title: Strong local passivity in finite quantum systems.
abstract: Passive states of quantum systems are states from which no system energy can be extracted by any cyclic (unitary) process. Gibbs states of all temperatures are passive. Strong local (SL) passive states are defined to allow any general quantum operation, but the operation is required to be local, being applied only to a specific subsystem. Any mixture of eigenstates in a system-dependent neighborhood of a nondegenerate entangled ground state is found to be SL passive. In particular, Gibbs states are SL passive with respect to a subsystem only at or below a critical system-dependent temperature. SL passivity is associated in many-body systems with the presence of ground state entanglement in a way suggestive of collective quantum phenomena such as quantum phase transitions, superconductivity, and the quantum Hall effect. The presence of SL passivity is detailed for some simple spin systems where it is found that SL passivity is neither confined to systems of only a few particles nor limited to the near vicinity of the ground state.
authors.affiliation: Department of Mathematics, Bucknell University, Lewisburg, Pennsylvania 17837, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Frey
authors.affiliation: Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Funo
authors.affiliation: Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hotta
mesh_terms: D011789:Quantum Theory