title:
"Ideally" unstable current sheets and the triggering of fast magnetic
  reconnection

abstract:
  Magnetic reconnection is thought to be the dynamical mechanism underlying
many explosive phenomena observed both in space and in the laboratory, though
the question of how fast magnetic reconnection is triggered in such high
Lundquist ($S$) number plasmas has remained elusive. It has been well
established that reconnection can develop over timescales faster than those
predicted traditionally once kinetic scales are reached. It has also been shown
that, within the framework of resistive Magnetohydrodynamics (MHD), fast
reconnection is achieved for thin enough sheets via the onset of the so-called
plasmoid instability. The latter was discovered in studies specifically devoted
to the Sweet-Parker current sheet, either as an initial condition or an
apparent transient state developing in nonlinear studies. On the other hand, a
fast tearing instability can grow on an ideal, i.e., $S$-independent, timescale
(dubbed "ideal" tearing) within current sheets whose aspect ratio scales with
the macroscopic Lundquist number as $L/a\sim S^{1/3}$ -- much smaller than the
Sweet-Parker one -- suggesting a new way to approach to the initiation of fast
reconnection in collapsing current configurations. Here we present an overview
of what we have called "ideal" tearing in resistive MHD, and discuss how the
same reasoning can be extended to other plasma models commonly used that
include electron inertia and kinetic effects. We then discuss a scenario for
the onset of "ideal" fast reconnection via collapsing current sheets and
describe a quantitative model for the interpretation of the nonlinear evolution
of "ideally" unstable sheets in two dimensions.


title: Many-anyon trial states

abstract:
  The problem of bounding the (abelian) many-anyon ground-state energy from
above, with a dependence on the statistics parameter which matches that of
currently available lower bounds, is reduced to studying the correlation
functions of Moore-Read (Pfaffian) and Read-Rezayi type clustering states.

categories: quant-ph cond-mat.quant-gas cond-mat.str-el math-ph math.MP


title: Swarm equilibria in domains with boundaries

abstract:
  We study equilibria in domains with boundaries for a first-order aggregation
model that includes social interactions and exogenous forces. Such equilibrium
solutions can be connected or disconnected, the latter consisting in a delta
concentration on the boundary and a free swarm component in the interior of the
domain. Equilibria are stationary points of an energy functional, and stable
configurations are local minimizers of this functional. We find a one-parameter
family of disconnected equilibrium configurations which are not energy
minimizers; the only stable equilibria are the connected states. Nevertheless,
we demonstrate that in certain cases the dynamical evolution, along the
gradient flow of the energy functional, tends to overwhelmingly favour the
formation of (unstable) disconnected equilibria.


title:
Holistic Small Cell Traffic Balancing across Licensed and Unlicensed
  Bands

abstract:
  Due to the dramatic growth in mobile data traffic on one hand and the
scarcity of the licensed spectrum on the other hand, mobile operators are
considering the use of unlicensed bands (especially those in 5 GHz) as
complementary spectrum for providing higher system capacity and better user
experience. This approach is currently being standardized by 3GPP under the
name of LTE Licensed-Assisted Access (LTE-LAA). In this paper, we take a
holistic approach for LTE-LAA small cell traffic balancing by jointly
optimizing the use of the licensed and unlicensed bands. We pose this traffic
balancing as an optimization problem that seeks proportional fair coexistence
of WiFi, small cell and macro cell users by adapting the transmission
probability of the LTE-LAA small cell in the licensed and unlicensed bands. The
motivation for this formulation is for the LTE-LAA small cell to switch between
or aggregate licensed and unlicensed bands depending on the
interference/traffic level and the number of active users in each band. We
derive a closed form solution for this optimization problem and additionally
propose a transmission mechanism for the operation of the LTE-LAA small cell on
both bands. Through numerical and simulation results, we show that our proposed
traffic balancing scheme, besides enabling better LTE-WiFi coexistence and
efficient utilization of the radio resources relative to the existing traffic
balancing scheme, also provides a better tradeoff between maximizing the total
network throughput and achieving fairness among all network flows compared to
alternative approaches.


title:
Testing cosmological models with large-scale power modulation using
  microwave background polarization observations

abstract:
  We examine the degree to which observations of large-scale cosmic microwave
background (CMB) polarization can shed light on the puzzling large-scale power
modulation in maps of CMB anisotropy. We consider a phenomenological model in
which the observed anomaly is caused by modulation of large-scale primordial
curvature perturbations, and calculate Fisher information and error forecasts
for future polarization data, constrained by the existing CMB anisotropy data.
Because a significant fraction of the available information is contained in
correlations with the anomalous temperature data, it is essential to account
for these constraints. We also present a systematic approach to finding a set
of normal modes that maximize the available information, generalizing the
well-known Karhunen-Loeve transformation to take account of the constraints
from the temperature data. A polarization map covering at least $\sim 60\%$ of
the sky should be able to provide a $3\sigma$ detection of modulation at the
level favored by the temperature data. A significant fraction of the
information in such a data set is contained in the single mode that optimally
encapsulates the signal due to temperature-polarization correlation.


title:
Mesoscopic chaos mediated by Drude electron-hole plasma in silicon
  optomechanical oscillators

abstract:
  Chaos has revolutionized the field of nonlinear science and stimulated
foundational studies from neural networks, extreme event statistics, to physics
of electron transport. Recent studies in cavity optomechanics provide a new
platform to uncover quintessential architectures of chaos generation and the
underlying physics. Here we report the generation of dynamical chaos in
silicon-based monolithic optomechanical oscillators, enabled by the strong and
coupled nonlinearities of two-photon-absorption induced Drude electron-hole
plasma. Deterministic chaotic oscillation is achieved, and statistical and
entropic characterization quantifies the chaos complexity at 60 fJ intracavity
energies. The correlation dimension D2 is determined at 1.67 for the chaotic
attractor, along with maximal Lyapunov exponent rate about 2.94 the fundamental
optomechanical oscillation for fast adjacent trajectory divergence. Nonlinear
dynamical maps demonstrate the subharmonics, bifurcations, and stable regimes,
along with distinct transitional routes into chaos. This provides a
CMOS-compatible and scalable architecture for understanding complex dynamics on
the mesoscopic scale.


title: Reflection matrices with $U_q[osp^{(2)}(2|2m)]$ symmetry

abstract:
  We propose a classification of the reflection $K$-matrices (solutions of the
boundary Yang-Baxter equation) for the
$U_{q}[\mathrm{osp}^{\left(2\right)}\left(2|2m\right)]=U_{q}[C^{\left(2\right)}\left(m+1\right)]$
vertex-model. We have found four families of solutions, namely, the complete
solutions, in which no elements of the reflection $K$-matrix is null, the
block-diagonal solutions, the $X$-shape solutions and the diagonal solutions.
We highlight that these diagonal $K$-matrices also hold for the
$U_{q}[\mathrm{osp}^{\left(2\right)}\left(2n+2|2m\right)]=U_{q}[D^{\left(2\right)}\left(n+1,m\right)]$
vertex-model.

categories: nlin.SI cond-mat.stat-mech hep-th math-ph math.MP


title:
Dynamical tuning between nearly perfect reflection, absorption, and
  transmission of light via graphene/dielectric structures

abstract:
  Exerting well-defined control over the reflection $(R)$, absorption $(A)$,
and transmission $(T)$ of electromagnetic waves is a key objective in quantum
optics. To this end, one often utilizes hybrid structures comprised of elements
with different optical properties in order to achieve features such as high $R$
or high $A$ for incident light. A desirable goal would be the possibility to
tune between all three regimes of nearly perfect reflection, absorption, and
transmission within the same device, thus swapping between the cases $R\to 1$,
$A\to1$, and $T\to1$ dynamically. We here show that a dielectric interfaced
with a graphene layer on each side allows for precisely this: by tuning only
the Fermi level of graphene, all three regimes can be reached in the THz regime
and below. Moreover, we show that the inclusion of cylindrical defects in the
system offers a different type of control of the scattering of electromagnetic
waves by means of the graphene layers.


title: Entanglement structure of non-equilibrium steady states

abstract:
  We study the problem of calculating transport properties of interacting
quantum systems, specifically electrical and thermal conductivities, by
computing the non-equilibrium steady state (NESS) of the system biased by
contacts. Our approach is based on the structure of entanglement in the NESS.
With reasonable physical assumptions, we show that a NESS close to local
equilibrium is lightly entangled and can be represented via a computationally
efficient tensor network. We further argue that the NESS may be found by
dynamically evolving the system within a manifold of appropriate low
entanglement states. A physically realistic law of dynamical evolution is
Markovian open system dynamics, or the Lindblad equation. We explore this
approach in a well-studied free fermion model where comparisons with the
literature are possible. We study both electrical and thermal currents with and
without disorder, and compute entropic quantities such as mutual information
and conditional mutual information. We conclude with a discussion of the
prospects of this approach for the challenging problem of transport in strongly
interacting systems, especially those with disorder.


title:
Investigating the Relation between CO (3-2) and Far Infrared
  Luminosities for Nearby Merging Galaxies Using ASTE

abstract:
  We present the new single dish CO (3-2) emission data obtained toward 19
early stage and 7 late stage nearby merging galaxies using the Atacama
Submillimeter Telescope Experiment (ASTE). Combining with the single dish and
interferometric data of galaxies observed in previous studies, we investigate
the relation between the CO (3-2) luminosity (L'CO(3-2)) and the far Infrared
luminosity (LFIR) in a sample of 29 early stage and 31 late stage merging
galaxies, and 28 nearby isolated spiral galaxies. We find that normal isolated
spiral galaxies and merging galaxies have different slopes (alpha) in the log
L'CO(3-2) - log LFIR plane (alpha ~ 0.79 for spirals and ~ 1.12 for mergers).
The large slope (alpha > 1) for merging galaxies can be interpreted as an
evidence for increasing Star Formation Efficiency (SFE=LFIR/L'CO(3-2)) as a
function of LFIR. Comparing our results with sub-kpc scale local star formation
and global star-burst activity in the high-z Universe, we find deviations from
the linear relationship in the log L'CO(3-2) - log LFIR plane for the late
stage mergers and high-z star forming galaxies. Finally, we find that the
average SFE gradually increases from isolated galaxies, merging galaxies, and
to high-z submillimeter galaxies / quasi-stellar objects (SMGs/QSOs). By
comparing our findings with the results from numerical simulations, we suggest;
(1) inefficient star-bursts triggered by disk-wide dense clumps occur in the
early stage of interaction and (2) efficient star-bursts triggered by central
concentration of gas occur in the final stage. A systematic high spatial
resolution survey of diffuse and dense gas tracers is a key to confirm this
scenario.


title:
X-Ray Emitting Active Galactic Nuclei from z = 0.6-1.3 in the
  Intermediate and High-Density Environments of the ORELSE Survey

abstract:
  We studied AGN activity in twelve LSSs in the ORELSE survey, at 0.65<z<1.28,
using a combination of Chandra observations, optical and NIR imaging and
spectroscopy. We located a total of 61 AGNs across our sample that were
successfully matched to optical counterparts in the LSSs. Seeking to study AGN
triggering mechanisms, we examined the spatial distribution of the AGNs and
their average spectral properties. We found that AGN populations across our
sample had less time since the last starburst than the overall galaxy
populations. We did not find any relation between AGN activity and location
within the LSSs, suggesting triggering mechanisms which depend on global
environment are at most sub-dominant. To focus on differences between our AGNs,
we grouped them into four sub-samples based on the spectral properties of their
parents LSSs. We found one of the sub-samples, SG0023 & SC1604, stood out from
the others: AGNs in this sample were disproportionately luminous, their average
time since the last starburst event was the smallest, despite the fact that
this was not true of the overall galaxy population in those LSSs, and both the
AGNs and the overall galaxy population had the largest fraction of close
kinematic pairs, which indicates a higher rate of galaxy mergers and
interactions. These results suggest that major mergers are driving AGN activity
in SG0023 & SC1604, while other processes are likely triggering less luminous
AGNs in the rest of our sample. Additionally, minor mergers are unlikely to
play a significant role, since the same conditions that lead to more major
mergers should should also lead to more minor mergers, which is not observed in
SG0023 & SC1604.


title: Bosonization and Mirror Symmetry

abstract:
  We study bosonization in 2+1 dimensions using mirror symmetry, a duality that
relates pairs of supersymmetric theories. Upon breaking supersymmetry in a
controlled way, we dynamically obtain the bosonization duality that equates the
theory of a free Dirac fermion to QED3 with a single scalar boson. This duality
may be used to demonstrate the bosonization duality relating an
$O(2)$-symmetric Wilson-Fisher fixed point to QED3 with a single Dirac fermion,
Peskin-Dasgupta-Halperin duality, and the recently conjectured duality relating
the theory of a free Dirac fermion to fermionic QED3 with a single flavor.
Chern-Simons and BF couplings for both dynamical and background gauge fields
play a central role in our approach. In the course of our study, we describe a
chiral mirror pair that may be viewed as the minimal supersymmetric
generalization of the two bosonization dualities.


title:
The effects of individual metal contents on isochrones for C, N, O, Na,
  Mg, Al, Si, and Fe

abstract:
  The individual characteristics of C, N, O, Na, Mg, Al, Si, and Fe on
isochrones have been investigated in this study. Stellar models have been
constructed for various mixtures in which the content of each element is
changed up to the extreme value reported in recent studies, and the changes in
isochrone shape have been analyzed for the various mixtures. To express the
abundance variation of different elements with a single parameter, we have
focused on the relative changes in the total number of metal ions. A review of
the shape changes revealed that Na, Mg, and Al work the same way in stellar
models, as the well-known fact that C, N, and O have the same reactions in the
stellar interior. In addition, it was found that in high-metallicity conditions
the influence of Si and Fe on the red giant branch becomes smaller than that of
Na, Mg, and Al closer to the tip. Furthermore, the influence of Fe on the main
sequence is larger than that of Na, Mg, Al, and even Si.


title:
Differentiating G-inflation from String Gas Cosmology using the
  Effective Field Theory Approach

abstract:
  A characteristic signature of String Gas Cosmology is primordial power
spectra for scalar and tensor modes which are almost scale-invariant but with a
red tilt for scalar modes but a blue tilt for tensor modes. This feature,
however, can also be realized in the so-called G-inflation model, in which
Horndeski operators are introduced which leads to a blue tensor tilt by softly
breaking the Null Energy Condition. In this article we search for potential
observational differences between these two cosmologies by performing detailed
perturbation analyses based on the Effective Field Theory approach. Our results
show that, although both two models produce blue tilted tensor perturbations,
they behave differently in three aspects. Firstly, String Gas Cosmology
predicts a specific consistency relation between the index of the scalar modes
ns and that of tensor ones nt, which is hard to be reproduced by G-inflation.
Secondly, String Gas Cosmology typically predicts non-Gaussianities which are
highly suppressed on observable scales, while G-inflation gives rise to
observationally large non-Gaussianities because the kinetic terms in the action
become important during inflation. However, after finely tuning the model
parameters of G-inflation it is possible to obtain a blue tensor spectrum and
negligible non-Gaussianities with a degeneracy between the two models. This
degeneracy can be broken by a third observable, namely the scale dependence of
the nonlinearity parameter, which vanishes for G-inflation but has a blue tilt
in the case of String Gas Cosmology. Therefore, we conclude that String Gas
Cosmology is in principle observationally distinguishable from the single field
inflationary cosmology, even allowing for modifications such as G-inflation.


title: A resolved map of the infrared excess in a Lyman Break Galaxy at z=3

abstract:
  We have observed the dust continuum of ten z=3.1 Lyman Break Galaxies with
the Atacama Large Millimeter/Submillimeter Array at ~450 mas resolution in Band
7. We detect and resolve the 870um emission in one of the targets with an
integrated flux density of S(870)=(192+/-57) uJy, and measure a stacked 3-sigma
signal of S(870)=(67+/-23) uJy for the remaining nine. The total infrared
luminosities estimated from full spectral energy distribution fits are
L(8-1000um)=(8.4+/-2.3)x10^10 Lsun for the detection and
L(8-1000um)=(2.9+/-0.9)x10^10 Lsun for the stack. With HST ACS I-band imaging
we map the rest-frame UV emission on the same scale as the dust, effectively
resolving the 'infrared excess' (IRX=L_FIR/L_UV) in a normal galaxy at z=3.
Integrated over the galaxy we measure IRX=0.56+/-0.15, and the galaxy-averaged
UV slope is beta=-1.25+/-0.03. This puts the galaxy a factor of ~10 below the
IRX-beta relation for local starburst nuclei of Meurer et al. (1999). However,
IRX varies by more than a factor of 3 across the galaxy, and we conclude that
the complex relative morphology of the dust relative to UV emission is largely
responsible for the scatter in the IRX-beta relation at high-z. A naive
application of a Meurer-like dust correction based on the UV slope would
dramatically over-estimate the total star formation rate, and our results
support growing evidence that when integrated over the galaxy, the typical
conditions in high-z star-forming galaxies are not analogous to those in the
local starburst nuclei used to establish the Meurer relation.


title:
BBQ-Networks: Efficient Exploration in Deep Reinforcement Learning for
  Task-Oriented Dialogue Systems

abstract:
  We present a new algorithm that significantly improves the efficiency of
exploration for deep Q-learning agents in dialogue systems. Our agents explore
via Thompson sampling, drawing Monte Carlo samples from a Bayes-by-Backprop
neural network. Our algorithm learns much faster than common exploration
strategies such as $\epsilon$-greedy, Boltzmann, bootstrapping, and
intrinsic-reward-based ones. Additionally, we show that spiking the replay
buffer with experiences from just a few successful episodes can make Q-learning
feasible when it might otherwise fail.


title: Faint Dwarf Galaxies in Hickson Compact Group 90

abstract:
  We report the discovery of a very diverse set of five low-surface brightness
(LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in
deep U- and I-band images obtained with VLT/VIMOS. These are the first LSB
dwarf galaxy candidates found in a compact group of galaxies. We measure
spheroid half-light radii in the range $0.7\!\lesssim\! r_{\rm eff}/{\rm kpc}\!
\lesssim\! 1.5$ with luminosities of $-11.65\!\lesssim\! M_U\! \lesssim\!
-9.42$ and $-12.79\!\lesssim\! M_I\! \lesssim\! -10.58$ mag, corresponding to a
color range of $(U\!-\!I)_0\!\simeq\!1.1\!-\!2.2$ mag and surface brightness
levels of $\mu_U\!\simeq\!28.1\,{\rm mag/arcsec^2}$ and
$\mu_I\!\simeq\!27.4\,{\rm mag/arcsec^2}$. Their colours and luminosities are
consistent with a diverse set of stellar population properties. Assuming solar
and 0.02 Z$_\odot$ metallicities we obtain stellar masses in the range
$M_*|_{Z_\odot} \simeq 10^{5.7-6.3} M_{\odot}$ and
$M_*|_{0.02\,Z_\odot}\!\simeq\!10^{6.3-8}\,M_{\odot}$. Three dwarfs are older
than 1 Gyr, while the other two significantly bluer dwarfs are younger than
$\sim 2$ Gyr at any mass/metallicity combination. Altogether, the new LSB dwarf
galaxy candidates share properties with dwarf galaxies found throughout the
Local Volume and in nearby galaxy clusters such as Fornax. We find a pair of
candidates with $\sim\!2$ kpc projected separation, which may represent one of
the closest dwarf galaxy pairs found. We also find a nucleated dwarf candidate,
with a nucleus size of $r_{\rm eff}\!\simeq\!46\!-\!63$ pc and magnitude
M$_{U,0}=-7.42$ mag and $(U\!-\!I)_0\!=\!1.51$ mag, which is consistent with a
nuclear stellar disc with a stellar mass in the range $10^{4.9-6.5}\,M_\odot$.


title: A generalized Theory of Diffusion based on Kinetic Theory

abstract:
  We propose to use spin hydrodynamics, a two-fluid model of spin propagation,
as a generalization of the diffusion equation. We show that in the dense limit
spin hydrodynamics reduces to Fick's law and the diffusion equation. In the
opposite limit spin hydrodynamics is equivalent to a collisionless Boltzmann
treatment of spin propagation. Spin hydrodynamics avoids unphysical effects
that arise when the diffusion equation is used to describe to a strongly
interacting gas with a dilute corona. We apply spin hydrodynamics to the
problem of spin diffusion in a trapped atomic gas. We find that the observed
spin relaxation rate in the high temperature limit [Sommer et al., Nature 472,
201 (2011)] is consistent with the diffusion constant predicted by kinetic
theory.


title: PRIMUS: One- and Two-Halo Galactic Conformity at $0.2 < z < 1$

abstract:
  We test for galactic conformity at $0.2<z<1.0$ to a projected distance of 5
Mpc using spectroscopic redshifts from the PRism MUlti-object Survey (PRIMUS).
Our sample consists of $\sim60,000$ galaxies in five separate fields covering a
total of $\sim5.5$ square degrees, which allows us to account for cosmic
variance. We identify star-forming and quiescent "isolated primary" (i.e.,
central) galaxies using isolation criteria and cuts in specific star formation
rate. We match the redshift and stellar mass distributions of these samples, to
control for correlations between quiescent fraction and redshift and stellar
mass. We detect a significant $(>3\sigma)$ one-halo conformity signal, or an
excess of star-forming neighbors around star-forming central galaxies, of
$\sim5$% on scales of 0-1 Mpc and a $2.5\sigma$ two-halo signal of $\sim1$% on
scales of 1-3 Mpc. These signals are weaker than those detected in SDSS and are
consistent with galactic conformity being the result of large-scale tidal
fields and reflecting assembly bias. We also measure the star-forming fraction
of central galaxies at fixed stellar mass as a function of large-scale
environment and find that central galaxies are more likely to be quenched in
overdense environments, independent of stellar mass. However, we find that
environment does not affect the star formation efficiency of central galaxies,
as long as they are forming stars. We test for redshift and stellar mass
dependence of the conformity signal within our sample and show that large
volumes and multiple fields are required at intermediate redshift to adequately
account for cosmic variance.


title:
Exploding Satellites -- The Tidal Debris of the Ultra-Faint Dwarf Galaxy
  Hercules

abstract:
  The ultra-faint satellite galaxy Hercules has a strongly elongated and
irregular morphology with detections of tidal features up to 1.3 deg (3 kpc)
from its center. This suggests that Hercules may be dissolving under the Milky
Way's gravitational influence, and hence could be a tidal stream in formation
rather than a bound, dark-matter dominated satellite. Using Bayesian inference
in combination with N-body simulations, we show that Hercules has to be on a
very eccentric orbit (epsilon~0.95) within the Milky Way in this scenario. On
such an orbit, Hercules "explodes" as a consequence of the last tidal shock at
pericenter 0.5 Gyr ago. It is currently decelerating towards apocenter of its
orbit with a velocity of V=157 km/s -- of which 99% is directed radially
outwards. Due to differential orbital precession caused by the non-spherical
nature of the Galactic potential, its debris fans out nearly perpendicular to
its orbit. This explains why Hercules has an elongated shape without showing a
distance gradient along its main body: it is in fact a stream that is
significantly broader than it is long. In other words, it is moving
perpendicular to its apparent major axis. In this scenario, there is a spike in
the radial velocity profile created by the dominant debris component that
formed through the last pericenter passage. This is similar to kinematic
substructure that is observed in the real Hercules. Modeling a satellite on
such a highly eccentric orbit is strongly dependent on the form of the Galactic
potential. We therefore propose that detailed kinematic investigation of
Hercules and other exploding satellite candidates can yield strong constraints
on the potential of the Milky Way.


title: Testing galaxy formation models with galaxy stellar mass functions

abstract:
  We compare predictions of a number of empirical models and numerical
simulations of galaxy formation to the conditional stellar mass functions
(CSMF)of galaxies in groups of different masses obtained recently by Lan et al.
to test how well different models accommodate the data. The observational data
clearly prefer a model in which star formation in low-mass halos changes
behavior at a characteristic redshift $z_c\sim 2$. There is also tentative
evidence that this characteristic redshift depends on environment, becoming
$z_c\sim 4$ in regions that eventually evolve into rich clusters of galaxies.
The constrained model is used to understand how galaxies form and evolve in
dark matter halos, and to make predictions for other statistical properties of
the galaxy population, such as the stellar mass functions of galaxies at high
$z$, the star formation and stellar mass assembly histories in dark matter
halos. A comparison of our model predictions with those of other empirical
models shows that different models can make vastly different predictions, even
though all of them are tuned to match the observed stellar mass functions of
galaxies.


title:
From immunity to sudden death: Effects of strong disorder in strongly
  correlated superconductors

abstract:
  We investigate the effect of strong disorder on a system with strong
electronic repulsion. In absence of disorder, the system has a d-wave
superconducting ground-state with strong non-BCS features due to its proximity
to a Mott insulator. We find that, while strong correlations make
superconductivity in this system immune to weak disorder, superconductivity is
destroyed efficiently when disorder strength is comparable to the effective
bandwidth. The suppression of charge motion in regions of strong potential
fluctuation leads to formation of Mott insulating patches, which anchor a
larger non-superconducting region around them. The system thus breaks into
islands of Mott insulating and superconducting regions, with Anderson
insulating regions occurring along the boundary of these regions. Thus,
electronic correlation and disorder, when both are strong, aid each other in
destroying superconductivity, in contrast to their competition at weak
disorder. Our results shed light on why Zinc impurities are efficient in
destroying superconductivity in cuprates, even though it is robust to weaker
impurities.


title: The Dynamics of Supertranslations and Superrotations in 2+1 Dimensions

abstract:
  Supertranslations, and at least in 2+1 dimensions superrotations, are
asymptotic symmetries of the metric in asymptotically flat spacetimes. They are
not, however, symmetries of the boundary term of the Einstein-Hilbert action,
which therefore induces an action for the Goldstone-like fields that
parametrize these symmetries. I show that in 2+1 dimensions, this action is
closely related to a chiral Liouville action, as well as the "Schwarzian"
action that appears in two-dimensional near-AdS physics.


title: Quantum Codes from High-Dimensional Manifolds

abstract:
  We construct toric codes on various high-dimensional manifolds. Assuming a
conjecture in geometry we find families of quantum CSS stabilizer codes on $N$
qubits with logarithmic weight stabilizers and distance $N^{1-\epsilon}$ for
any $\epsilon>0$. The conjecture is that there is a constant $C>0$ such that
for any $n$-dimensional torus ${\mathbb T}^n={\mathbb R}^n/\Lambda$, where
$\Lambda$ is a lattice, the least volume unoriented $n/2$-dimensional surface
(using the Euclidean metric) representing nontrivial homology has volume at
least $C^n$ times the volume of the least volume $n/2$-dimensional hyperplane
representing nontrivial homology; in fact, it would suffice to have this result
for $\Lambda$ an integral lattice with the surface restricted to faces of a
cubulation by unit hypercubes. The main technical result is an estimate of
Rankin invariants\cite{rankin} for certain random lattices, showing that in a
certain sense they are optimal. Additionally, we construct codes with
square-root distance, logarithmic weight stabilizers, and inverse
polylogarithmic soundness factor (considered as quantum locally testable
codes\cite{qltc}). We also provide an short, alternative proof that the
shortest vector in the exterior power of a lattice may be
non-split\cite{coulangeon}.


title: Matrix Quantum Mechanics from Qubits

abstract:
  We introduce a transverse field Ising model with order N^2 spins interacting
via a nonlocal quartic interaction. The model has an O(N,Z), hyperoctahedral,
symmetry. We show that the large N partition function admits a saddle point in
which the symmetry is enhanced to O(N). We further demonstrate that this
`matrix saddle' correctly computes large N observables at weak and strong
coupling. The matrix saddle undergoes a continuous quantum phase transition at
intermediate couplings. At the transition the matrix eigenvalue distribution
becomes disconnected. The critical excitations are described by large N matrix
quantum mechanics. At the critical point, the low energy excitations are waves
propagating in an emergent 1+1 dimensional spacetime.


title: Circularly ordered dynamical systems

abstract:
  We study topological properties of circularly ordered dynamical systems and
prove that every such system is representable on a Rosenthal Banach space,
hence, is also tame. We derive some consequences for topological groups. We
show that several Sturmian like symbolic $\mathbb{Z}^k$-systems are circularly
ordered. Using some old results we characterize circularly ordered minimal
cascades.


title:
Quenched Magnon excitations by oxygen sublattice reconstruction in
  (SrCuO$_2$)$_n$/(SrTiO$_3$)$_2$ superlattices

abstract:
  The recently discovered structural reconstruction in the cuprate superlattice
(SrCuO$_2$)$_n$/(SrTiO$_3$)$_2$ has been investigated across the critical value
of $n=5$ using resonant inelastic x-ray scattering (RIXS). We find that at the
critical value of $n$, the cuprate layer remains largely in the bulk-like
two-dimensional structure with a minority of Cu plaquettes being reconstructed.
The partial reconstruction leads to quenching of the magnons starting at the
$\Gamma$-point due to the minority plaquettes acting as scattering points.
Although comparable in relative abundance, the doped charge impurities in
electron-doped cuprate superconductors do not show this quenching of magnetic
excitations.


title:
Probing the influence of dielectric environment on excitons in monolayer
  WSe2: Insight from high magnetic fields

abstract:
  Excitons in atomically-thin semiconductors necessarily lie close to a
surface, and therefore their properties are expected to be strongly influenced
by the surrounding dielectric environment. However, systematic studies
exploring this role are challenging, in part because the most readily
accessible exciton parameter -- the exciton's optical transition energy -- is
largely \textit{un}affected by the surrounding medium. Here we show that the
role of the dielectric environment is revealed through its systematic influence
on the \textit{size} of the exciton, which can be directly measured via the
diamagnetic shift of the exciton transition in high magnetic fields. Using
exfoliated WSe$_2$ monolayers affixed to single-mode optical fibers, we tune
the surrounding dielectric environment by encapsulating the flakes with
different materials, and perform polarized low-temperature magneto-absorption
studies to 65~T. The systematic increase of the exciton's size with dielectric
screening, and concurrent reduction in binding energy (also inferred from these
measurements), is quantitatively compared with leading theoretical models.
These results demonstrate how exciton properties can be tuned in future 2D
optoelectronic devices.


title: Tolerant Compressed Sensing With Partially Coherent Sensing Matrices

abstract:
  Most of compressed sensing (CS) theory to date is focused on incoherent
sensing, that is, columns from the sensing matrix are highly uncorrelated.
However, sensing systems with naturally occurring correlations arise in many
applications, such as signal detection, motion detection and radar. Moreover,
in these applications it is often not necessary to know the support of the
signal exactly, but instead small errors in the support and signal are
tolerable.
  Despite the abundance of work utilizing incoherent sensing matrices, for this
type of tolerant recovery we suggest that coherence is actually beneficial. We
promote the use of coherent sampling when tolerant support recovery is
acceptable, and demonstrate its advantages empirically. In addition, we provide
a first step towards theoretical analysis by considering a specific
reconstruction method for selected signal classes.


title: Birth of a giant $(k_1,k_2)$-core in the random digraph

abstract:
  The $(k_1,k_2)$-core of a digraph is the largest sub-digraph with minimum
in-degree and minimum out-degree at least $k_1$ and $k_2$ respectively. For
$\max\{k_1, k_2\} \geq 2$, we establish existence of the threshold edge-density
$c^*=c^*(k_1,k_2)$, such that the random digraph $D(n,m)$, on the vertex set
$[n]$ with $m$ edges, asymptotically almost surely has a giant $(k_1,k_2)$-core
if $m/n> c^*$, and has no $(k_1,k_2)$-core if $m/n<c^*$. Specifically, denoting
$\text{P}(\text{Poisson}(z)\ge k)$ by $p_k(z)$, we prove that
$c^*=\min\limits_{z_1,z_2}\max\left\{\tfrac{z_1}{p_{k_1}(z_1)p_{k_2-1}(z_2)};
\tfrac{z_2}{p_{k_1-1}(z_1)p_{k_2}(z_2)}\right\}$.


title: Helical Floquet Channels in 1D Lattices

abstract:
  We show how dispersionless channels exhibiting perfect spin-momentum locking
can arise in a 1D lattice model. While such spectra are forbidden by fermion
doubling in static 1D systems, here we demonstrate their appearance in the
stroboscopic dynamics of a periodically driven system. Remarkably, this
phenomenon does not rely on any adiabatic assumptions, in contrast to the well
known Thouless pump and related models of adiabatic spin pumps. The proposed
setup is shown to be experimentally feasible with state of the art techniques
used to control ultracold alkaline earth atoms in optical lattices.


title: Secret Sharing With Trusted Third Parties Using Piggy Bank Protocol

abstract:
  This paper presents a new scheme to distribute secret shares using two
trusted third parties to increase security and eliminate the dependency on
single trusted third party. This protocol for communication between a device
and two trusted third parties uses the piggy bank cryptographic paradigm. We
also present a protocol to give law enforcing agencies access to sensitive
information present on a cell phone or a device using secret sharing scheme.
The ideas for classical systems may also be applied to quantum schemes.


title:
A unified approach to autocorrelation of Frank, Chu, and Milewski
  sequences

abstract:
  We construct a family of perfect polyphase sequences that has the Frank
sequences, Chu sequences, and Milewski sequences as special cases. This is not
the most general construction of this type, but it has a particularly simple
form. We also include some remarks about the acyclic autocorrelations of our
sequences.


title:
A roadmap for searching cosmic rays correlated with the extraterrestrial
  neutrinos seen at IceCube

abstract:
  We have built regions in a Sky map where it should be expected the arrival of
120 EeV ultrahigh energy cosmic rays (UHECR) directionally correlated with the
latest astrophysical neutrino tracks observed at IceCube, which are taken as
point sources. In order to calculate these arrival directions we have
considered contributions to the cosmic rays deflections originated by the
galactic and the extragalactic magnetic field, and a UHECR composition
compatible with the current expectations. We have used the Jansson-Farrar JF12
model for the Galactic magnetic field and an extragalactic magnetic field
strength of 1nG and coherence length of 1Mpc. We observe that the regions
outside of the Galactic plane are more strongly correlated with the neutrino
tracks than those adjacent to or in it, with the former regions being good
candidates to search for excesses, or anisotropies, in the UHECR flux.
Additionally, we have focused, as an example, on the region of 150 EeV UHECR
arrival directions correlated with the IceCube event 37 located at
$(l,b)=(-137.1^\circ,65.8^\circ)$ in the Northern Hemisphere, far away from the
Galactic plane, obtaining an angular size $\sim 5^\circ$, being $\sim 3^\circ$
for 200 EeV, and $\sim 8^\circ$ for 120 EeV. The results presented in this
paper represent a useful UHECR excess search Sky map guide.


title: In-Place Sparse Suffix Sorting

abstract:
  Suffix arrays encode the lexicographical order of all suffixes of a text and
are often combined with the Longest Common Prefix array (LCP) to simulate
navigational queries on the suffix tree in reduced space. In space-critical
applications such as sparse and compressed text indexing, only information
regarding the lexicographical order of a size-$b$ subset of all $n$ text
suffixes is often needed. Such information can be stored space-efficiently (in
$b$ words) in the sparse suffix array (SSA). The SSA and its relative sparse
LCP array (SLCP) can be used as a space-efficient substitute of the sparse
suffix tree. Very recently, Gawrychowski and Kociumaka [SODA 2017] showed that
the sparse suffix tree (and therefore SSA and SLCP) can be built in
asymptotically optimal $O(b)$ space with a Monte Carlo algorithm running in
$O(n)$ time. The main reason for using the SSA and SLCP arrays in place of the
sparse suffix tree is, however, their reduced space of $b$ words each. This
leads naturally to the quest for in-place algorithms building these arrays.
Franceschini and Muthukrishnan [ICALP 2007] showed that the full suffix array
can be built in-place and in optimal running time. On the other hand, finding
sub-quadratic in-place algorithms for building the SSA and SLCP for
\emph{general} subsets of suffixes has been an elusive task for decades. In
this paper, we give the first solution to this problem. We provide the first
in-place algorithm building the full LCP array in $O(n\log n)$ expected time
and the first Monte Carlo in-place algorithms building the SSA and SLCP in $O(n
+ b\log^2 n)$ expected time. We moreover describe the first in-place solution
for the suffix selection problem: to compute the $i$-th smallest text suffix.


title: On entanglement spreading in chaotic systems

abstract:
  We discuss the time dependence of subsystem entropies in interacting quantum
systems. As a model for the time dependence, we suggest that the entropy is as
large as possible given two constraints: one follows from the existence of an
emergent light cone, and the other is a conjecture associated to the
"entanglement velocity" $v_E$. We compare this model to new holographic and
spin chain computations, and to an operator growth picture. Finally, we
introduce a second way of computing the emergent light cone speed in
holographic theories that provides a boundary dynamics explanation for a
special case of entanglement wedge subregion duality in AdS/CFT.


title: Complex Correntropy: Probabilistic Interpretation and Optimization

abstract:
  Recent studies have demonstrated that correntropy is an efficient tool for
analyzing higher-order statistical moments in nonGaussian noise environments.
Although correntropy has been used with complex data, no theoretical study was
pursued to elucidate its properties, nor how to best use it for optimization.
This paper presents a probabilistic interpretation for correntropy using
complex-valued data called complex correntropy. A recursive solution for the
maximum complex correntropy criterion (MCCC) is introduced based on a fixed
point solution. This technique is applied to a simple system identification
case study, and the results demonstrate prominent advantages when compared to
the complex recursive least squares (RLS) algorithm. By using such
probabilistic interpretation, correntropy can be applied to solve several
problems involving complex data in a more straightforward way. Keywords:
complex-valued data correntropy, maximum complex correntropy criterion,
fixed-point algorithm.


title: The Irreducible Subgroups of Exceptional Algebraic Groups

abstract:
  This paper is a contribution to the study of the subgroup structure of
exceptional algebraic groups over algebraically closed fields of arbitrary
characteristic. Following Serre, a closed subgroup of a semisimple algebraic
group $G$ is called irreducible if it lies in no proper parabolic subgroup of
$G$. In this paper we complete the classification of irreducible connected
subgroups of exceptional algebraic groups, providing an explicit set of
representatives for the conjugacy classes of such subgroups. Many consequences
of this classification are also given. These include results concerning the
representations of such subgroups on various $G$-modules: for example, the
conjugacy classes of irreducible connected subgroups are determined by their
composition factors on the adjoint module of $G$, with one exception.
  A result of Liebeck and Testerman shows that each irreducible connected
subgroup $X$ of $G$ has only finitely many overgroups and hence the overgroups
of $X$ form a lattice. We provide tables that give representatives of each
conjugacy class of overgroups within this lattice structure. We use this to
prove results concerning the subgroup structure of $G$: for example, when the
characteristic is 2, there exists a maximal connected subgroup of $G$
containing a conjugate of every irreducible subgroup $A_1$ of $G$.


title:
Scene Labeling Through Knowledge-Based Rules Employing Constrained
  Integer Linear Programing

abstract:
  Scene labeling task is to segment the image into meaningful regions and
categorize them into classes of objects which comprised the image. Commonly
used methods typically find the local features for each segment and label them
using classifiers. Afterward, labeling is smoothed in order to make sure that
neighboring regions receive similar labels. However, they ignore expressive and
non-local dependencies among regions due to expensive training and inference.
In this paper, we propose to use high-level knowledge regarding rules in the
inference to incorporate dependencies among regions in the image to improve
scores of classification. Towards this aim, we extract these rules from data
and transform them into constraints for Integer Programming to optimize the
structured problem of assigning labels to super-pixels (consequently pixels) of
an image. In addition, we propose to use soft-constraints in some scenarios,
allowing violating the constraint by imposing a penalty, to make the model more
flexible. We assessed our approach on three datasets and obtained promising
results.


title: Evolutionary Approaches to Optimization Problems in Chimera Topologies

abstract:
  Chimera graphs define the topology of one of the first commercially available
quantum computers. A variety of optimization problems have been mapped to this
topology to evaluate the behavior of quantum enhanced optimization heuristics
in relation to other optimizers, being able to efficiently solve problems
classically to use them as benchmarks for quantum machines. In this paper we
investigate for the first time the use of Evolutionary Algorithms (EAs) on
Ising spin glass instances defined on the Chimera topology. Three genetic
algorithms (GAs) and three estimation of distribution algorithms (EDAs) are
evaluated over $1000$ hard instances of the Ising spin glass constructed from
Sidon sets. We focus on determining whether the information about the topology
of the graph can be used to improve the results of EAs and on identifying the
characteristics of the Ising instances that influence the success rate of GAs
and EDAs.


title:
Overcoming experimental limitations in a non-linear two-qubit gate
  through postselection

abstract:
  We introduce a modular-value two-qubit gate and explore its advantages in
experimentally-limited situations. The gate is defined such that the final
state of a target qubit is fully controlled by a pre- and post-selection
procedure in a control qubit given an (imperfect or technically limited)
intermediate conditional qubit-qubit interaction. As an example of the gate and
its benefit, we make the connection to a postselected cross phase modulation
scenario when a undesired absorption is present. Probabilistic amplification of
a small cross phase while mitigating relative absorption is possible, and a
complementary behaviour between phase and amplitude emerges.


title:
Focal overlap gating in velocity map imaging to achieve high
  signal-to-noise ratio in photo-ion pump-probe experiments

abstract:
  We demonstrate a new technique in velocity map imaging (VMI) that allows
spatial gating of the laser focal overlap region in time resolved pump-probe
experiments. This significantly enhances signal-to-noise ratio by eliminating
background signal arising outside the region of spatial overlap of pump and
probe beams. This enhancement is achieved by tilting the laser beams with
respect to the surface of the VMI electrodes which creates a gradient in flight
time for particles born at different points along the beam. By suitably pulsing
our microchannel plate detector, we can select particles born only where the
laser beams overlap. This spatial gating in velocity map imaging can benefit
nearly all photoion pump-probe VMI experiments especially when
extreme-ultraviolet (XUV) light or X-rays are involved which produce large
background signals on their own.


title:
Examination of strangeness instabilities and effects of strange meson
  couplings in dense strange hadronic matter and compact stars

abstract:
  Background : The emergence of hyperon degrees of freedom in neutron star
matter has been associated to first order phase transitions in some
phenomenological models, but conclusions on the possible physical existence of
an instability in the strangeness sector are strongly model dependent. Purpose
: The purpose of the present study is to assess whether strangeness
instabilities are related to specific values of the largely unconstrained
hyperon interactions, and to study the effect of the strange meson couplings on
phenomenological properties of neutron stars and supernova matter, once these
latter are fixed to fulfill the constraints imposed by hypernuclear data.
Method : We consider a phenomenological RMF model sufficiently simple to allow
a complete exploration of the parameter space. Results : We show that no
instability at supersaturation density exists for the RMF model, as long as the
parameter space is constrained by basic physical requirements. This is at
variance with a non-relativistic functional, with a functional behavior fitted
through ab-initio calculations. Once the study is extended to include the full
octet, we show that the parameter space allows reasonable radii for canonical
neutron stars as well as massive stars above two-solar mass, together with an
important strangeness content of the order of 30\%, slightly decreasing with
increasing entropy, even in the absence of a strangeness driven phase
transition. Conclusions : We conclude that the hyperon content of neutron stars
and supernova matter cannot be established with present constraints, and is
essentially governed by the unconstrained coupling to the strange isoscalar
meson.


title: Optimal Management of Naturally Regenerating Uneven-aged Forests

abstract:
  A shift from even-aged forest management to uneven-aged management practices
leads to a problem rather different from the existing straightforward practice
that follows a rotation cycle of artificial regeneration, thinning of inferior
trees and a clearcut. A lack of realistic models and methods suggesting how to
manage uneven-aged stands in a way that is economically viable and ecologically
sustainable creates difficulties in adopting this new management practice. To
tackle this problem, we make a two-fold contribution in this paper. The first
contribution is the proposal of an algorithm that is able to handle a realistic
uneven-aged stand management model that is otherwise computationally tedious
and intractable. The model considered in this paper is an empirically estimated
size-structured ecological model for uneven-aged spruce forests. The second
contribution is on the sensitivity analysis of the forest model with respect to
a number of important parameters. The analysis provides us an insight into the
behavior of the uneven-aged forest model.


title:
Symplectically replacing plumbings with Euler characteristic 2
  4-manifolds

abstract:
  We introduce new symplectic cut-and-paste operations that generalize the
rational blowdown. In particular, we will define $k$-replaceable plumbings to
be those that, heuristically, can be symplectically replaced by Euler
characteristic $k$ 4-manifolds. We will then classify 2-replaceable linear
plumbings, construct 2-replaceable plumbing trees, and use one such tree to
construct a symplectic exotic $\mathbb{C}P^2\#6\overline{\mathbb{C}P^2}$.


title: The Dirac composite fermion of the fractional quantum Hall effect

abstract:
  We review the recently proposed Dirac composite fermion theory of the
half-filled Landau level. This paper is based on a talk given at the Nambu
Symposium at University of Chicago, March 11-13, 2016.


title: Intervening Mg II absorption systems from the SDSS DR12 quasar spectra

abstract:
  We present the catalogue of the Mg II absorption systems detected at a high
significance level using an automated search algorithm in the spectra of
quasars from the twelfth data release of the Sloan Digital Sky Survey. A total
of 266,433 background quasars were searched for the presence of absorption
systems in their spectra. The continuum modelling for the quasar spectra was
performed using a mean filter. A pseudo-continuum derived using a median filter
was used to trace the emission lines. The absorption system catalogue contains
39,694 Mg II systems detected at a 6.0, 3.0$\sigma$ level respectively for the
two lines of the doublet. The catalogue was constrained to an absorption line
redshift of 0.35 $\le$ z$_{2796}$ $\le$ 2.3. The rest-frame equivalent width of
the $\lambda$2796 line ranges between 0.2 $\le$ W$_r$ $\le$ 6.2 $\AA$. Using
Gaussian-noise only simulations we estimate a false positive rate of 7.7 per
cent in the catalogue. We measured the number density $\partial
N^{2796}/\partial z$ of Mg II absorbers and find evidence for steeper evolution
of the systems with W$_r \ge$ 1.2 $\AA$ at low redshifts (z$_{2796}$ $\le$
1.0), consistent with other earlier studies. A suite of null tests over the
redshift range 0.5 $\le$ z$_{2796}$ $\le$ 1.5 was used to study the presence of
systematics and selection effects like the dependence of the number density
evolution of the absorption systems on the properties of the background quasar
spectra. The null tests do not indicate the presence of any selection effects
in the absorption catalogue if the quasars with spectral signal-to-noise level
less than 5.0 are removed. The resultant catalogue contains 36,981 absorption
systems. The Mg II absorption catalogue is publicly available and can be
downloaded from the link http://srini.ph.unimelb.edu.au/mgii.php


title:
Passivation-sensitive exciton finestructure produces excess Stokes
  shifts in colloidal quantum dots

abstract:
  The excitonic finestructure of colloidal quantum dots (CQDs) is comprised of
a manifold of transitions, of which only the lowest are populated and
contribute to photoluminescence. This leads to a Stokes shift in emission
relative to absorption. Here we show experimentally that the Stokes shift in Pb
and Cd-based chalcogenide CQDs is correlated with the degree of surface
passivation, and develop a model that explains how coupling to the surface
affects the core electronic states. Dark and bright transitions can reorder and
split, increasing the Stokes shift even without the formation of deep traps.
Our findings resolve the highly-debated topic of excess Stokes shifts in PbS
nanocrystals as due to parity-forbidden transitions instead of traps. We
predict that the Stokes shift in PbS can be eliminated via core stoichiometry
control, a critical step towards enhancing the open circuit voltage in quantum
dot solar cells.


title: The formulation of the Navier-Stokes equations on Riemannian manifolds

abstract:
  We consider the generalization of the Navier-Stokes equations from $\mathbb
R^n$ to the Riemannian manifolds. There are inequivalent formulations of the
Navier-Stokes equations on manifolds due to the different possibilities for the
Laplacian operator acting on vector fields on a Riemannian manifold. We present
several distinct arguments that indicate that the form of the equations
proposed by Ebin and Marsden in 1970 should be adopted as the correct
generalization of the Navier-Stokes to the Riemannian manifolds.


title:
The Miniature X-ray Solar Spectrometer (MinXSS) CubeSats: spectrometer
  characterization techniques, spectrometer capabilities, and solar science
  objectives

abstract:
  The Miniature X-ray Solar Spectrometer (MinXSS) are twin 3U CubeSats. The
first of the twin CubeSats (MinXSS-1) launched in December 2015 to the
International Space Station for deployment in mid-2016. Both MinXSS CubeSats
utilize a commercial off the shelf (COTS) X-ray spectrometer from Amptek to
measure the solar irradiance from 0.5 to 30 keV with a nominal 0.15 keV FWHM
spectral resolution at 5.9 keV, and a LASP-developed X-ray broadband photometer
with similar spectral sensitivity. MinXSS design and development has involved
over 40 graduate students supervised by professors and professionals at the
University of Colorado at Boulder. The majority of previous solar soft X-ray
measurements have been either at high spectral resolution with a narrow
bandpass or spectrally integrating (broadband) photometers. MinXSS will conduct
unique soft X-ray measurements with moderate spectral resolution over a
relatively large energy range to study solar active region evolution, solar
flares, and the effects of solar soft X-ray emission on Earth's ionosphere.
This paper focuses on the X-ray spectrometer instrument characterization
techniques involving radioactive X-ray sources and the National Institute for
Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility
(SURF). Spectrometer spectral response, spectral resolution, response linearity
are discussed as well as future solar science objectives.

categories: astro-ph.IM astro-ph.HE astro-ph.SR physics.space-ph


title: Spinning $\sigma$-model solitons in $2+1$ Anti-de Sitter space

abstract:
  We obtain numerical solutions for rotating topological solitons of the
nonlinear $\sigma$-model in three-dimensional Anti-de Sitter space. Two types
of solutions, $i)$ and $ii)$, are found. The $\sigma$-model fields are
everywhere well defined for both types of solutions, but they differ in their
space-time domains. Any time slice of the space-time for the type $i)$ solution
has a causal singularity, despite the fact that all scalars constructed the
curvature tensor are bounded functions. No evidence of a horizon is seen for
any of the solutions, and therefore the type $i)$ solutions have naked
singularities.
  On the other hand, the space-time domain, along with the fields, for the type
$ii)$ solutions are singularity free. Multiple families of solutions exhibiting
bifurcation phenomena are found for this case.


title:
An Investigation of Randomized Controlled Trial (RCT) Method as a
  Customer Baseline Load (CBL) Calculation for Residential Customers

abstract:
  FERC Order 745 allows demand response owners to sell their load reduction in
the wholesale market. However, in order to be able to sell the load reduction,
some implementation challenges must be addressed, one of which is to establish
Customer Baseline Load (CBL) calculation methods with acceptable error
performance, which has proven to be very challenging so far. In this paper, the
error and financial performance of Randomized Controlled Trial (RCT) method,
applied to both granular and aggregated forms of the consumption load, are
investigated for a hypothetical demand response program offered to a real
dataset of residential customers .


title:
FIPSER: Performance Study of a Readout Concept With Few Digitization
  Levels for Fast Signals

abstract:
  We discuss the performance of a readout system, Fixed Pulse Shape Efficient
Readout (FIPSER), to digitize signals from detectors with a fixed pulse shape.
In this study we are mainly interested in the readout of fast photon detectors
like photomultipliers or Silicon photomultipliers. But the concept can be
equally applied to the digitization of other detector signals. FIPSER is based
on the flash analog to digital converter (FADC) concept, but has the potential
to lower costs and power consumption by using an order of magnitude fewer
discrete voltage levels. Performance is bolstered by combining the discretized
signal with the knowledge of the underlying pulse shape. Simulated FIPSER data
was reconstructed with two independent methods. One using a maximum likelihood
method and the other using a modified chisquared test. Both methods show that
utilizing 12 discrete voltage levels with a sampling rate of 4 samples per full
width half maximum (FWHM) of the pulse achieves an amplitude resolution that is
better than the Poisson limit for photon-counting experiments. The time
resolution achieved in this configuration ranges between 0.02 - 0.16 FWHM and
depends on the pulse amplitude. In a situation where the waveform is composed
of two consecutive pulses the pulses can be separated if they are at least 0.05
- 0.30 FWHM apart with an amplitude resolution that is better than 20%.


title: Improving randomness characterization through Bayesian model selection

abstract:
  Nowadays random number generation plays an essential role in technology with
important applications in areas ranging from cryptography, which lies at the
core of current communication protocols, to Monte Carlo methods, and other
probabilistic algorithms. In this context, a crucial scientific endeavour is to
develop effective methods that allow the characterization of random number
generators. However, commonly employed methods either lack formality (e.g. the
NIST test suite), or are inapplicable in principle (e.g. the characterization
derived from the Algorithmic Theory of Information (ATI)). In this letter we
present a novel method based on Bayesian model selection, which is both
rigorous and effective, for characterizing randomness in a bit sequence. We
derive analytic expressions for a model's likelihood which is then used to
compute its posterior probability distribution. Our method proves to be more
rigorous than NIST's suite and the Borel-Normality criterion and its
implementation is straightforward. We have applied our method to an
experimental device based on the process of spontaneous parametric
downconversion, implemented in our laboratory, to confirm that it behaves as a
genuine quantum random number generator (QRNG). As our approach relies on
Bayesian inference, which entails model generalizability, our scheme transcends
individual sequence analysis, leading to a characterization of the source of
the random sequences itself.


title:
Zero-field splitting of the Kondo resonance and quantum criticality in
  triple quantum dots

abstract:
  We consider a triple-quantum-dot (TQD) system composed by an interacting
quantum dot connected to two effectively non-interacting dots, which in turn
are both connected in parallel to metallic leads. As we show, this system can
be mapped onto a single-impurity Anderson model with a non-trivial density of
states. The TQD's transport properties are investigated under a continuous
tuning of the non-interacting dots' energy-levels, employing the Numerical
Renormalization Group technique. Interference between single and many-particle
resonances splits the Kondo peak, fulfilling a generalized Friedel sum rule. In
addition, a particular configuration in which one of the non-interacting dots
is held out of resonance with the leads allows to access a pseudogap regime
where a Kosterlitz-Thouless type quantum-phase-transition (QPT) occur,
separating the Kondo and non-Kondo behavior. Within this same configuration,
the TQD exhibits traces of the Fano-Kondo effect, which is in turn, strongly
affected by the QPT. Signatures of all these phenomena are neatly displayed by
the calculated linear conductance.


title:
On the Performance of Cell-Free Massive MIMO with Short-Term Power
  Constraints

abstract:
  In this paper we consider a time-division duplex cell-free massive
multiple-input multiple-output (MIMO) system where many distributed access
points (APs) simultaneously serve many users. A normalized conjugate
beamforming scheme, which satisfies short-term average power constraints at the
APs, is proposed and analyzed taking into account the effect of imperfect
channel information. We derive an approximate closed-form expression for the
per-user achievable downlink rate of this scheme. We also provide, analytically
and numerically, a performance comparison between the normalized conjugate
beamforming and the conventional conjugate beamforming scheme in [1] (which
satisfies long-term average power constraints). Normalized conjugate
beamforming scheme reduces the beamforming uncertainty gain, which comes from
the users' lack of the channel state information knowledge, and hence, it
improves the achievable downlink rate compared to the conventional conjugate
beamforming scheme.


title: Goodness-of-fit test in a multivariate errors-in-variables model $AX=B$

abstract:
  We consider a multivariable functional errors-in-variables model $AX\approx
B$, where the data matrices $A$ and $B$ are observed with errors, and a matrix
parameter $X$ is to be estimated. A goodness-of-fit test is constructed based
on the total least squares estimator. The proposed test is asymptotically
chi-squared under null hypothesis. The power of the test under local
alternatives is discussed.


title:
Signatures of Young Planets in the Continuum Emission From Protostellar
  Disks

abstract:
  Many protostellar disks show central cavities, rings, or spiral arms likely
caused by low-mass stellar or planetary companions, yet few such features are
conclusively tied to bodies embedded in the disks. We note that even small
features on the disk's surface cast shadows, because the starlight grazes the
surface. We therefore focus on accurately computing the disk's thickness, which
depends on its temperature. We present models with temperatures set by the
balance between starlight heating and radiative cooling, that are also in
vertical hydrostatic equilibrium. The planet has 20, 100, or 1000~M$_\oplus$,
ranging from barely enough to perturb the disk significantly, to clearing a
deep tidal gap. The hydrostatic balance strikingly alters the model disk's
appearance. The planet-carved gap's outer wall puffs up under starlight
heating, throwing a shadow across the disk beyond. The shadow appears in
scattered light as a dark ring that could be mistaken for a gap opened by
another more distant planet. The surface brightness contrast between outer wall
and shadow for the 1000-M$_\oplus$ planet is an order of magnitude greater than
a model neglecting the temperature disturbances. The shadow is so deep it
largely hides the planet-launched spiral wave's outer arm. Temperature
gradients are such that outer low-mass planets undergoing orbital migration
will converge within the shadow. Furthermore the temperature perturbations
affect the shape, size, and contrast of features at millimeter and centimeter
wavelengths. Thus radiative heating and cooling are key to the appearance of
protostellar disks with embedded planets.


title: The Restricted Ermolaev algebra and $F_4$

abstract:
  We investigate the simple Lie algebra of type $F_4$ over an algebraically
closed field of characteristic $p=3$. In this article we show that the
restricted Ermolaev algebra makes an appearance as a maximal subalgebra of
$F_4$.


title: Some new integrable systems of two-component fifth order equations

abstract:
  In this work we develop some fifth-order integrable coupled systems of weight
$0$ and $1$ which possess seventh-order symmetry. We establish four new
systems, where in some cases, related recursion operator and bi-Hamiltonian
formulations are given. We also investigate the integrability of the developed
systems.


title: Bootstrap equations for $\mathcal{N}=4$ SYM with defects

abstract:
  This paper focuses on the analysis of $4d$ $\mathcal{N}=4$ superconformal
theories in the presence of a defect from the point of view of the conformal
bootstrap. We will concentrate first on the case of codimension one, where the
defect is a boundary that preserves half of the supersymmetry. After studying
the constraints imposed by supersymmetry, we will obtain the Ward identities
associated to two-point functions of $\tfrac{1}{2}$-BPS operators and write
their solution as a superconformal block expansion. Due to a surprising
connection between spacetime and R-symmetry conformal blocks, our results not
only apply to $4d$ $\mathcal{N}=4$ superconformal theories with a boundary, but
also to three more systems that have the same symmetry algebra: $4d$
$\mathcal{N}=4$ superconformal theories with a line defect, $3d$
$\mathcal{N}=4$ superconformal theories with no defect, and $OSP(4^*|4)$
superconformal quantum mechanics. The superconformal algebra implies that all
these systems possess a closed subsector of operators in which the bootstrap
equations become polynomial constraints on the CFT data. We derive these
truncated equations and initiate the study of their solutions.


title:
A Bayesian Network approach to County-Level Corn Yield Prediction using
  historical data and expert knowledge

abstract:
  Crop yield forecasting is the methodology of predicting crop yields prior to
harvest. The availability of accurate yield prediction frameworks have enormous
implications from multiple standpoints, including impact on the crop commodity
futures markets, formulation of agricultural policy, as well as crop insurance
rating. The focus of this work is to construct a corn yield predictor at the
county scale. Corn yield (forecasting) depends on a complex, interconnected set
of variables that include economic, agricultural, management and meteorological
factors. Conventional forecasting is either knowledge-based computer programs
(that simulate plant-weather-soil-management interactions) coupled with
targeted surveys or statistical model based. The former is limited by the need
for painstaking calibration, while the latter is limited to univariate analysis
or similar simplifying assumptions that fail to capture the complex
interdependencies affecting yield. In this paper, we propose a data-driven
approach that is "gray box" i.e. that seamlessly utilizes expert knowledge in
constructing a statistical network model for corn yield forecasting. Our
multivariate gray box model is developed on Bayesian network analysis to build
a Directed Acyclic Graph (DAG) between predictors and yield. Starting from a
complete graph connecting various carefully chosen variables and yield, expert
knowledge is used to prune or strengthen edges connecting variables.
Subsequently the structure (connectivity and edge weights) of the DAG that
maximizes the likelihood of observing the training data is identified via
optimization. We curated an extensive set of historical data (1948-2012) for
each of the 99 counties in Iowa as data to train the model.


title:
Knot Invariants and M-Theory I: Hitchin Equations, Chern-Simons Actions,
  and the Surface Operators

abstract:
  Recently Witten introduced a type IIB brane construction with certain
boundary conditions to study knot invariants and Khovanov homology. The
essential ingredients used in his work are the topologically twisted N = 4
Yang-Mills theory, localization equations and surface operators. In this paper
we extend his construction in two possible ways. On one hand we show that a
slight modification of Witten's brane construction could lead, using certain
well defined duality transformations, to the model used by Ooguri-Vafa to study
knot invariants using gravity duals. On the other hand, we argue that both
these constructions, of Witten and of Ooguri-Vafa, lead to two different
seven-dimensional manifolds in M-theory from where the topological theories may
appear from certain twisting of the G-flux action. The non-abelian nature of
the topological action may also be studied if we take the wrapped M2-brane
states in the theory. We discuss explicit constructions of the
seven-dimensional manifolds in M-theory, and show that both the localization
equations and surface operators appear naturally from the Hamiltonian formalism
of the theories. Knots and link invariants are then constructed using M2-brane
states in both the models.


title:
SlangSD: Building and Using a Sentiment Dictionary of Slang Words for
  Short-Text Sentiment Classification

abstract:
  Sentiment in social media is increasingly considered as an important resource
for customer segmentation, market understanding, and tackling other
socio-economic issues. However, sentiment in social media is difficult to
measure since user-generated content is usually short and informal. Although
many traditional sentiment analysis methods have been proposed, identifying
slang sentiment words remains untackled. One of the reasons is that slang
sentiment words are not available in existing dictionaries or sentiment
lexicons. To this end, we propose to build the first sentiment dictionary of
slang words to aid sentiment analysis of social media content. It is laborious
and time-consuming to collect and label the sentiment polarity of a
comprehensive list of slang words. We present an approach to leverage web
resources to construct an extensive Slang Sentiment word Dictionary (SlangSD)
that is easy to maintain and extend. SlangSD is publicly available for research
purposes. We empirically show the advantages of using SlangSD, the newly-built
slang sentiment word dictionary for sentiment classification, and provide
examples demonstrating its ease of use with an existing sentiment system.


title:
Electron Spin Resonance at the Level of 10000 Spins Using Low Impedance
  Superconducting Resonators

abstract:
  We report on electron spin resonance (ESR) measurements of phosphorus donors
localized in a 200 square micron area below the inductive wire of a lumped
element superconducting resonator. By combining quantum limited parametric
amplification with a low impedance microwave resonator design we are able to
detect around 20000 spins with a signal-to-noise ratio (SNR) of 1 in a single
shot. The 150 Hz coupling strength between the resonator field and individual
spins is significantly larger than the 1 - 10 Hz coupling rates obtained with
typical coplanar waveguide resonator designs. Due to the larger coupling rate,
we find that spin relaxation is dominated by radiative decay into the resonator
and dependent upon the spin-resonator detuning, as predicted by Purcell.


title:
Females' Enrollment and Completion in Science, Technology, Engineering,
  and Mathematics Massive Open Online Courses

abstract:
  Massive Open Online Courses (MOOCs) have the potential to democratize
education by providing learners with access to rich sources of information.
However, evidence supporting this democratization across countries is limited.
We explored the question of democratization by investigating whether females
from different countries were more likely to enroll in and complete STEM MOOCs
compared with males. We found that whereas females were less likely to enroll
in STEM MOOCs, they were equally likely to complete them. We found smaller
gender gaps in STEM MOOC enrollment in less economically developed countries.
Further, females were more likely than males to complete STEM MOOCs in
countries identified as having a high potential to become the largest economies
in the 21st century.


title: A gate-variable spin current demultiplexer based on graphene

abstract:
  Spintronics, which utilizes spin as information carrier, is a promising
solution for nonvolatile memory and low-power computing in the post-Moore era.
An important challenge is to realize long distance spin transport, together
with efficient manipulation of spin current for novel logic-processing
applications. Here, we describe a gate-variable spin current demultiplexer
(GSDM) based on graphene, serving as a fundamental building block of
reconfigurable spin current logic circuits. The concept relies on electrical
gating of carrier density dependent conductivity and spin diffusion length in
graphene. As a demo, GSDM is realized for both single-layer and bilayer
graphene. The distribution and propagation of spin current in the two branches
of GSDM depend on spin relaxation characteristics of graphene. Compared with
Elliot-Yafet spin relaxation mechanism, D'yakonov-Perel mechanism results in
more appreciable gate-tuning performance. These unique features of GSDM would
give rise to abundant spin logic applications, such as on-chip spin current
modulators and reconfigurable spin logic circuits.


title:
Successive Convexification of Non-Convex Optimal Control Problems and
  Its Convergence Properties

abstract:
  This paper presents an algorithm to solve non-convex optimal control
problems, where non-convexity can arise from nonlinear dynamics, and non-convex
state and control constraints. This paper assumes that the state and control
constraints are already convex or convexified, the proposed algorithm
convexifies the nonlinear dynamics, via a linearization, in a successive
manner. Thus at each succession, a convex optimal control subproblem is solved.
Since the dynamics are linearized and other constraints are convex, after a
discretization, the subproblem can be expressed as a finite dimensional convex
programming subproblem. Since convex optimization problems can be solved very
efficiently, especially with custom solvers, this subproblem can be solved in
time-critical applications, such as real-time path planning for autonomous
vehicles. Several safe-guarding techniques are incorporated into the algorithm,
namely virtual control and trust regions, which add another layer of
algorithmic robustness. A convergence analysis is presented in continuous- time
setting. By doing so, our convergence results will be independent from any
numerical schemes used for discretization. Numerical simulations are performed
for an illustrative trajectory optimization example.


title:
Improving LIGO calibration accuracy by tracking and compensating for
  slow temporal variations

abstract:
  Calibration of the second-generation LIGO interferometric gravitational-wave
detectors employs a method that uses injected periodic modulations to track and
compensate for slow temporal variations in the differential length response of
the instruments. These detectors utilize feedback control loops to maintain
resonance conditions by suppressing differential arm length variations. We
describe how the sensing and actuation functions of these servo loops are
parameterized and how the slow variations in these parameters are quantified
using the injected modulations. We report the results of applying this method
to the LIGO detectors and show that it significantly reduces systematic errors
in their calibrated outputs.


title:
Quantum routing of single optical photons with a superconducting flux
  qubit

abstract:
  Controlling and swapping quantum information in a quantum coherent way
between the microwave and optical regimes is essential for building long-range
superconducting quantum networks but extremely challenging. We propose a hybrid
quantum interface between the microwave and optical domains where the
propagation of a single-photon pulse along a nanowaveguide is controlled in a
coherent way by tuning electromagnetically induced transparency window with the
quantum state of a flux qubit. The qubit can route a single-photon pulse with a
single spin in nanodiamond into a quantum superposition of paths without the
aid of an optical cavity - simplifying the setup. By preparing the flux qubit
in a superposition state our cavity-less scheme creates a hybrid state-path
entanglement between a flying single optical photon and a static
superconducting qubit, and can conduct heralded quantum state transfer via
measurement.


title: Surface tension of molecular liquids: Lattice gas approach

abstract:
  The approach of global isomorphism between the fluid and the Ising model is
applied to obtain an expression for the surface tension of the Lennard-Jones
fluid on the basis of the information about the Ising model. This is done in a
broad interval of temperatures along the phase coexistence, and is valid both
in 2D and 3D. The relation between the critical amplitudes of the surface
tension of the fluid and the Ising model is derived in the vicinity of the
critical point. The obtained theoretical estimates agree well with the
literature results for the surface tension. The methodology is demonstrated for
the 2D LJ fluid on the basis of the exact solution of the 2D Ising model and is
tested for the 3D LJ fluid. As a result, an expression for the surface tension
without any fitting parameter is derived.


title: IM2CAD

abstract:
  Given a single photo of a room and a large database of furniture CAD models,
our goal is to reconstruct a scene that is as similar as possible to the scene
depicted in the photograph, and composed of objects drawn from the database. We
present a completely automatic system to address this IM2CAD problem that
produces high quality results on challenging imagery from interior home design
and remodeling websites. Our approach iteratively optimizes the placement and
scale of objects in the room to best match scene renderings to the input photo,
using image comparison metrics trained via deep convolutional neural nets. By
operating jointly on the full scene at once, we account for inter-object
occlusions. We also show the applicability of our method in standard scene
understanding benchmarks where we obtain significant improvement.


title: Hybrid CPU-GPU Framework for Network Motifs

abstract:
  Massively parallel architectures such as the GPU are becoming increasingly
important due to the recent proliferation of data. In this paper, we propose a
key class of hybrid parallel graphlet algorithms that leverages multiple CPUs
and GPUs simultaneously for computing k-vertex induced subgraph statistics
(called graphlets). In addition to the hybrid multi-core CPU-GPU framework, we
also investigate single GPU methods (using multiple cores) and multi-GPU
methods that leverage all available GPUs simultaneously for computing induced
subgraph statistics. Both methods leverage GPU devices only, whereas the hybrid
multi-core CPU-GPU framework leverages all available multi-core CPUs and
multiple GPUs for computing graphlets in large networks. Compared to recent
approaches, our methods are orders of magnitude faster, while also more cost
effective enjoying superior performance per capita and per watt. In particular,
the methods are up to 300 times faster than the recent state-of-the-art method.
To the best of our knowledge, this is the first work to leverage multiple CPUs
and GPUs simultaneously for computing induced subgraph statistics.


title:
Constraining primordial and gravitational mode coupling with the
  position-dependent bispectrum of the large-scale structure

abstract:
  We develop and study the position-dependent bispectrum. It is a
generalization of the recently proposed position-dependent power spectrum
method of measuring the squeezed-limit bispectrum. The position-dependent
bispectrum can similarly be used to measure the squeezed-limit trispectrum in
which one of the wavelengths is much longer than the other three. In this work,
we will mainly consider the case in which the three smaller wavelengths are
nearly the same (the equilateral configuration). We use the Fisher information
matrix to forecast constraints on bias parameters and the amplitude of
primordial trispectra from the position-dependent bispectrum method. We find
that the method can constrain the local-type $g_{\rm NL}$ at a level of
$\sigma(g_{\rm NL}^{\rm local}) \approx 3 \times 10^5$ for a large volume
SPHEREx-like survey; improvements can be expected by including all the
triangular configurations of the bispectra rather than just the equilateral
configuration. However, the same measurement would also constrain a much larger
family of trispectra than local $g_{\rm NL}$ model. We discuss the implications
of the forecasted reach of future surveys in terms of super cosmic variance
uncertainties from primordial non-Gaussianities.


title: Are Today's SDN Controllers Ready for Primetime?

abstract:
  SDN efficiency is driven by the ability of controllers to process small
packets based on a global view of the network. The goal of such controllers is
thus to treat new flows coming from hundreds of switches in a timely fashion.
In this paper, we show this ideal remains impossible through the most extensive
evaluation of SDN controllers. We evaluated five state-of-the-art SDN
controllers and discovered that the most efficient one spends a fifth of his
time in packet serialization. More dramatically, we show that this limitation
is inherent to the object oriented design principle of these controllers. They
all treat each single packet as an individual object, a limitation that induces
an unaffordable per-packet overhead. To eliminate the responsibility of the
hardware from our results, we ported these controllers on a network-efficient
architecture, Tilera, and showed even worse performance. We thus argue for an
in-depth rethinking of the design of the SDN controller into a lower level
software that leverages both operating system optimizations and modern hardware
features.


title: A novel probe of chiral restoration in nuclear medium

abstract:
  We propose measuring the mass shift and width broadening of the $f_1(1285)$
meson together with those of the $\omega$ from a nuclear target as a means to
experimentally probe the partial restoration of chiral symmetry inside the
nuclear matter. The relation between the order parameter of chiral symmetry and
the difference in the correlation functions of the $f_1(1285)$ current and the
$\omega$ current is discussed in the limit where the disconnected diagrams are
neglected. A QCD sum rule analysis of the $f_1(1285)$ meson mass leads to about
100 MeV attraction in nuclear matter, which can be probed in future
experiments.


title:
Generic Inference on Quantile and Quantile Effect Functions for Discrete
  Outcomes

abstract:
  Quantile and quantile effect functions are important tools for descriptive
and causal analyses due to their natural and intuitive interpretation. Existing
inference methods for these functions do not apply to discrete random
variables. This paper offers a simple, practical construction of simultaneous
confidence bands for quantile and quantile effect functions of possibly
discrete random variables. It is based on a natural transformation of
simultaneous confidence bands for distribution functions, which are readily
available for many problems. The construction is generic and does not depend on
the nature of the underlying problem. It works in conjunction with parametric,
semiparametric, and nonparametric modeling methods for observed and
counterfactual distributions, and does not depend on the sampling scheme. We
apply our method to characterize the distributional impact of insurance
coverage on health care utilization and obtain the distributional decomposition
of the racial test score gap. We find that universal insurance coverage
increases the number of doctor visits across the entire distribution, and that
the racial test score gap is small at early ages but grows with age due to
socio economic factors affecting child development especially at the top of the
distribution. These are new, interesting empirical findings that complement
previous analyses that focused on mean effects only. In both applications, the
outcomes of interest are discrete rendering existing inference methods invalid
for obtaining uniform confidence bands for observed and counterfactual quantile
functions and for their difference -- the quantile effects functions.


title:
A Systematic Approach for Cross-source Point Cloud Registration by
  Preserving Macro and Micro Structures

abstract:
  We propose a systematic approach for registering cross-source point clouds.
The compelling need for cross-source point cloud registration is motivated by
the rapid development of a variety of 3D sensing techniques, but many existing
registration methods face critical challenges as a result of the large
variations in cross-source point clouds. This paper therefore illustrates a
novel registration method which successfully aligns two cross-source point
clouds in the presence of significant missing data, large variations in point
density, scale difference and so on. The robustness of the method is attributed
to the extraction of macro and micro structures. Our work has three main
contributions: (1) a systematic pipeline to deal with cross-source point cloud
registration; (2) a graph construction method to maintain macro and micro
structures; (3) a new graph matching method is proposed which considers the
global geometric constraint to robustly register these variable graphs.
Compared to most of the related methods, the experiments show that the proposed
method successfully registers in cross-source datasets, while other methods
have difficulty achieving satisfactory results. The proposed method also shows
great ability in same-source datasets.


title: Solution to the sign problem in a frustrated quantum impurity model

abstract:
  In this work we solve the sign problem of a frustrated quantum impurity model
consisting of three quantum spin-half chains interacting through an
anti-ferromagnetic Heisenberg interaction at one end. We first map the model
into a repulsive Hubbard model of spin-half fermions hopping on three
independent one dimensional chains that interact through a triangular hopping
at one end. We then convert the fermion model into an inhomogeneous one
dimensional model and express the partition function as a weighted sum over
fermion worldline configurations. By imposing a pairing of fermion worldlines
in half the space we show that all negative weight configurations can be
eliminated. This pairing naturally leads to the original frustrated quantum
spin model at half filling and thus solves its sign problem.


title: Filling the gaps smoothly

abstract:
  The calibration of a local volatility models to a given set of option prices
is a classical problem of mathematical finance. It was considered in multiple
papers where various solutions were proposed. In this paper an extension of the
approach proposed in LiptonSepp2011 is developed by i) replacing a piecewise
constant local variance construction with a piecewise linear one, and ii)
allowing non-zero interest rates and dividend yields. Our approach remains
analytically tractable; it combines the Laplace transform in time with an
analytical solution of the resulting spatial equations in terms of Kummer's
degenerate hypergeometric functions.


title: Commuting differential operators of rank 2 with rational coefficients

abstract:
  In this paper we find new self-adjoint commuting operators of rank 2 with
rational coefficients and prove that any elliptic and hyperelliptic curves of
genus 2 are spectral curves of commuting operators with rational coefficients.
Also the case when curves of genus 3 are spectral curves of commuting operators
with rational coefficients is studied.


title:
Single-Photon Switching and Entanglement of Solid-State Qubits in an
  Integrated Nanophotonic System

abstract:
  Efficient interfaces between photons and quantum emitters form the basis for
quantum networks and enable nonlinear optical devices operating at the
single-photon level. We demonstrate an integrated platform for scalable quantum
nanophotonics based on silicon-vacancy (SiV) color centers coupled to nanoscale
diamond devices. By placing SiV centers inside diamond photonic crystal
cavities, we realize a quantum-optical switch controlled by a single color
center. We control the switch using SiV metastable orbital states and verify
optical switching at the single-photon level by using photon correlation
measurements. We use Raman transitions to realize a single-photon source with a
tunable frequency and bandwidth in a diamond waveguide. Finally, we create
entanglement between two SiV centers by detecting indistinguishable Raman
photons emitted into a single waveguide. Entanglement is verified using a novel
superradiant feature observed in photon correlation measurements, paving the
way for the realization of quantum networks.


title: Full Resolution Image Compression with Recurrent Neural Networks

abstract:
  This paper presents a set of full-resolution lossy image compression methods
based on neural networks. Each of the architectures we describe can provide
variable compression rates during deployment without requiring retraining of
the network: each network need only be trained once. All of our architectures
consist of a recurrent neural network (RNN)-based encoder and decoder, a
binarizer, and a neural network for entropy coding. We compare RNN types (LSTM,
associative LSTM) and introduce a new hybrid of GRU and ResNet. We also study
"one-shot" versus additive reconstruction architectures and introduce a new
scaled-additive framework. We compare to previous work, showing improvements of
4.3%-8.8% AUC (area under the rate-distortion curve), depending on the
perceptual metric used. As far as we know, this is the first neural network
architecture that is able to outperform JPEG at image compression across most
bitrates on the rate-distortion curve on the Kodak dataset images, with and
without the aid of entropy coding.


title: The Chandra COSMOS-Legacy survey: Source X-ray spectral properties

abstract:
  We present the X-ray spectral analysis of the 1855 extragalactic sources in
the Chandra COSMOS-Legacy survey catalog having more than 30 net counts in the
0.5-7 keV band. 38% of the sources are optically classified Type 1 active
galactic nuclei (AGN), 60% are Type 2 AGN and 2% are passive, low-redshift
galaxies. We study the distribution of AGN photon index and of the intrinsic
absorption N(H,z) based on the sources optical classification: Type 1 have a
slightly steeper mean photon index than Type 2 AGN, which on the other hand
have average intrinsic absorption ~3 times higher than Type 1 AGN. We find that
~15% of Type 1 AGN have N(H,z)>1E22 cm^(-2), i.e., are obscured according to
the X-ray spectral fitting; the vast majority of these sources have
L(2-10keV)>$1E44 erg/s. The existence of these objects suggests that optical
and X-ray obscuration can be caused by different phenomena, the X-ray
obscuration being for example caused by dust-free material surrounding the
inner part of the nuclei. ~18% of Type 2 AGN have N(H,z)<1E22 cm^(-2), and most
of these sources have low X-ray luminosities (L(2-10keV)<$1E43 erg/s). We
expect a part of these sources to be low-accretion, unobscured AGN lacking of
broad emission lines. Finally, we also find a direct proportional trend between
N(H,z) and host galaxy mass and star formation rate, although part of this
trend is due to a redshift selection effect.


title:
Experimental demonstration of Layered/Enhanced ACO-OFDM in short haul
  optical fiber transmission link

abstract:
  Asymmetrically clipped optical orthogonal frequency division multiplexing
(ACO-OFDM) is theoretically more power efficient but less spectrally efficient
than DC-bias OFDM (DCO-OFDM), with less power allocating to the informationless
bias component by only using odd index sub-carriers. Layered/Enhanced
asymmetrically clipped optical orthogonal frequency division multiplexing
(L/E-ACO-OFDM) has been proposed to increase the spectral efficiency of
ACO-OFDM. In this letter, we experimentally demonstrate a 30-km single mode
fiber transmission using L/E-ACO-OFDM at 4.375 Gbits/s. Using a Volterra filter
based equalizer, 2-dB and 1.5-dB Q-factor improvements for L/E-ACO-OFDM
comparing with DCO-OFDM can be obtained in back-to-back and 30-km fiber
transmission respectively.


title:
Effective Multi-step Temporal-Difference Learning for Non-Linear
  Function Approximation

abstract:
  Multi-step temporal-difference (TD) learning, where the update targets
contain information from multiple time steps ahead, is one of the most popular
forms of TD learning for linear function approximation. The reason is that
multi-step methods often yield substantially better performance than their
single-step counter-parts, due to a lower bias of the update targets. For
non-linear function approximation, however, single-step methods appear to be
the norm. Part of the reason could be that on many domains the popular
multi-step methods TD($\lambda$) and Sarsa($\lambda$) do not perform well when
combined with non-linear function approximation. In particular, they are very
susceptible to divergence of value estimates. In this paper, we identify the
reason behind this. Furthermore, based on our analysis, we propose a new
multi-step TD method for non-linear function approximation that addresses this
issue. We confirm the effectiveness of our method using two benchmark tasks
with neural networks as function approximation.


title: Conditional Sparse Linear Regression

abstract:
  Machine learning and statistics typically focus on building models that
capture the vast majority of the data, possibly ignoring a small subset of data
as "noise" or "outliers." By contrast, here we consider the problem of jointly
identifying a significant (but perhaps small) segment of a population in which
there is a highly sparse linear regression fit, together with the coefficients
for the linear fit. We contend that such tasks are of interest both because the
models themselves may be able to achieve better predictions in such special
cases, but also because they may aid our understanding of the data. We give
algorithms for such problems under the sup norm, when this unknown segment of
the population is described by a k-DNF condition and the regression fit is
s-sparse for constant k and s. For the variants of this problem when the
regression fit is not so sparse or using expected error, we also give a
preliminary algorithm and highlight the question as a challenge for future
work.


title:
Rogue wave triggered at a critical frequency of a nonlinear resonant
  medium

abstract:
  We consider a two-level atomic system, interacting with an electromagnetic
field controlled in amplitude and frequency by a high intensity laser. We show
that the amplitude of the induced electric field, admits an envelope profile
corresponding to a breather soliton. We demonstrate that this soliton can
propagate with any frequency shift with respect to that of the control laser,
except a critical frequency, at which the system undergoes a structural
discontinuity that transforms the breather in a rogue wave. A mechanism of
generation of rogue waves by means of an intense laser field is thus revealed.