TY - JOUR

T1 - Separability gap and large-deviation entanglement criterion

AU - Czartowski, Jakub

AU - Szymański, Konrad

AU - Gardas, Bartłomiej

AU - Fyodorov, Yan V.

AU - Zyczkowski, Karol

PY - 2019/10/28

Y1 - 2019/10/28

N2 - For a given Hamiltonian H on a multipartite quantum system, one is interested in finding the energy E0 of its ground state. In the separability approximation, arising as a natural consequence of measurement in a separable basis, one looks for the minimal expectation value λmin- of H among all product states. For several concrete model Hamiltonians, we investigate the difference λmin - -E0, called the separability gap, which vanishes if the ground state has a product structure. In the generic case of a random Hermitian matrix of the Gaussian orthogonal ensemble, we find explicit bounds for the size of the gap which depend on the number of subsystems and hold with probability one. This implies an effective entanglement criterion applicable for any multipartite quantum system: If an expectation value of a typical observable of a given state is sufficiently distant from the average value, the state is almost surely entangled.

AB - For a given Hamiltonian H on a multipartite quantum system, one is interested in finding the energy E0 of its ground state. In the separability approximation, arising as a natural consequence of measurement in a separable basis, one looks for the minimal expectation value λmin- of H among all product states. For several concrete model Hamiltonians, we investigate the difference λmin - -E0, called the separability gap, which vanishes if the ground state has a product structure. In the generic case of a random Hermitian matrix of the Gaussian orthogonal ensemble, we find explicit bounds for the size of the gap which depend on the number of subsystems and hold with probability one. This implies an effective entanglement criterion applicable for any multipartite quantum system: If an expectation value of a typical observable of a given state is sufficiently distant from the average value, the state is almost surely entangled.

UR - http://www.scopus.com/inward/record.url?scp=85074440305&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.100.042326

DO - 10.1103/PhysRevA.100.042326

M3 - Article

AN - SCOPUS:85074440305

SN - 1050-2947

VL - 100

JO - Physical Review A (Atomic, Molecular and Optical Physics)

JF - Physical Review A (Atomic, Molecular and Optical Physics)

IS - 4

M1 - 042326

ER -