共查询到20条相似文献,搜索用时 46 毫秒
1.
Using the pseudomode method, we theoretically analyze the creation of quantum correlations between two two-level dipole-dipole interacting atoms coupled with a common structured reservoir with different coupling strengths. Considering certain classes of initial separable-mixed states, we demonstrate that the sudden birth of atomic entanglement as well as the generation of stationary quantum correlations occur. Our results also suggest a possible way to control the occurrence time of entanglement sudden birth and the stationary value of quantum correlations by modifying the initial conditions of states, the dipole-dipole interaction, and the relative coupling strength. These results are helpful for the experimental engineering of entanglement and quantum correlations. 相似文献
2.
Based on an open exactly solvable system coupled to an environment with nontrivial spectral density, we connect the features of quantum and classical correlations with some features of the environment, initial states of the system, and the presence of initial system–environment correlations. Some interesting features not revealed before are observed by changing the structure of environment, the initial states of system, and the presence of initial system–environment correlations. The main results are as follows. (1) Quantum correlations exhibit temporary freezing and permanent freezing even at high temperature of the environment, for which the necessary and sufficient conditions are given by three propositions. (2) Quantum correlations display a transition from temporary freezing to permanent freezing by changing the structure of environment. (3) Quantum correlations can be enhanced all the time, for which the condition is put forward. (4) The one-to-one dependency relationship between all kinds of dynamic behaviors of quantum correlations and the initial states of the system as well as environment structure is established. (5) In the presence of initial system–environment correlations, quantum correlations under local environment exhibit temporary multi-freezing phenomenon. While under global environment they oscillate, revive, and damp, an explanation for which is given. 相似文献
3.
Huang Xiao-Li Shao-Cheng Hou Lin-Cheng Wang Xue-Xi Yi 《Central European Journal of Physics》2012,10(4):947-952
Taking a two-level system interacting with a two-band environment as an example, we discuss the non-Markovianity and initial system-environment correlations for the generalized Lindblad master equation by using a recently introduced measure given by Breuer et al. Our results show that the initial states of the environment and initial system-environment correlations have strong effects on the non-Markovianity of the reduced system. Moreover, we also show that information and energy can flow in different directions, i.e., energy flows to the system while information flows from the system, which is quite different from previous results. 相似文献
4.
Aguilar GH Farías OJ Maziero J Serra RM Ribeiro PH Walborn SP 《Physical review letters》2012,108(6):063601
The perception that quantum correlations can still appear in separable states has opened exciting new possibilities regarding their use as a resource in quantum information science. Quantifying such quantum correlations involves the complete knowledge of the system's state and numerical optimization procedures. Thus, it is natural to seek methods involving fewer measurements that indicate the nature of the correlations in a system. Here we propose a classicality witness that can be accurately estimated via statistics from a single measurement and perform an experiment to explore the utility of this witness for quantum states with different types of correlations. 相似文献
5.
We introduce a method that allows the disclosure of correlations between particle positions in an arbitrary many‐body system. The method is based on a well‐known simulated annealing algorithm and the proposed artificial distribution technique. Additionally, we investigate correlations in quantum Hall liquids (we consider many‐body wave functions that have been recently determined via the cyclotron subgroup model) and present three‐dimensional plots of configuration probability distributions that have been established from numerical simulations. We demonstrate that the preferred simultaneous positions of particles (configurations of positions, which correspond to large values of a system's probability distribution, ) tend to form complicated geometric structures, which are equivalent to classical Wigner crystals only for Laughlin states. Furthermore, we claim that quantum Hall liquids attributed to non‐Laughlin fillings are correlated on subdomains rather than on a whole particle domain (due to a quantizing magnetic field, which modifies the topology of a system's dynamics). Finally, we characterize Hall‐like internal orders in terms of statistical correlations (one‐dimensional unitary representations of cyclotron subgroups). Our conclusions concerning the stability of many‐body states agree with transport measurements and various numerical studies. 相似文献
6.
通过综合模式搜索法、广义Lagrange乘子法、以及转轴法等多种数值方法, 建立了一套针对多轨道Hubbard模型隶玻色子解法的数值优化方法. 该数值方法能够在考虑晶场劈裂、轨道间跳跃以及真实能带结构基础上, 利用隶玻色子方法计算实际关联电子材料的性质. 首先利用该方法计算了两轨道体系的Mott金属-绝缘体转变性质, 得到了与目前已有工作一致的结果; 然后利用该方法讨论了Coulomb关联对三轨道体系NaxCoO2的影响. 结果表明: 在中间关联情况下由eg'轨道形成的六个小Fermi面消失, 原因是由于电子关联导致该轨道上的空穴数随U减少. 这些结果也证实了算法的正确性和有效性.
关键词:
多轨道Hubbard模型
隶玻色子
Mott转变
xCoO2')" href="#">NaxCoO2 相似文献
7.
Vlatko Vedral 《Foundations of Physics》2010,40(8):1141-1154
We discuss two qualities of quantum systems: various correlations existing between their subsystems and the distinguishability
of different quantum states. This is then applied to analysing quantum information processing. While quantum correlations,
or entanglement, are clearly of paramount importance for efficient pure state manipulations, mixed states present a much richer
arena and reveal a more subtle interplay between correlations and distinguishability. The current work explores a number of
issues related with identifying the important ingredients needed for quantum information processing. We discuss the Deutsch-Jozsa
algorithm, the Shor algorithm, the Grover algorithm and the power of a single qubit class of algorithms. In the latter, a
quantity called discord is seen to be more important than entanglement. One section is dedicated to cluster states where entanglement
is crucial, but its precise role is highly counter-intuitive. Here we see that the notion of distinguishability becomes a
more useful concept. 相似文献
8.
Dagomir Kaszlikowski Marek Żukowski 《International Journal of Theoretical Physics》2003,42(5):1023-1035
We present a brief historical introduction to the topic of Bell's theorem. Next we present the surprising features of the three-particle Greenberger—Horne—Zeilinger (GHZ) states. Finally we shall present a method of analysis of the GHZ correlations, which is based on a numerical approach, which is effectively equivalent to the full set of Bell inequalities for correlation functions for the given problem. The aim of our numerical approach is to answer the following question: Do additional possible local settings lead for the GHZ states to more pronounced violation of local realism (measured by the resistance of the quantum nature of the correlations with respect to “white” noise admixtures)? 相似文献
9.
Tracing back to the initial state of a time-evolutionary process using a segment of historical time series may lead to many meaningful applications. In this paper, we present an estimation method that can detect the initial conditions, unobserved time-varying states and parameters of a dynamical (chaotic) system using a short scalar time series that may be contaminated by noise. The technique based on the Newton-Raphson method and the least-squares algorithm is tolerant to large mismatch between the initial guess and actual values. The feasibility and robustness of this method are illustrated via the numerical examples based on the Lorenz system and Rossler system corrupted with Gaussian noise. 相似文献
10.
Wen-Jian Yu Yong-Bo Wei Hai Li Lin Li Jian Zou Bin Shao 《International Journal of Theoretical Physics》2016,55(11):4785-4797
We investigate the quantum speed limit (QSL) time of an electronic spin coupled to a bath of nuclear spins. We consider three types of initial states with different correlations between the system and bath, i.e., quantum correlation, classical correlation, and no any correlation. Interestingly, we show that the QSL times of the central spin for these three types of initial correlations are identical when the couplings are homogeneous. However, it is remarkable different for inhomogenous couplings. The QSL time of the central spin is sensitive to the initial states, the average coupling strength, the distribution of the couplings between the system and bath and the number of the nuclear spins in the bath. Furthermore, we find that the coherence in the initial state has significant influences on the QSL time of the system, and can lead to the increase of QSL time for homogeneous couplings. 相似文献
11.
Ram Narayan Deb 《Brazilian Journal of Physics》2017,47(2):107-121
We propose a total measure of multi-particle quantum correlation in a system of N two-level atoms (N qubits). We construct a parameter that encompasses all possible quantum correlations among N two-level atoms in arbitrary symmetric pure states and define its numerical value to be the total measure of the net atom-atom correlations. We use that parameter to quantify the total quantum correlations in atomic Schrödinger cat states, which are generated by the dispersive interaction in a cavity. We study the variation of the net amount of quantum correlation as we vary the number of atoms from N=2 to N=100 and obtain some interesting results. We also study the variation of the net correlation, for fixed interaction time, as we increase the number of atoms in the excited state of the initial system, and notice some interesting features. We also observe the behaviour of the net quantum correlation as we continuously increase the interaction time, for the general state of N two-level atoms in a dispersive cavity. 相似文献
12.
Doubly-excited states of the isoelectronic sequence of H−, in which both electrons are in high principal quantum numbers, are examined on the basis of alternative pictures of the
correlations between the two electrons. Restricting ourselves to the lowest1
S states with both electrons in principal quantum numbern, we parametrise the electron-electron interaction on the basis of these pictures and compare the resulting simple expressions
with more elaborate numerical calculations. This provides further understanding of the nature of correlations in such states.
1984 JILA Visiting Fellow. 相似文献
13.
In this paper, the output quantum correlations of three fields interacting with inverted Y-type atoms inside a three-mode cavity are investigated. By numerically calculating the stationary noise spectra of the fields, we show that it is possible to generate the genuine tripartite continuous variable entanglement outside the cavity by coherently preparing the atoms in a superposition of the upper excited state and two ground states initially. Our numerical results demonstrate that both zero frequency entanglement and sideband frequency entanglement can be obtained under different initial coherent conditions. In addition, we investigate the thermal fluctuation effects on the quantum entanglement. It is found out that the entanglement occurring in a high frequency regime is more robust against thermal noise than the zero frequency entanglement, which may be useful for quantum communication. 相似文献
14.
15.
Dynamics of measurement-induced non-locality and geometric discord with initial system-environment correlations 下载免费PDF全文
We analyze the dynamics of geometric measure of discord (GMOD) and measurement-induced non-locality (MIN) in the presence of initial system-reservoir correlations without Born and Markov approximation. Although the initial system-environment states have the same reduced density matrices for both the system and environment, the effects of different initial system-environment correlations have been shown to fundamentally alter the time evolution of GMOD and MIN between two quantum systems in both Markovian and non-Markovian regimes. In general, both GMOD and MIN experience a sudden increase for initially quantum-correlated states, and a sudden decrease for classical-correlated states before they reach the same stationary values with initially factorized states. 相似文献
16.
17.
虚拟流体方法中界面处Riemann问题定义方式的改进 总被引:1,自引:1,他引:0
对RGFM中定义Riemann问题的方式进行改进,取距离界面适当远处的插值点处的状态作为Riemann问题的初值.并用数值算例对改进前后的RGFM进行比较. 相似文献
18.
We study dynamics of nonclassical correlations by exactly solving a model consisting of two atomic qubits with spontaneous emission. We find that the nonclassical correlations defined by different measures give different qualitative characterizations of those correlations. The relative behaviors of those correlation measures are presented explicitly for various quantum states in the two-qubit atomic system. In particular, we find that the robustness of quantum correlations can be greatly enhanced by performing appropriate local unitary operations on the initial state of the system. 相似文献
19.
A.-S. F. Obada F. A. Mohammed H. A. Hessian A.-B. A. Mohamed 《International Journal of Theoretical Physics》2007,46(4):1027-1044
In this paper, we study the time evolution of the entropies and the degree of entanglement in the mixed state for a multi-quanta
JC model taking into consideration Stark shift and Kerr-like medium effect, we use a numerical method to investigate the time
evolution of the partial entropy of the atom and field subsystem. This is done in the framework of the multi-quanta presses
JC model with both the Stark shift and Kerr-like medium effect added. Furthermore, we examine the effect of the superposition
states and a statistical mixture of coherent states as an initial field on the entropies and entanglement. Our results show
that the setting of the initial state play an important role in the evolution of the sub-entropies and entanglement. 相似文献
20.
The currently used ghost-image schemes traditionally involve two-mode entangled light states or incoherent radiation. Here, we consider the application of four-mode entangled light states and show that multiplexed ghost images (MGI) formed by four-mode entangled quantum light states have mutual spatial correlations determined by the eighth-order field correlation functions. We develop a special algorithm to calculate high-order correlations of Bose operators. We also demonstrate that accounting of the MGI correlations allows us to improve the quality of the restored image of an object while processing the MGI by the measurement reduction method. We carry out computer modeling of the image recovery from the MGI. We establish that in the considered example the signal-to-noise ratio of the reduced ghost image is 4.6 times higher than the best signal-to-noise ratio for the ghost images themselves. 相似文献