Exact Analysis of Disentanglement for Continuous Variable Systems and Application to a Two-Body System at Zero Temperature in an Arbitrary Heat Bath

We consider the case of a pair of particles initially in a superposition state corresponding to a separated pair of wave packets. In contrast to a previous related work, we avoid a master equation approach and we calculate exactly the time development of this non-Gaussian state due to interaction with an arbitrary heat bath. We find that coherence decays continuously, as expected. We then investigate entanglement and find that at a finite time the system becomes separable (not entangled). Thus, we see that entanglement sudden death is also prevalent in continuous variable systems which should raise concern for the designers of entangled systems.

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Thermodynamics at zero temperature: inequalities for the ground state of a quantum many-body system

Physics Letters A ◽

10.1016/j.physleta.2021.127637 ◽

2021 ◽

pp. 127637

Author(s):

N. Il'in ◽

E. Shpagina ◽

O. Lychkovskiy

Keyword(s):

Ground State ◽

Zero Temperature ◽

Body System ◽

Many Body

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Wave equation for dissipative motion

Canadian Journal of Physics ◽

10.1139/p91-184 ◽

1991 ◽

Vol 69 (10) ◽

pp. 1225-1232 ◽

Cited By ~ 1

Author(s):

M. Razavy

Keyword(s):

Wave Equation ◽

Single Particle ◽

Equations Of Motion ◽

Dissipative System ◽

Heat Bath ◽

Initial Position ◽

Time Dependent ◽

Reduced Form ◽

Body System ◽

Many Body

From a quantized many-body system a wave equation for the motion of a particle linearly coupled to a heat bath is derived. The effective Hamiltonian describing the motion of the single particle is explicitly time dependent, and for a quadratic potential, has a simple dependence on the initial position and momentum of the particle. For the case of dissipative harmonic motion, a time-dependent wave equation is derived and the ground-state wave function is determined. It is also shown that if the equations of motion for the many-body system is Galilean invariant, the reduced form of equation of motion for the single particle is not. However a generalized form of transformation for the position and momentum operators, to a coordinate system moving with constant velocity, is obtained, which reduces to the Galilean transformation when the coupling to the dissipative system is turned off.

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Unitarity conditions for a many-body system at zero temperature

Theoretical and Mathematical Physics ◽

10.1007/bf01028532 ◽

1970 ◽

Vol 3 (3) ◽

pp. 616-625 ◽

Cited By ~ 1

Author(s):

S. L. Ginzburg ◽

S. V. Maleev

Keyword(s):

Zero Temperature ◽

Body System ◽

Many Body

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Dynamic of the Gaussian quantum discord and effect of non-Markovian degree

Canadian Journal of Physics ◽

10.1139/cjp-2014-0258 ◽

2015 ◽

Vol 93 (4) ◽

pp. 481-485

Author(s):

Xin Liu ◽

Wei Wu ◽

Changkui Hu

Keyword(s):

Markov Process ◽

Experimental Method ◽

Dynamic Characteristic ◽

Quantum Discord ◽

Thermal State ◽

Quantum Correlations ◽

Continuous Variable ◽

Zero Temperature ◽

The Relationship ◽

Gaussian Quantum Discord

We study the dynamic of the Gaussian quantum discord in a continuous-variable system subject to a common non-Markovian environment with zero-temperature. By considering an initial two-mode Gaussian symmetric squeezed thermal state, we show that Gaussian discord has a very different dynamic characteristic in a non-Markovian evolution versus a Markov process, and can be created by the memory effect, which features non-Markovianity. We also study the relationship between Gaussian discord and the non-Markovian degree of the environment. The results may offer us an effective experimental method to get more quantum correlations.

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Infrared finiteness of a complete theory of charged scalars and fermions at finite temperature

The European Physical Journal C ◽

10.1140/epjc/s10052-020-08498-3 ◽

2020 ◽

Vol 80 (10) ◽

Author(s):

Pritam Sen ◽

D. Indumathi ◽

Debajyoti Choudhury

Keyword(s):

Finite Temperature ◽

Thermal Field ◽

Heat Bath ◽

Specific Form ◽

Field Theories ◽

Real Photon ◽

Scalar Interaction ◽

Zero Temperature ◽

Neutral Fermion ◽

Photon Interactions

AbstractIt is known that the infrared (IR) divergences accruing from pure fermion–photon interactions at finite temperature cancel to all orders in perturbation theory. The corresponding infrared finiteness of scalar thermal QED has also been established recently. Here, we study the IR behaviour, at finite temperature, of theories where charged scalars and fermions interact with neutrals that could potentially be dark matter candidates. Such thermal field theories contain both linear and sub-leading logarithmic divergences. We prove that the theory is IR-finite to all orders in perturbation, with the divergences cancelling order by order between virtual and real photon corrections, when both absorption and emission of photons from and into the heat bath are taken into account. The calculation follows closely the technique used by Grammer and Yennie for zero temperature field theory. The result is generic and applicable to a variety of models, independent of the specific form of the neutral-fermion–scalar interaction vertex.

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Bounding the resources for thermalizing many-body localized systems

Communications Physics ◽

10.1038/s42005-020-00503-1 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Carlo Sparaciari ◽

Marcel Goihl ◽

Paul Boes ◽

Jens Eisert ◽

Nelly Huei Ying Ng

Keyword(s):

Heat Bath ◽

Quantum Systems ◽

External Heat ◽

Upper And Lower Bounds ◽

Body System ◽

Heisenberg Chain ◽

Many Body ◽

Physical Systems ◽

Collision Models ◽

Standing Question

AbstractUnderstanding under which conditions physical systems thermalize is a long-standing question in many-body physics. While generic quantum systems thermalize, there are known instances where thermalization is hindered, for example in many-body localized (MBL) systems. Here we introduce a class of stochastic collision models coupling a many-body system out of thermal equilibrium to an external heat bath. We derive upper and lower bounds on the size of the bath required to thermalize the system via such models, under certain assumptions on the Hamiltonian. We use these bounds, expressed in terms of the max-relative entropy, to characterize the robustness of MBL systems against externally-induced thermalization. Our bounds are derived within the framework of resource theories using the convex split lemma, a recent tool developed in quantum information. We apply our results to the disordered Heisenberg chain, and numerically study the robustness of its MBL phase in terms of the required bath size.

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