共查询到20条相似文献，搜索用时 15 毫秒
1.
We theoretically study the non-Markovian disentanglement dynamics of a two-qubit system coupled to nonequilibrium environments with nonstationary and non-Markovian random telegraph noise statistical properties. The reduced density matrix of the two-qubit system can be expressed as the Kraus representation in terms of the tensor products of the single qubit Kraus operators. We derive the relation between the entanglement and nonlocality of the two-qubit system which are both closely associated with the decoherence function. We identify the threshold values of the decoherence function to ensure the existences of the concurrence and nonlocal quantum correlations for an arbitrary evolution time when the two-qubit system is initially prepared in the composite Bell states and the Werner states, respectively. It is shown that the environmental nonequilibrium feature can suppress the disentanglement dynamics and reduce the entanglement revivals in non-Markovian dynamics regime. In addition, the environmental nonequilibrium feature can enhance the nonlocality of the two-qubit system. Moreover, the entanglement sudden death and rebirth phenomena and the transition between quantum and classical nonlocalities closely depend on the parameters of the initial states and the environmental parameters in nonequilibrium environments. 相似文献
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量子物理是当代科学发展的基石,多次引发高技术革命.它与信息科学结合,产生了交叉学科——量子信息,为突破计算机芯片的尺度极限提供了全新的解决思路.自1987年起,文章作者及其合作者对量子开系统理论、量子退相干及其相关的量子物理基本问题进行了系统的探索,契合了最近10年量子信息研究的快速发展.文章首先结合上世纪70年代末彭桓武先生关于量子开系统(阻尼谐振子的量子化)的重要研究工作,介绍了量子开系统的基本概念及其研究的科学意义,同时简略介绍了文章作者及其合作者在量子开系统理论及其在量子信息应用方面的系列研究工作. 相似文献
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量子物理是当代科学发展的基石,多次引发高技术革命.它与信息科学结合, 产生了交叉学科——量子信息,为突破计算机芯片的尺度极限提供了全新的解决思路.自1987年起,文章作者及其合作者对量子开系统理论、量子退相干及其相关的量子物理基本问题进行了系统的探索,契合了最近10年量子信息研究的快速发展.文章首先结合上世纪70年代末彭桓武先生关于量子开系统（阻尼谐振子的量子化）的重要研究工作, 介绍了量子开系统的基本概念及其研究的科学意义,同时简略介绍了文章作者及其合作者在量子开系统理论及其在量子信息应用方面的系列研究工作. 相似文献
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The influence of decoherence on interference between twotrapped Bose-Einstein condensates with arbitrary initial states isstudied. Analytic expressions of the intensity and visibility ofthe interference pattern are found. It is shown that thedecoherence weakens the interference intensity and decreases thevisibility of the interference pattern. 相似文献
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Finding the most robust entangled states during the whole process of decoherence is a particularly fundamental problem for quantum physics and quantum information processing. In this paper, the decoherence process of two-qubit system under two individual identical decoherence channels is investigated systematically. We find that although the robustness of two-qubit states with same initial entanglement is usually different, the Bell-like states are always the most robust entangled states during decoherence. That is to say, affected by the same amount of noise, the remain entanglement of an arbitrary two-qubit state is not more than that of a Bell-like state with the same initial entanglement. 相似文献
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The weak objectification and Bell/CHSH inequalities are studied for a particular type of set of states of two spin-1/2 particles.
The restriction on interference term which allows Bell/CHSH inequalities to be satisfied are found out. 相似文献
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Bar&#x; akmak
zgür E. Müstecapl&#x;olu Mauro Paternostro Bassano Vacchini Steve Campbell 《Entropy (Basel, Switzerland)》2021,23(8)
We investigate the implications of quantum Darwinism in a composite quantum system with interacting constituents exhibiting a decoherence-free subspace. We consider a two-qubit system coupled to an N-qubit environment via a dephasing interaction. For excitation preserving interactions between the system qubits, an analytical expression for the dynamics is obtained. It demonstrates that part of the system Hilbert space redundantly proliferates its information to the environment, while the remaining subspace is decoupled and preserves clear non-classical signatures. For measurements performed on the system, we establish that a non-zero quantum discord is shared between the composite system and the environment, thus violating the conditions of strong Darwinism. However, due to the asymmetry of quantum discord, the information shared with the environment is completely classical for measurements performed on the environment. Our results imply a dichotomy between objectivity and classicality that emerges when considering composite systems. 相似文献
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We discuss the possibility of making the initial definitions of mutually different (possibly interacting, or even entangled) systems in the context of decoherence theory. We point out relativity of the concept of elementary physical system as well as point out complementarity of the different possible divisions of a composite system into “subsystems,” thus eventually sharpening the issue of “what is system.” 相似文献
9.
The influence of non‐Markovian characters on the adiabatic evolution is investigated. The adiabatic Raman process is simulated in a three‐level system coupled to two independent environments. The results show that the memory effect of environments can restrain the decoherence effect of the system. Even if the system has strong decay rates in the non‐Markovian environments, the adiabatic population transfer can be still completed efficiently. Moreover, the memory effect can reduce the dependence of the adiabatic evolution on the Rabi frequency. Specifically, the two independent non‐Markovian baths can suppress the decoherence more effectively than a single non‐Markovian bath. 相似文献
10.
Quantum Fisher information (QFI) has potential applications in quantum metrology tasks. QFI is investigated when the consecutive actions of a quantum channel on the sequence of qubits have partial classical correlations. The results showed that while the decoherence effect is detrimental to QFI, effects of such classical correlations on QFI are channel-dependent. For the Bell-type probe states, the classical correlations on consecutive actions of the depolarizing and phase flip channels can be harnessed to improve QFI, while the classical correlations in the bit flip and bit-phase flip channels induce a slight decrease of QFI. For a more general parameterization form of the probe states, the advantage of using the initial correlated system on improving QFI can also remain in a wide regime of the correlated quantum channels. 相似文献
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We study the dynamics of two-level atomic systems(qubits) subject to a double-layer environment that consists of a network of single-mode cavities coupled to a common reservoir. A general exact master equation for the dynamics of a qubit system can be obtained by the quantum-state-diffusion(QSD) approach, which is extended to our spin-cavity-boson model. The quantumness of the atoms comprising coherence and entanglement is investigated for various configurations of the double-layer environment.The findings indicate that parametric control is available for the preservation and generation of system-quantumness by regulating the cavity network. Moreover the underlying physics is profoundly revealed by an effective model obtained by a unitary transformation. Therefore, our work provides an interesting proposal to protect the quantumness of open systems in the framework of a double-layer environment containing bosonic modes. 相似文献
13.
量子信息技术主要基于量子纠缠,量子纠缠源作为重要的相干叠加态,其相干性很容易受到环境的影响而变得非常脆弱,甚至导致量子信息处理的失败.因此,全面揭示不同噪声环境和不同噪声信道下量子纠缠源演化规律,进而探寻抑制退相干的方法就显得至关重要.本文以量子信息最基本的单元-两比特纠缠对作为研究对象,实验上利用线性光学系统模拟了比特翻转和相移噪声(集体和非集体),研究了纠缠源在不同噪声环境及单、双和混合噪声信道下保真度的变化规律.实验结果表明:对同一种噪声类型,当纠缠比特经过双通道噪声环境时,其纠缠特性破坏得快;当纠缠比特经过非集体环境时,其纠缠特性消失得快.对不同噪声类型比较,结果表明比特翻转噪声相对于相移噪声更容易破坏纠缠特性.所得结论对纠缠退相干的理论和实验研究具有重要的借鉴意义,同时对基于非线性光学系统的量子信息处理技术具有重要的应用价值. 相似文献
14.
We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment,the tunneling element,the initial state of the environment,and the system-environment coupling strength.From the analysis,we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it. 相似文献
15.
The dynamics of two coupled spins-1/2 coupled to a spin-bath isstudied as an extended model of the Tessieri--Wilkie Hamiltonian. Thepair of spins served as an open subsystem is prepared in one of theBell states and the bath consisting of some spins-1/2 is in a thermalequilibrium state from the very beginning. It is found that withincreasing coupling strength of the bath spins, the bath forms aresonant antiferromagnetic order. The polarization correlationbetween the two spins of the subsystem and the concurrence of it arerecovered to some extent in the isolated subsystem. This suppressionof the subsystem decoherence may be used to control the quantumdevices in practical applications. 相似文献
16.
Ali H. Abdollahi Bafghi Mahtab Mirmohseni Masoumeh Nasiri-Kenari 《Entropy (Basel, Switzerland)》2022,24(8)
In this paper, we study the degrees of freedom (DoF) of a frequency-selective K-user interference channel in the presence of an instantaneous relay (IR) with multiple receiving and transmitting antennas. We investigate two scenarios based on the IR antennas’ cooperation ability. First, we assume that the IR receiving and transmitting antennas can coordinate with each other and that the transmitted signal of each transmitting antenna can depend on the received signals of all receiving antennas, and we derive lower and upper bounds for the sum DoF of this model. In an interference alignment scheme, we divide receivers into two groups called clean and dirty receivers. We design our scheme such that a part of the messages of clean receivers can be de-multiplexed at the IR. Thus, the IR can use these message streams for an interference cancellation at the clean receivers. Next, we consider an IR, the antennas of which do not have coordination with each other and where the transmitted signal of each transmitting antenna depends only on the received signal of its corresponding receiving antenna. We also derive lower and upper bounds for the sum DoF for this model of IR. We show that the achievable sum DoF decreases considerably compared with the coordinated case. In both of these models, our schemes achieve the maximum K sum DoF if the number of transmitting and receiving antennas is more than a finite threshold. 相似文献
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Understanding the physical significance and probing the global invariants characterizing quantum topological phases in extended systems is a main challenge in modern physics with major impact in different areas of science. Here, a quantum‐information‐inspired probing method is proposed where topological phase transitions are revealed by a non‐Markovianity quantifier. The idea is illustrated by considering the decoherence dynamics of an external read‐out qubit that probes a Su–Schrieffer–Heeger (SSH) chain with either pure dephasing or dissipative coupling. Qubit decoherence features and non‐Markovianity measure clearly signal the topological phase transition of the SSH chain. 相似文献
20.
王中结 《原子与分子物理学报》2006,23(4):757-761
对单个囚禁离子在热库作用下的退相干的控制问题进行了研究.本文提出的控制方法是基于消除自由哈密顿技术和脉冲重聚技术的结合.前者是利用一个经典大失谐激光场作用于囚禁离子来实现的,而后者是利用一系列的激光π脉冲来实现的.解析与数值表明,应用这种控制方法可以有效消除量子退相干且比纯粹应用脉冲重聚技术要好. 相似文献