We quantify the total, quantum, and classical correlations with entropic measures, and quantitatively compare these correlations in a quantum system, as exemplified by a Heisenberg dimer which is subjected to the change of environmental parameters: temperature and nonuniform external field. Our results show that the quantum correlation may exceed the classical correlation at some nonzero temperatures, though the former is rather fragile than the later under thermal fluctuation. The effect of the external field to the classical correlation is quite different from the quantum correlation.
Quantum correlations of identical particles subject to classical environmental noise
本文基于[H. M. Wiseman等人，菲丝Rev. Lett 91，097902（2003）]。这种粒子的不和谐然后被用来评估两个相同的玻色子（费米子）系统中的量子相关性，其中粒子在一维晶格中执行哈伯德哈密顿量描述的量子随机行走。粒子的动力学要么不受干扰，要么受到经典环境噪声的影响-例如随机电报，粉红色或棕色噪声。观察到的结果是一致的粒子的纠缠，我们观察到，粒子之间的现场相互作用有一个重要的保护作用的关联对系统的退相干。
We show theoretically how a correlation of multiple measurements on a qubit undergoing pure dephasing can be expressed as environmental noise filtering. The measurement of such correlations can be used for environmental noise spectroscopy, and the family of noise filters achievable in such a setting is broader than the one achievable with a standard approach, in which dynamical decoupling sequences are used. We illustrate the advantages of this approach by considering the case of noise spectrum with sharp features at very low frequencies. We also show how appropriately chosen correlations of a…
A master equation has been constructed for a global system-bath interaction both in the absence as well as presence of non-Markovian noise. For the memoryless case, it has been exactly solved for a paradigmatic class of two qubit states in high and zero temperature thermal environment. For the non-Markovian model, it has been solved for zero temperature bath. The evolution of quantum coherence and entanglement has been observed in presence of the above mentioned interactions. We show that the global part of the system-bath interaction compensates for the decoherence, resulting in slow down of …
Quantum-to-classical transition is a fundamental open question in physics frontier. Quantum decoherence theory points out that the inevitable interaction with environment is a sink carrying away quantum coherence, which is responsible for the suppression of quantum superposition in open quantum system. Recently, quantum Darwinism theory further extends the role of environment, serving as communication channel, to explain the classical objectivity emerging in quantum measurement process. Here, we used a six-photon quantum simulator to investigate classical and quantum information proliferation …
We study intraenvironmental classical and quantum correlations in a thermal machine, which is modeled as a driven quantum system coupled with thermal reservoirs. We compute the mutual information, the quantum discord, and the entanglement between two parts of the environment formed by oscillators centered around two different frequencies. We show that there are only two processes that generate time-extensive correlations in the long-time limit. First, there is a resonant process which is responsible for the transport of excitations between different environmental modes due to the absorption (o…
Environmental interactions are ubiquitous in practical instances of any quantum information processing protocol. The interaction results in depletion of various quantum resources and even complete loss in numerous situations. Nonlocality, which is one particular quantum resource marking a significant departure of quantum mechanics from classical mechanics, meets the same fate. In the present work we study the decay in nonlocality to the extent of the output state admitting a local hidden state model. Using some fundamental quantum channels we also demonstrate the complete decay in the resource…
An assessment is given as to the extent to which pure unitary evolution, as distinct from environmental decohering interaction, can provide the transition necessary for an observer to interpret perceived quantum dynamics as classical. This has implications for the interpretation of quantum wavefunctions as a characteristic of ensembles or of single particles and the related question of wavefunction collapse.
We propose a method for characterising the energy level structure of a solid-state qubit by monitoring the noise level in its environment. We consider a model persistent-current qubit in a lossy resevoir and demonstrate that the noise in a classical bias field is a sensitive function of the applied field.
An ETH-ansatz-motivated environmental-branch approach to open quantum systems
University of Science and Technology of China（中国科学技术大学）；CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China（中国科学技术大学微尺度磁共振重点实验室）；Anhui Center for fundamental sciences in theoretical physics（安徽基础科学中心理论物理）
Environmental records unlock universal quantum computation from thermal decoherence
HK Institute of Quantum Science & Technology, The University of Hong Kong（香港量子科学研究所，香港大学）；QICI Quantum Information and Computation Initiative, School of Computing and Data Science, The University of Hong Kong（QICI量子信息与计算倡议，计算与数据科学学院，香港大学）
Quantum states of gravitational source masses can lead to experimental outcomes that are inconsistent with the predictions of a purely classical field theory of gravity. Environmental decoherence places strict boundary conditions to the potential realization of such experiments: sufficiently mild not to act as a fundamental show-stopper, yet sufficiently demanding to represent a formidable challenge to the next generation of quantum experiment(er)s.
Total Ordering of Resources: A Quantum-Classical Separation
Institute of Fundamental Technological Research, Polish Academy of Sciences（波兰科学院基础技术研究所在）；Departamento de Matemáticas, Universidad Carlos III de Madrid（马德里卡洛斯三世大学数学系）；Instituto de Ciencias Matemáticas (ICMAT)（马德里高等数学研究所）
We present measurements of the dynamics of a polarized magnetic environment coupled to the flux degree of freedom of rf-SQUID flux qubits. The qubits are used as both sources of polarizing field and detectors of the environmental polarization. We probe dynamics at timescales from 5 $μ$s to 5 ms and at temperatures between 12.5 and 22 mK. The measured polarization versus temperature provides strong evidence for a phase transition at a temperature of $5.7\pm 0.3$ mK. Furthermore, the environmental polarization grows initially as $\sqrt{t}$, consistent with spin diffusion dynamics. However, spin …
In classical mechanics, a natural way to simplify a many-body problem is to ``replace'' some of the elements of the composite system with surrogate \textit{force fields}. In the realm of quantum mechanics, however, such a description is rarely compatible with the formalism of the theory. Nevertheless, the quantum version of external field models---the so-called \textit{noise representations}---can be employed in certain circumstances. The mathematics behind these models indicate that the appearing fields typically exhibit random fluctuations, hence, the name \textit{noise field} is more apt. I…
