TY - JOUR

T1 - "Hot entanglement"? - A nonequilibrium quantum field theory scrutiny

AU - Hsiang, J. T.

AU - Hu, B. L.

N1 - Publisher Copyright:
© 2015 The Authors.

PY - 2015/11/12

Y1 - 2015/11/12

N2 - The possibility of maintaining entanglement in a quantum system at finite, even high, temperatures - the so-called 'hot entanglement' - has obvious practical interest, but also requires closer theoretical scrutiny. Since quantum entanglement in a system evolves in time and is continuously subjected to environmental degradation, a nonequilibrium description by way of open quantum systems is called for. To identify the key issues and the contributing factors that may permit 'hot entanglement' to exist, or the lack thereof, we carry out a model study of two spatially-separated, coupled oscillators in a shared bath depicted by a finite-temperature scalar field. From the Langevin equations we derived for the normal modes and the entanglement measure constructed from the covariance matrix we examine the interplay between direct coupling, field-induced interaction and finite separation on the structure of late-time entanglement. We show that the coupling between oscillators plays a crucial role in sustaining entanglement at intermediate temperatures and over finite separations. In contrast, the field-induced interaction between the oscillators which is a non-Markovian effect becomes very ineffective at high temperature. We determine the critical temperature above which entanglement disappears to be bounded in the leading order by the inverse frequency of the center-of-mass mode of the reduced oscillator system, a result not unexpected, which rules out hot entanglement in such settings.

AB - The possibility of maintaining entanglement in a quantum system at finite, even high, temperatures - the so-called 'hot entanglement' - has obvious practical interest, but also requires closer theoretical scrutiny. Since quantum entanglement in a system evolves in time and is continuously subjected to environmental degradation, a nonequilibrium description by way of open quantum systems is called for. To identify the key issues and the contributing factors that may permit 'hot entanglement' to exist, or the lack thereof, we carry out a model study of two spatially-separated, coupled oscillators in a shared bath depicted by a finite-temperature scalar field. From the Langevin equations we derived for the normal modes and the entanglement measure constructed from the covariance matrix we examine the interplay between direct coupling, field-induced interaction and finite separation on the structure of late-time entanglement. We show that the coupling between oscillators plays a crucial role in sustaining entanglement at intermediate temperatures and over finite separations. In contrast, the field-induced interaction between the oscillators which is a non-Markovian effect becomes very ineffective at high temperature. We determine the critical temperature above which entanglement disappears to be bounded in the leading order by the inverse frequency of the center-of-mass mode of the reduced oscillator system, a result not unexpected, which rules out hot entanglement in such settings.

KW - Nonequilibrium quantum dynamics

KW - Quantum field theory

KW - Quantum open systems

KW - Thermal entanglement

UR - http://www.scopus.com/inward/record.url?scp=84943271132&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2015.09.047

DO - 10.1016/j.physletb.2015.09.047

M3 - 期刊論文

AN - SCOPUS:84943271132

SN - 0370-2693

VL - 750

SP - 396

EP - 400

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

ER -