore when analyzed in another relatively moving frame S'. This explains why the clocks remain synchronized in S, whereas they are not synchronized anymore from the viewpoint of S', establishing relativity of simultaneity in agreement with Einstein synchronization. Therefore, testing the equivalence between these clock synchronization schemes is important for special relativity, and some experiments in which light follows a unidirectional path have proven this equivalence to high precision.
Non-standard synchronizations.
As demonstrated by Hans Reichenbach and Adolf Grünbaum, Einstein synchronization is only a special case of a broader synchronization scheme, which leaves the two-way speed of light invariant, but allows for different one-way speeds. The formula for Einstein synchronization is modified by replacing ½ with ε:
ε can have values between 0 and 1. It was shown that this scheme can be used for observationally equivalent reformulations of the Lorentz transformation, see Generalizations of Lorentz transformations with anisotropic one-way speeds.
As required by the experimentally proven equivalence between Einstein synchronization and slow clock-transport synchronization, which requires knowledge of time dilation of moving clocks, the same non-standard synchronisations must also affect time dilation. It was indeed pointed out that time dilation of moving clocks depends on the convention for the one-way velocities used in its formula. That is, time dilation can be measured by synchronizing two stationary clocks A and B, and then the readings of a moving clock C are compared with them. Changing the convention of synchronization for A and B makes the value for time dilation (like the one-way speed of light) directional dependent. The same conventionality also applies to the influence of time dilation on the Doppler effect. Only when time dilation is measured on closed paths, it is not conventional and can unequivocally be measured like the two-way speed of light. Time dilation on closed paths was measured in the Hafele–Keating experiment and in experiments on the time dilation of moving particles such as Bailey "et al". (1977).
Thus the so-called twin paradox occurs in all transformations preserving the constancy of the two-way speed of light.
Inertial frames and dynamics.
It was argued against the conventionality of the one-way speed of light that this concept is closely related to dynamics, the laws of motion and inertial reference frames. Salmon described some variations of this argument using momentum conservation, from which it follows that two equal bodies at the same place which are equally accelerated in opposite directions, should move with the same one-way velocity. Similarly, Ohanian argued that inertial reference frames are defined so that Newton's laws of motion hold in first approximation. Therefore, since the laws of motion predict isotropic one-way speeds of moving bodies with equal acceleration, and because of the experiments demonstrating the equivalence between Einstein synchronization and slow clock-transport synchronization, it appears to be required and directly measured that the one-way speed of light is isotropic in inertial frames. Otherwise, both the concept of inertial reference frames and the laws of motion must be replaced by much more complicated ones involving anisotropic coordinates.
However, it was shown by others that this is principally not in contradiction with the conventionality of the one-way speed of light. Salmon argued that momentum conservation in its standard form assumes isotropic one-way speed of moving bodies from the outset. So it involves practically the same convention as in the case of isotropic one-way speed of light, thus using this as an argument against light speed conventionality would be circular. And in response to Ohanian, both Macdonald and Martinez argued that even though the laws of physics become more complicated with non-standard synchrony, they still are a consistent way to describe the phenomena. They also argued that it's not necessary to define inertial frames in terms of Newton's laws of motion, because other methods are possible as well. In addition, Iyer and Prabhu distinguished between "isotropic inertial frames" with standard synchrony and "anisotropic inertial frames" with non-standard synchrony.
Experiments which appear to measure the one-way speed of light.
Experiments which claimed to use a one-way light signal.
The Greaves, Rodriguez and Ruiz-Camacho experiment.
In the October 2009 issue of the American Journal of Physics Greaves, Rodriguez and Ruiz-Camacho proposed a new method of measurement of the one-way speed of light. In the June 2013 issue of the American Journal of Physics Hankins, Rackson and Kim repeated the Greaves et al. experiment intending to obtain with greater accuracy the one way speed of light. This experiment assumed that the signal return path to the measuring device has a constant delay, independent of the end point of the light flight path, allowing measurement of the time of flight in a single direction.
J. Finkelstein showed that the Greaves et al. experiment actually measures the round trip (two-way) speed of light.
Experiments in which light follows a unidirectional path.
Many experiments intended to measure the one-way speed of light, or its variation with direction, have been (and occasionally still are) performed in which light follows a unidirectional path. Claims have been made that those experiments have measured the one-way speed of light independently of any clock synchronisation convention, but they have all been shown to actually measure the two-way speed, because they are consistent with generalized Lorentz transformations including synchronizations with different one-way speeds on the basis of isotropic two-way speed of light (see sections the one-way speed and generalized Lorentz transformations).
These experiments also confirm agreement between clock synchronization by slow transport and Einstein synchronization. Even though some authors argued that this is sufficient to demonstrate the isotropy of the one-way speed of light, it has been shown that such experiments cannot, in any meaningful way, measure the (an)isotropy of the one way speed of light unless inertial frames and coordinates are defined from the outset so that space and time coordinates as well as slow clock-transport are described isotropically (see sections inertial frames and dynamics and the one-way speed). Regardless of those different interpretations, the observed agreement between those synchronization schemes is an important prediction of special relativity, because this requires that transported clocks undergo time dilation (which itself is synchronization dependent) when viewed from another frame (see sections Slow clock-transport and Non-standard synchronizations).
The JPL experiment.
This experiment, carried out in 1990 by the NASA Jet Propulsion Laboratory, measured the time of flight of light signals through a fibre optic link between two hydrogen maser clocks. In 1992 the experimental results were analysed by Clifford Will who concluded that the experiment did actually measure the one-way speed of light.
In 1997 the experiment was re-analysed by Zhang who showed that, in fact, only the two-way speed had been measured.
Rømer's measurement.
The first experimental determination of the speed of light was made by Ole Christensen Rømer. It may seem that this experiment measures the time for light to traverse part of the Earth's orbit and thus determines its one-way speed, however, this experiment was carefully re-analysed by Zhang, who showed that the measurement does not measure the speed independently of a clock synchronization scheme but actually used the Jupiter system as a slowly-transported clock to measure the light transit times.
The Australian physicist Karlov also showed that Rømer actually measured the speed of light by implicitly making the assumption of the equality of the speeds of light back and forth.
Experiments that can be done on the one-way speed of light.
Although experiments cannot be done in which the one-way speed of light is measured independently of any clock synchronization scheme, it is possible to carry out experiments that measure a change in the one-way speed of light due, for example, to the motion of the source. Such experiments are the De Sitter double star experiment (1913), conclusively repeated in the X-ray spectrum by K. Brecher in 1977;
or the terrestrial experiment by Alväger, "et al". (1963); they show that, when measured in an inertial frame, the one-way speed of light is independent of the motion of the source within the limits of experimental accuracy. In such experiments the clocks may be synchronized in any convenient way, since it is only a change of speed that is being measured.
Observations of the arrival of radiation from distant astronomical events have shown that the one-way speed of light does not vary with frequency, that is, there is no vacuum dispersion of light. Similarly, differences in the one-way propagation between left- and right-handed photons, leading to vacuum birefringence, were excluded by observation of the simultaneous arrival of distant star light. For current limits on both effects, often analyzed with the Standard-Model Extension, see "Vacuum dispersion" and "Vacuum birefringence".
Experiments on two-way and one-way speeds using the Standard-Model Extension.
While the experiments above were analyzed using generalized Lorentz transformations as in the Robertson–Mansouri–Sexl test theory, many modern tests are based on the Standard-Model Extension (SME). This test theory includes all possible Lorentz violations not only of special relativity, but of the Standard Model and General relativity as well. Regarding the isotropy of the speed of light, both two-way and one-way limits are described using coefficients (3x3 matrices):
A series of experiments have been (and still are) performed since 2002 testing all of those coefficients using, for instance, symmetric and asymmetric optical resonators. No Lorentz violations have been observed as of 2013, providing current upper limits for Lorentz violations: formula_9, formula_10, and formula_11. For details and sources see Modern searches for Lorentz violation#Speed of light.
However, the partially conventional character of those quantities was demonstrated by Kostelecky "et al", pointing out that such variations in the speed of light can be removed by suitable coordinate transformations and field redefinitions. Though this doesn't remove the Lorentz violation "per se", since such a redefinition only transfers the Lorentz violation from the photon sector to the matter sector of SME, thus those experiments remain valid tests of Lorentz invariance violation. There are one-way coefficients of the SME that cannot be redefined into other sectors, since different light rays from the same distance location are directly compared with each other, see the previous section.
Theories in which the one-way speed of light is not equal to the two-way speed.
Theories equivalent to special relativity.
Lorentz ether theory.
In 1904 and 1905, Hendrik Lorentz and Henri Poincaré proposed a theory which explained this result as being due to the effect of motion through the aether on the lengths of physical objects and the speed at which clocks ran. Due to motion through the aether objects would shrink along the direction of motion and clocks would slow down. Thus, in this theory, slowly transported clocks do not, in general, remain synchronized although this effect cannot be observed. The equations describing this theory are known as the Lorentz transformations. In 1905 these transformations became the basic equations of Einstein's special theory of relativity which proposed the same results without reference to an aether.
In the theory, the one-way speed of light is principally only equal to the two-way speed in the aether frame, though not in other frames due to the motion of the observer through the aether. However, the difference between the one-way and two-way speeds of light can never be observed due to the action of the aether on the clocks and lengths. Therefore, the Poincaré-Einstein convention is also employed in this model, making the one-way speed of light isotropic in all frames of reference.
Even though this theory is experimentally indistinguishable from special relativity, Lorentz's theory is no longer used for reasons of philosophical preference and because of the development of general relativity.
Generalizations of Lorentz transformations with anisotropic one-way speeds.
A sychronisation scheme proposed by Reichenbach and Grünbaum, which they called ε-synchronization, was further developed by authors such as Edwards (1963), Winnie (1970), Anderson and Stedman (1977), who reformulated the Lorentz transformation without changing its physical predictions. For instance, Edwards replaced Einstein's postulate that the one-way speed of light is constant when measured in an inertial frame with the postulate:
So the average speed for the round trip remains the experimentally verifiable two-way speed, whereas the one-way speed of light is allowed to take the form in opposite directions:
κ can have values between 0 and 1. In the extreme as κ approaches 1, light might propagate in one direction instantaneously, provided it takes the entire round-trip time to travel in the opposite direction. Following Edwards and Winnie, Anderson "et al." formulated generalized Lorentz transformations for arbitrary boosts of the form:
(with κ and κ' being the synchrony vectors in frames S and S', respectively). This transformation indicates the one-way speed of light is conventional in all frames, leaving the two-way speed invariant. κ=0 means Einstein synchronization which results in the standard Lorentz transformation. As shown by Edwards, Winnie and Mansouri-Sexl, by suitable rearrangement of the synchrony parameters even some sort of "absolute simultaneity" can be achieved, in order to simulate the basic assumption of Lorentz ether theory. That is, in one frame the one-way speed of light is chosen to be isotropic, while all other frames take over the values of this "preferred" frame by "external synchronization".
All predictions derived from such a transformation are experimentally indistinguishable from those of the standard Lorentz transformation; the difference is only that the defined clock time varies from Einstein's according to the distance in a specific direction.
Theories not equivalent to special relativity.
Test theories.
A number of theories have been developed to allow assessment of the degree to which experimental results differ from the predictions of relativity. These are known as test theories and include the Robertson and Mansouri-Sexl (RMS) theories. To date, all experimental results agree with special relativity within the experimental uncertainty.
Another test theory is the Standard-Model Extension (SME). It employs a broad variety of coefficients indicating Lorentz symmetry violations in special relativity, general relativity, and the Standard Model. Some of those parameters indicate anisotropies of the two-way and one-way speed of light. However, it was pointed out that such variations in the speed of light can be removed by suitable redefinitions of the coordinates and fields employed. Though this doesn't remove Lorentz violations "per se", it only shifts their appearance from the photon sector into the matter sector of SME (see above Experiments on two-way and one-way speeds using the Standard-Model Extension.


Feret diameter

The Feret diameter or Feret's diameter is a measure of an object size along a specified direction. In general, it can be defined as the distance between the two parallel planes restricting the object perpendicular to that direction. It is therefore also called the caliper diameter, referring to the measurement of the object size with a caliper. This measure is used in the analysis of particle sizes, for example in microscopy, where it is applied to projections of a three-dimensional (3D) object on a 2D plane. In such cases, the Feret diameter is defined as the distance between two parallel tangential "lines" rather than "planes".
Mathematical properties.
From Cauchy's theorem it follows that for a 2D convex body, the Feret diameter averaged over all directions (〈F〉) is equal to the ratio of the object perimeter (P) and pi, i.e.,〈F〉= P/. There is no such relation between〈F〉and P for a concave object.
Applications.
Feret diameter is used in the analysis of particle size and its distribution, e.g. in a powder or a polycrystalline solid; Alternative measures include Martin diameter, Krumbein diameter and Heywood diameter. The term first became common in scientific literature in the 1970s and can be traced to L.R. Feret (after whom the diameter is named) in the 1930s
It is also used in biology as a method to analyze the size of cells in tissue sections.


Anthony Milner Lane

Anthony Milner Lane (1928–2011) was a leading theoretical nuclear physicist who had a career in the Theoretical Physics Division at the Atomic Energy and Research Establishment (AERE) at Harwell.
He was elected Fellow of the Royal Society in 1975.


Carlos Stroud

Carlos Ray Stroud, Jr. (born July 9, 1942, in Owensboro, KY) is an American physicist and an educator. A pioneer in the field of quantum optics, Stroud has carried out theoretical and experimental studies in most areas of the field from its beginnings in the late 1960s, studying the fundamentals of the quantum mechanics of atoms and light and their interaction. He has authored over 140 peer-reviewed papers and edited seven books. He is a fellow of the American Physical Society and the Optical Society of America, as well as a Distinguished Traveling Lecturer of the Division of Laser Science of the American Physical Society. In this latter position he travels to smaller colleges giving colloquia and public lectures.
Life and career.
Carlos Stroud grew up in Kentucky and graduated from Centre College in 1963, with degrees in mathematics and physics. In 1969 he earned a Ph.D. in physics from Washington University, under the mentorship of E. T. Jaynes, with the thesis titled Quantum and Semiclassical Radiation Theory. In 1969 Stroud joined the faculty of The Institute of Optics at the University of Rochester. Over his 50-year career at the University of Rochester, Professor Stroud taught undergraduate and graduate courses in general and quantum physics and optics, while conducting groundbreaking research in several areas of quantum optics, graduating 30 Ph.D.s. He was named Professor of Optics in 1984 and Professor of Physics and Astronomy in 1991.
In 2004, Stroud collected and edited "A Jewel in the Crown: Essays in Honor of the 75th Anniversary of the Institute of Optics", a compilation of 75 essays on the history of the University of Rochester's Institute of Optics (19 of the essays were authored or co-authored by Stroud himself). In 2019, Stroud and Gina Kern co-edited "A Jewel in the Crown II: Essays in Honor of the 90th Anniversary of the Institute of Optics". For his contributions in gathering and documenting the Institute of Optics' history, on his retirement on July 1, 2019, Stroud was named Professor Emeritus of Optics and Optics Historian.
Professional contributions.
Soon after joining the faculty of the Institute of Optics at the University of Rochester, Stroud collaborated with Michael Hercher, developing the first single-mode tunable dye laser and using it to study its interaction with sodium atoms in an atomic beam. This work produced a series of groundbreaking experiments, including the study of the hyperfine structure of the D-lines, the isolation of a closed two-level resonance, power broadening, and resonance fluorescence in this system. This first observation of the Mollow sidebands in resonance fluorescence was fundamental to understanding of the nature of quantum correlations in a coherently pumped two-level system. It is noteworthy that groups at MIT and the Max Planck Institute in Garching were also racing to be first to observe this spectrum, and did indeed confirm the initial results.
These experimental observations were soon followed by two-laser studies of three-level quantum systems. The first cw study of the Autler–Townes effect, and the first experimental study of the extremely sharp resonance associated with coherent population trapping were made. This observation led to the later development of electromagnetically induced transparency by Harris and others, as well as Stimulated Raman Adiabatic Passage (STIRAP). These pioneering experimental studies were accompanied by theoretical papers providing the underpinning concepts and models, and introducing much of the standard terminology of the fields, including “lambda”, “v”, and “cascade” for describing three-level configurations, “coherent population trapping” as well as introducing, with Cohen-Tannoudji, the dressed-state basis for resonance fluorescence and Autler-Townes studies.
In a series of some 50 papers from the early 1980s well into the 2000s, Stroud’s group studied the production and evolution of spatially localized electron wave packetsmade up of superpositions of Rydberg atomic states. These states are quite classical in their behavior, travelling several orbits around the nucleus as effectively Keplerian systems, but after a few orbits the packets demonstrate their quantum nature by undergoing decays, revivals and fractional revivals. In a fractional revival the initial wave packet splits into a set of smaller wave packets moving in the classical orbit. Parker and Stroud were the first to predict these fractional revivals, which were then observed by Yeazell and Stroud. This whole series of studies showed how a quantum system could be manipulated in a very controlled fashion to alternatively show classical and quantum features during a complex time evolution. A single electron could be made to interfere with itself to exhibit interference fringes, or to move like a classical localized particle. By the application of Stark fields and THz half-cycle pulses, the electrons could even be made to oscillate, while localized along a linear orbit some 1000 Angstroms in length.


Shlomo Sawilowsky

Shlomo S. Sawilowsky was professor of educational statistics and Distinguished Faculty Fellow at Wayne State University in Detroit, Michigan, where he has received teaching, mentoring, and research awards.
Academic career.
Sawilowsky obtained his Ph.D. in 1985 at the University of South Florida. He was inducted into the USF chapter of the Phi Kappa Phi honor society on May 17, 1981, when he received his M.A. In 2008 Sawilowsky served as president of the American Educational Research Association Special Interest Group/Educational Statisticians. He served as an Assistant Dean in the College of Education at WSU. Along with Miodrag Lovric (Serbia) and C. R. Rao (India), he was nominated for the 2013 Nobel Peace Prize for his contributions to the International Encyclopedia of Statistical Science.
Contributions to applied statistics and social/behavioral sciences.
In 2000, the "AMSTAT News", a publication of the American Statistical Association, described Professor Sawilowsky's award of Distinguished Faculty Fellow "in recognition of Sawilowsky's outstanding scholarly achievements in applied statistics, psychometrics, and experimental design in education and psychology."
Applied statistics.
He is the author of a statistics textbook that presents statistical methods via Monte Carlo simulation methods, editor of a volume on real data analysis published by the American Educational Research Association SIG/Educational Statisticians, and author of over a hundred articles in applied statistics and social sciences journals. Sawilowsky has also authored 24 entries in statistics encyclopedias.
His presentation titled "The Rank Transform," with co-author R. Clifford Blair, was awarded the 1985 Florida Educational Research Association & 1986 American Educational Research Association State/Regions Distinguished Paper Award. Many of his publications are related to rank-based nonparametric statistics. For example, an examination of the robustness and comparative power properties of the rank transform statistic was called a "major Monte Carlo study". Hettmansperger and McKean stated that Sawilowsky provided "an excellent review of nonparametric approaches to testing for interaction" (p. 254-255).
Sawilowsky's Monte Carlo work has been cited as an exemplar for designing simulation studies. His work has been cited on a variety of statistical issues, such as
Psychometrics.
In psychological testing, Sawilowsky is a co-author of two self-determination assessment batteries; an instrument designed to assess locus of control, self-esteem, and self-concept among at-risk adolescents; an instrument "which measures future orientation, knowledge of the realities of child rearing, personal intentions, and sexual self-efficacy;" and a college well-being instrument. Sawilowsky was the initial proponent in favor of psychometric theory (reliability refers to the test) over datametric theory (reliability refers to the data), a controversy with implications for test theory, role of tests in expert testimony, test validity, etc. The debate was discussed in "Educational and Psychological Measurement" and elsewhere. Although the issue has not been resolved, the current non-aligned opinion "lean[s] toward the Sawilowsky position." In classical test theory, he developed the "Sawilowsky I" test, a statistical test used to help demonstrate evidence of construct validity in the multitrait-multimethod matrix.
Experimental design.
Sawilowsky's Monte Carlo work on comparing randomized vs quasi-experimental design has been described as "one of the strongest examples" demonstrating limitations of quasi-experimental design, and "provides possibly one of the strongest cases for the superiority of randomized designs."
Mentorship.
In 1998, the "AMSTAT News" reported Sawilowsky's Awards for Excellence in Teaching, and Graduate Mentorship, and noted "Professor Sawilowsky's exceptional record as an academician is reflected in the excellence with which he mentors graduate students." He has mentored 109 doctoral dissertations as major professor according to the Mathematics Genealogy Project.
ProQuest indicates he has chaired dissertations in many other fields, such as kinesiology, nursing education, and teacher education; and co-chaired a dissertation on process drama. He also served as 2nd advisor on many doctoral dissertations, and numerous more as a committee member.
Editorship.
Sawilowsky is the founder and editor of the "Journal of Modern Applied Statistical Methods." It was created to provide an outlet for research using Monte Carlo and other resampling methods, nonparametric and other robust methods, permutation and other exact or approximately exact methods, and statistical algorithms.
Publications.
Books
Selected Articles
Rabbinical studies and contributions to the Judaica literature.
After graduating from the Rabbinical College of America in 1979, Sawilowsky was the emissary of the Grand Rabbi of Lubavitch, Rabbi Menachem Mendel Schneerson, to Pinellas County, Florida. He also obtained a rabbinical degree from Yeshivas Pirchei Shoshanim (Jerusalem, Israel) in 2004, after having studied with the first group of students ever to receive strictly Orthodox Rabbinical ordination curricula on the laws of the Jewish Sabbath delivered via e-mail.
Sawilowsky is the author of a textbook written in dialogue format for preparing food and other matters related to the kitchen for the Sabbath. It is based on the Talmud, Code of Jewish Law (Shulchan Aruch), and Ashkenaz, Sephardi, and Chabad customs. He has published articles on Bible commentary and related topics in the annual journal of Pirchei Shoshanim.


Entanglement witness

In quantum information theory, an entanglement witness is a functional which distinguishes a specific entangled state from separable ones. Entanglement witnesses can be linear or nonlinear functionals of the density matrix. If linear, then they can also be viewed as observables for which the expectation value of the entangled state is strictly outside the range of possible expectation values of any separable state.
Details.
Let a composite quantum system have state space formula_1. A mixed state ρ is then a trace-class positive operator on the state space which has trace 1. We can view the family of states as a subset of the real Banach space generated by the Hermitian trace-class operators, with the trace norm. A mixed state ρ is separable if it can be approximated, in the trace norm, by states of the form
where formula_3's and formula_4's are pure states on the subsystems "A" and "B" respectively. So the family of separable states is the closed convex hull of pure product states. We will make use of the following variant of Hahn–Banach theorem:
Theorem Let formula_5 and formula_6 be disjoint convex closed sets in a real Banach space and one of them is compact, then there exists a bounded functional "f" separating the two sets.
This is a generalization of the fact that, in real Euclidean space, given a convex set and a point outside, there always exists an affine subspace separating the two. The affine subspace manifests itself as the functional "f". In the present context, the family of separable states is a convex set in the space of trace class operators. If ρ is an entangled state (thus lying outside the convex set), then by theorem above, there is a functional "f" separating ρ from the separable states. It is this functional "f", or its identification as an operator, that we call an entanglement witness. There is more than one hyperplane separating a closed convex set from a point lying outside of it, so for an entangled state there is more than one entanglement witness. Recall the fact that the dual space of the Banach space of trace-class operators is isomorphic to the set of bounded operators. Therefore, we can identify "f" with a Hermitian operator "A". Therefore, modulo a few details, we have shown the existence of an entanglement witness given an entangled state:
Theorem For every entangled state ρ, there exists a Hermitian operator A such that
formula_7, and formula_8 for all separable states σ.
When both formula_9 and formula_10 have finite dimension, there is no difference between trace-class and Hilbert–Schmidt operators. So in that case "A" can be given by Riesz representation theorem. As an immediate corollary, we have:
Theorem A mixed state σ is separable if and only if
for any bounded operator A satisfying formula_12, for all product pure state formula_13.
If a state is separable, clearly the desired implication from the theorem must hold. On the other hand, given an entangled state, one of its entanglement witnesses will violate the given condition.
Thus if a bounded functional "f" of the trace-class Banach space and "f" is positive on the product pure states, then "f", or its identification as a Hermitian operator, is an entanglement witness. Such a "f" indicates the entanglement of some state.
Using the isomorphism between entanglement witnesses and non-completely positive maps, it was shown (by the Horodeckis) that
Theorem A mixed state formula_14 is separable if for every positive map Λ from bounded operators on formula_10 to bounded operators on formula_9, the operator formula_17 is positive, where formula_18 is the identity map on formula_19, the bounded operators on formula_9.


Soft Magnetic Materials Conference

The Soft Magnetic Materials Conference, commonly referred to as SMM, is an international conference devoted to all kinds of soft magnetic materials with the emphasis on industrial and applications aspects.
Format and purpose.
The SMM is held for three days, every two years, often at the beginning of September in a European country. Each time the SMM has a different logo.
In SMM18 (organised by Wolfson Centre for Magnetics there were 260 participants from over 30 countries. There were 306 scientific papers presented, out of which around 200 are peer reviewed and will be published in Journal of Magnetism and Magnetic Materials, Elsevier at the beginning of 2008.
In the past the SMM proceedings have also been published in IEEE Transactions on Magnetics
 or other peer reviewed journals.
The SMM is the largest international conference devoted to soft magnetic materials. It has active participation of the academic world as well as of industry, with a high scientific level of contributed and invited communications.
The main aim of the SMM is to bring together engineers and scientists from universities, research institutions and industry who are active in research, development and industrial applications of the materials. The programme of the conference includes invited lectures by academic and industrial experts, oral presentations and poster sessions for regular contributions.
Scope.
Typical topics of the SMM are:
Organising committees.
The conference series has an International Organising Committee, chaired by J.M. Barandiaran, of Bilbao, Spain. The previous chairs were Anthony J. Moses, of Cardiff, UK, who stepped down in 2007, and John E. Thompson who was the founder chair.
For each SMM there is a Local Organising Committee (academic and research members of staff of the local university), which is responsible for local arrangements, venue, technical programme, conference dinner, etc.


Sylvia Fedoruk

Sylvia Olga Fedoruk [Fe-doruk], (Ukrainian: Федорук), (May 5, 1927 – September 26, 2012) was a Canadian physicist, medical physicist, curler and the 17th Lieutenant Governor of Saskatchewan.
Life.
Born in Canora, Saskatchewan, the daughter of Ukrainian immigrants, Annie Romaniuk and Theodore Fedoruk. Fedoruk attended a one room schoolhouse in Wroxton north east of the city of Yorkton. Her father was her teacher.
During World War II, the family relocated to Ontario where her parents took war factory work. In 1946, she completed her studies at Walkerville Collegiate in Windsor Ontario, at the top of her class and was awarded the Ernest J. Creed Memorial Medal and an entrance scholarship to attend University. But the family chose to return to Saskatchewan where Sylvia entered the University of Saskatchewan at Saskatoon in the fall of 1946.
She received a Bachelor of Arts degree in physics, at the University of Saskatchewan, in 1949 and was awarded the Governor General's Gold Medal. Fedoruk completed her M.A. in physics in 1951.
Fedoruk was recruited by Dr. Harold E. Johns to be the radiation physicist at Saskatoon Cancer Clinic. She became the chief medical physicist at the Saskatoon Cancer Clinic and director of physics services at the Saskatchewan Cancer Clinic. She was a professor of oncology and associate member in physics at the University of Saskatchewan. She was involved in the development of the world's first cobalt-60 unit and one of the first nuclear medicine scanning machines. The cobalt-60 beam therapy unit, or the "cobalt bomb" as it was known, was the first of its kind to successfully use targeted radiation to treat cancer in a patient. The machine's collimated beam of radiation could be adjusted to the size of the tumor to irradiate the growth. Fedoruk's masters work on depth-dose measurements for radiation treatment were essential in the success of the beam therapy unit.
She was the first woman member of the Atomic Energy Control Board of Canada.
From 1986 to 1989 she was chancellor of the University of Saskatchewan. She was the first woman to fill this position at the University of Saskatchewan.
She is a past president (1971 to 1972) of the Canadian Ladies Curling Association. In 1986, she was inducted into the Canadian Curling Hall of Fame, as a builder, and was awarded the Saskatchewan Order of Merit. In 1961, she played in the very first Diamond 'D' Championships for team Saskatchewan as the third for Joyce McKee. Saskatchewan won the tournament. 1986 was inducted into the Canadian Curling Hall of Fame.
In 1987, she was made an Officer of the Order of Canada.
From 1988 to 1994, she was Lieutenant Governor of Saskatchewan.
In the 1990s, the City of Saskatoon named a new road, Fedoruk Drive in her honour. The roadway runs from Central Avenue to McOrmond Drive, north of the communities of Silverspring and Evergreen and south of the community of Aspen Ridge and the Northeast Swale. Fedoruk Drive serves as a minor arterial roadway in the northeast sector of the city.
On October 3, 2012 the name of the Canadian Centre for Nuclear Innovation (CCNI) was changed to the Sylvia Fedoruk Canadian Centre for Nuclear Innovation in honor of the pioneering work she did in the treatment of cancer using cobalt-60 radiation therapy in the 1950s.
In 2009, she was inducted into the Canadian Medical Hall of Fame.