Pairwise tomography networks for many-body quantum systems
We introduce the concept of pairwise tomography networks to characterise
quantum properties in many-body systems and demonstrate an efficient protocol
to measure them experimentally. Pairwise tomography networks are generators of
multiplex networks where each layer represents the graph of a relevant
quantifier such as, e.g., concurrence, quantum discord, purity, quantum mutual
information, or classical correlations. We propose a measurement scheme to
perform two-qubit tomography of all pairs showing exponential improvement in
the number of qubits $N$ with respect to previously existing methods. We
illustrate the usefulness of our approach by means of several examples
revealing its potential impact to quantum computation, communication and
simulation. We perform a proof-of-principle experiment demonstrating pairwise
tomography networks of $W$ states on IBM Q devices.
Guillermo García-Pérez Matteo A. C. Rossi Boris Sokolov Elsi-Mari Borrelli Sabrina Maniscalco