arXiv:1310.1236 · Condensed Matter Physics

Bath dynamics in an exactly solvable qubit model with initial qubit-environment correlations

V. V. Ignatyuk, Morozov

Published Jan 1, 2013• 10 citations

Abstract

We study the bath dynamics in the dephasing model of a two-state quantum system (qubit) coupled to an environment of harmonic oscillators.This model was shown [Morozov et al., Phys.Rev. A, 2012 85, 022101] to admit the analytic solution for the qubit and environment dynamics.Using this solution, we derive the exact expression for the bath reduced density matrix in the presence of initial qubit-environment correlations.We obtain the non-equilibrium phonon distribution function and discuss in detail the time behavior of the bath energy.It is shown that only the inclusion of dynamic correlations between the qubit and the bath ensures the proper time behavior of the quantity which may be interpreted as the "environment energy".

DOI: 10.5488/cmp.16.34001

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arXiv:1310.1236 · Condensed Matter Physics

Bath dynamics in an exactly solvable qubit model with initial qubit-environment correlations

V. V. Ignatyuk, Morozov

Published Jan 1, 2013• 10 citations

arXiv HTML PDF

Abstract

DOI: 10.5488/cmp.16.34001

Related papers

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X

state and the environment. Applying these criteria to initial Werner states, we find that entanglement between the system and environment is built up in time for temperatures below a certain critical temperature

{T}_{\mathrm{crit}}

. On the other hand, the total state remains separable during those short times that are relevant for decoherence and loss of entanglement in the two-qubit state. Close to

{T}_{\mathrm{crit}}

the SE correlations oscillate between separable and entangled. Even though these oscillations are also observed in the entanglement between the two qubits, no simple relation between the loss of entanglement in the two-qubit system and the build-up of entanglement between the system and environment is found.

P_x(t)

and

C_x(t)

. We find that integer values of

A

(coupling strength) or

s

(bath exponent) has distinctive long time asymptotic behaviors of

P_x(t)

and

C_x(t)

from those of the non-integer values, accompanied with a diverging crossover time scale. We also find that the non-Hermitian environment tends to suppress the decoherence of qubit for all values of

A

and

s

, in contrast to the conclusion of Dey et al . [Phys. Lett. A 383, 125931 (2019)]. Our results show the potential of the non-Hermitian environmental engineering for suppressing the decoherence of qubit.