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Modern Physics Letters A

Quantum coherence, degree of mixedness and entropy squeezing of a two-level atom with the presence of the phase-noisy laser

K. Berrada, Mariam Algarni, S. Abdel‐Khalek

Published Dec 31, 2024• 0 citations
Publisher

Abstract

In this paper, we quantitatively examine the dynamics of quantum resources, such as quantum coherence, degree of mixedness, fidelity, and the atomic entropy squeezing, in a quantum system of a two-level atom (TLA) driven by a phase noise laser (PNL) within the context of non-Markovian dynamics. The [Formula: see text] norm is used to quantify coherence, linear entropy to measure the degree of TLA mixedness, and entropy to detect the atomic squeezing. We demonstrate how these quantum resources can be controlled through a suitable selection of model parameters. Furthermore, we provide the optimal conditions required to manipulate these quantum resources based on changes in the damping coupling. Finally, we discuss the relationships among the quantum resources in the present quantum model.

DOI
10.1142/s0217732324502031

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In this paper, we quantitatively examine the dynamics of quantum resources, such as quantum coherence, degree of mixedness, fidelity, and the atomic entropy squeezing, in a quantum system of a two-level atom (TLA) driven by a phase noise laser (PNL) within the context of non-Markovian dynamics. The [Formula: see text] norm is used to quantify coherence, linear entropy to measure the degree of TLA mixedness, and entropy to detect the atomic squeezing. We demonstrate how these quantum resources can be controlled through a suitable selection of model parameters. Furthermore, we provide the optimal conditions required to manipulate these quantum resources based on changes in the damping coupling. Finally, we discuss the relationships among the quantum resources in the present quantum model.
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Abstract Based on the Heisenberg uncertainty relation and the entropy uncertainty relation, the nonclassical effects described by variance squeezing and entropy squeezing for a two-level system driven by a classical phase noisy laser are investigated. Analytical expressions of the variance squeezing and entropy squeezing subjected to the classical phase noisy laser are derived. Our results show that the nonclassical squeezed effects can be protected for a long time in both the Markovian and non-Markovian regions by controlling the ratios between the phase diffusion rate and the system-laser coupling strength. Besides, we also develop an effective strategy to enhance the nonclassical squeezed effects with the help of filtering operation. The underlying physical mechanism to enhance the squeezing is also analyzed.
We examine the impact of the non-Markovian environment on the dynamical behavior of the quantum coherence and entropy squeezing considering a two-level atomic system (qubit) immersed in a reservoir with zero-temperature for two types of non-Markovian environments. We consider a cavity little off-resonance with the transition frequency of the qubit and the case of a non-perfect photonic band gap (PBG). We show that the amount of coherence is dependent on the structure of the environment and influenced through the memory effects. We obtain that the delay and revival of the coherence loss might take place by controlling the detuning of the cavity-qubit system. Whereas, a partial coherence trapping occurs in non-ideal PBG and the decrease of the gap width will destroy the coherence. On the other hand, we show the situation for which the squeezing is occurring and enhanced with respect to the main parameters for the system. Finally, we display the monotonic dependence of the quantum coherence and squeezing on the main model parameters.
We propose an approach to measuring non-Markovianity of an open two-level system from quantum coherence perspective including l1 norm of coherence and quantum relative entropy of coherence, and derive corresponding non-Markovian conditions. Further, as a particular application, non-Markovian conditions of an open two-level system undergoing phase damping channel, random unitary channel and amplitude damping channel, respectively are investigated. Specifically speaking, for the three channels we obtain non-Markovian conditions based on l1 norm of coherence at any initial state of system, and find that non-Markovian conditions are the same as the conditions of other measurements, i.e., information back-flow, divisibility and quantum mutual entropy for the phase damping channel and amplitude damping channel, but non-Markovian conditions new and different from the conditions of other measurements for random unitary channel. On the other hand, for phase damping channel we obtain non-Markovian conditions based on quantum relative entropy of coherence at any initial state of system, which are the same as the conditions of other measures, i.e., information back-flow, divisibility and quantum mutual entropy. However, for the random unitary channel and amplitude damping channel we obtain non-Markovian conditions at maximally coherent state of system.
In the language of quantum information theory we study the entropy squeezing of a two-level atom in a Kerr-like medium. A definition of squeezing is presented for this system, based on information theory. The utility of the definition is illustrated by examining the entropy squeezing of a two-level atom with a Kerr-like medium. The influence of the non-linear interaction of the Kerr medium, the atomic coherence and the detuning parameter on the properties of the entropy and squeezing of the atomic variables is examined.
Abstract As an important resource, quantum coherence is one of the fundamental features of the quantum world. It is essential to understand the relationship between the resource and the mixedness of an open quantum system. We present complementary relations between the l p ( 1 ⩽ p < 2 ) norm of coherence and the normalized linear entropy mixedness. We then study the geometry of the complementary relations for Bell-diagonal states, as well as the evolutions of Werner and isotropic states under bit flip, phase flip, bit-phase flip, depolarizing, generalized amplitude damping and amplitude damping channels. Our results include some existing conclusions as special cases.