共查询到20条相似文献,搜索用时 31 毫秒
1.
Song-Song Li 《International Journal of Theoretical Physics》2017,56(10):3061-3067
We investigate spin squeezing and entanglement of the two-axis twisting model with the bosonization method, The smaller linear interaction can produce a stronger spin squeezing, the better entanglement and the squeezing and entanglement can maintain a longer time interval. The stronger spin squeezing and the better entanglement can also be achieved by increasing the number of particles. 相似文献
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Quantum entanglement between two field modes can be achieved through the collective squeezing of the two respective modes. If single-mode squeezing is performed prior to such a two-mode squeezing, an enhancement of entanglement production can happen. Interestingly, the occurrence of this enhancement can be implicitly linked to the local classical dynamical behavior via the paradigm of quantum–classical correspondence. In particular, the entanglement generated through quantum chaos is found to be hardly enhanced by prior squeezing, since it is bounded by the saturation value of the maximally entangled Schmidt state with fixed energy. These results illustrate that entanglement enhancement via initial squeezing can serve as a useful indicator of quantum chaotic behaviour. 相似文献
4.
Quantum entanglement and nonlocality properties of a family of
two-mode Gaussian pure states have been investigated. The results
show that the entanglement of these states is determined by both the
two-mode squeezing parameter and the difference of the two
single-mode squeezing parameters. For the same two-mode squeezing
parameter, these states show larger entanglement than the usual
two-mode squeezed vacuum state. The violation of Bell inequality
depends strongly on all the squeezing parameters of these states and
disappears completely in the limit of large squeezing. In
particular, these states can exhibit much stronger violation of
local realism than two-mode squeezed vacuum state in the range of
experimentally available squeezing values. 相似文献
5.
Single-atom entropy squeezing and quantum entanglement in Tavis--Cummings model with atomic motion 下载免费PDF全文
We examine the single-atom entropy squeezing and the atom-field entanglement in a system of two moving twolevel atoms interacting with a single-mode coherent field in a lossless resonant cavity.Our numerical calculations indicate that the squeezing period,the squeezing time and the maximal squeezing can be controlled by appropriately choosing the atomic motion and the field-mode structure.The atomic motion leads to a periodical time evolution of entanglement between the two-atom and the field.Moreover,there exists corresponding relation between the time evolution properties of the atomic entropy squeezing and that of the entanglement between the two atoms and the field. 相似文献
6.
We study the effect of a thermal reservoir on the squeezing transfer and entanglement between two identical harmonic oscillators, caused by a bilinear coupling of the RWA type. We analyze the evolution of the invariant squeezing coefficients of each mode for arbitrary initially factorized mixed states, as well as the separability coefficient based on Simon's criterion for Gaussian states. We show the importance of initial squeezing for the emergence of entanglement and the existence of critical temperatures above which no squeezing transfer or entanglement are possible. 相似文献
7.
对于几类常见的量子态, 对自旋压缩和量子Fisher信息进行了比较研究.得到量子Fisher信息的表达式,以Fisher信息为基础,给出了量子纠缠的判据,结果表明:比较于自旋压缩,该判据有明显的优势.(1).对于两个Qubit的对称态,该判据与自旋压缩,concurrence完全等价;(2).对于两个Qubit的非对称态的纠缠,自旋压缩不能检验其纠缠,但对于部分态,该判据也能检验;(3).对于Dicke态, 自旋压缩不能检验其纠缠,但该判据能检验且完全等价于concurrence. 相似文献
8.
GHZ类态原子体系与相干态光场相互作用的光场压缩特性 总被引:1,自引:1,他引:0
本文采用求解Schr dinger方程和数值计算的方法,研究了处于GHZ类态的三个全同二能级纠缠原子与相干态光场相互作用的光场压缩特性,结果表明:光场压缩量随时间的演化关系与三原子体系纠缠度和相干态光场的光场强度相关.在光场较弱、纠缠度较小时,可出现光场压缩现象;光场的增强或纠缠度的增加,都会使光场压缩现象消失. 相似文献
9.
对于几类常见的量子态, 对自旋压缩和量子Fisher信息进行了比较研究.得到量子Fisher信息的表达式,以Fisher信息为基础,给出了量子纠缠的判据,结果表明:比较于自旋压缩,该判据有明显的优势.(1).对于两个Qubit的对称态,该判据与自旋压缩,concurrence完全等价;(2).对于两个Qubit的非对称态的纠缠,自旋压缩不能检验其纠缠,但对于部分态,该判据也能检验;(3).对于Dicke态, 自旋压缩不能检验其纠缠,但该判据能检验且完全等价于concurrence. 相似文献
10.
Dao-Ming Lu 《International Journal of Theoretical Physics》2018,57(9):2767-2774
Superposition of photon subtraction two times and photon addition two times excited two modes squeezing vacuum state (SPSAESVT) is introduced, which is generated by operation of superposition of annihilation operator and creation operator on two modes squeezed vacuum state. Non-classical properties of SPSAESVT, such as squeezing effect, anti-bunching effect, the violation of Cauchy-Schwartze inequality and the entanglement property between two modes, are investigated. Using numerical methods, the influences of the superposition coefficient of operators and that of squeezing parameter on its non-classical properties are discussed. The results show that SPSAESVT does not display antibunching effect, but it displays squeezing effect, and there are the violation of Cauchy-Schwartze inequality and the entanglement between two modes. Further, its squeezing effect is not affected by the superposition coefficient of the operators, but there is a nonlinear relationship both between the violation of Cauchy-Schwartze inequality and the superposition coefficient, and between the entanglement property and the superposition coefficient. As squeezing parameter increases, its squeezing effect and entanglement property are strengthened, but the violation of Cauchy-Schwartze inequality is weakened. 相似文献
11.
We investigate the fundamental connection between quadrature squeezing and continuous variable entanglement within a general
class of two-coupled oscillator systems. We determine the quantitative relationship between them through the squeezing parameter
and the entanglement entropy of the lowest energy eigenstate of the coupled oscillator systems numerically. Unlike the relation
between entanglement and uncertainty product, we found that this relationship is, by no means, the same for the whole class
of coupled oscillator systems: to a large extent it depends on the order and strength of the anharmonic potential, which implies
that knowledge of the anharmonic potential of the coupled oscillator system is required before one can characterize the degree
of entanglement through the squeezing parameter. Our results reveal that a more effective approach to enhance squeezing is
to adjust the anharmonicity of the system potential, instead of increasing the quantum correlations between the oscillators.
In addition, by probing into a quantum catastrophe model, we uncover transitions in the entanglement entropy and squeezing
relation as the potential changes from a single well to a triple well, and then a double-well structure. The transitions appear
through distinct entropy–squeezing relation, with a multi-well structure displaying a larger change in the antisqueezing behavior
of the position quadrature than the single-well structure, for the same change in the entanglement entropy. 相似文献
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研究了三量子位和四量子位Heisenberg XY链中的基态纠缠与自旋压缩,给出了纠缠C和自旋压缩参数ξ2的解析表达式.结果表明,当外部磁场B大于某一临界值Bc时,纠缠与自旋压缩等价,即纠缠意味着自旋压缩,反之亦然.对三量子位情形,Bc=J[(4-3γ2)1/2-1];对四量子位情形,Bc可以通过数值方法进行求解. 相似文献
14.
Cui-Xia Wang Xiong Ding Guo-Qiang Huang Cui-Lan Luo 《International Journal of Theoretical Physics》2016,55(6):2931-2935
We investigate quantum entanglement in a generic-spin model with spin squeezing criterions based on squeezing inequalities. By analytically and numerically calculating the squeezing criterions, we show that the system is always entangled except at some special times and the stronger entanglement may be achieved by decreasing the coupling strength and increasing the number of particles. 相似文献
15.
J.L. Ding 《Optics Communications》2011,284(12):2949-2954
The interaction of a collection of N four-level tripod configuration atoms with two orthogonally polarized probe fields is investigated. Under the condition of electromagnetically induced transparency (EIT), we calculate the squeezing and entanglement spectra of the output probe fields. By analyzing the output spectrum, we find that the squeezing and entanglement of the probe fields can be well-preserved after passing through the optically thick medium. Additionally, the effects of the ground state dephasing rates of the atoms on the entanglement and squeezing of the output two-mode squeezed fields are investigated. It is shown that the dephasing rates will degrade the entanglement and squeezing, and these quantum properties can be lost when the dephasing rates increase up to a certain value. This will be useful in the quantum computation and quantum communication. 相似文献
16.
We investigate the entropy squeezing and entanglement of the Cooper-pair box interacting with multi-photon cavity field. The field is prepared initially in the coherent state, while the Cooper-pair box is assumed to start from a mixed state. We find that the number of photons and the detuning parameters play an important role in the entropy squeezing and entanglement. We observe that the entropy squeezing can be used as a good indicator of the entanglement. This study opens promising perspectives for creating remote quantum information processing networks. 相似文献
17.
Duc Minh Truong Hoai Thi Xuan Nguyen An Ba Nguyen 《International Journal of Theoretical Physics》2014,53(3):899-910
In this paper, we study some higher-order nonclassical properties and intermodal entanglement that may arise in the so called two-mode photon-added displaced squeezed state. We derive analytical expressions for the degree of sum squeezing and difference squeezing, which are interesting kinds of two-mode squeezing, as well as for the degree of antibunching to any orders. We also examine the degree of entanglement between the two modes using the existing Hillery-Zubairy criterion. Based on the derived expressions we analyze in detail the behavior of these nonclassical effects and entanglement depending on the parameters involved. 相似文献
18.
用Von Neumann熵研究了附加克尔介质的压缩真空场与二能级原子依赖强度耦合相互作用量子体系的量子纠缠特性.讨论了初始压缩真空场的压缩度以及克尔非线性作用的强度对该量子体系纠缠特性的影响.结果表明,克尔介质的非线性作用的强弱可以改变体系量子纠缠的周期性;在初始压缩度较大(r=5)时,克尔介质的非线性作用可导致原子与场持续地处于最大纠缠态,无消纠缠态或持续地处于消纠缠态.
关键词:
压缩真空态
克尔介质
依赖强度耦合J-C模型
Von Neumann熵
量子纠缠 相似文献
19.
Quantum entanglement between the two-mode fields and atomic entropy squeezing in the system of a moving atom interacting with two-mode entangled coherent field 下载免费PDF全文
This paper investigates the entropy squeezing of a moving two-level
atom interacting with the two-mode entangled coherent field via
two-photon transition by using an entropic uncertainty relation and the
degree of entanglement between the two-mode fields by using quantum
relative entropy. The results obtained from numerical calculation
indicate that the squeezed period, the duration of entropy squeezing
and the maximal squeezing can be controlled by appropriately
choosing the intensity of the light field, the atomic motion and the
field-mode structure. The atomic motion leads to the periodic
recovery of the initial maximal degree of entanglement between the
two-mode fields. Moreover, there exists a corresponding relation
between the time evolution properties of the atomic entropy
squeezing and those of the entanglement between the two-mode fields. 相似文献
20.
Eyob Alebachew 《Optics Communications》2007,280(1):133-141
We consider a non-degenerate three-level cascade laser coupled to a two-mode squeezed vacuum reservoir via the lossy single-port mirror. Applying the pertinent master equation, we analyze the effects of the injected squeezed light on the quadrature squeezing, entanglement and normalized intensity difference fluctuations. We show that the injected squeezed light considerably enhances the degree of squeezing and entanglement in the two-mode light for certain initial conditions. Moreover, the injected squeezed light increases the mean photon number where the squeezing and entanglement is significant. We also show that the presence of the injected squeezed light greatly reduces the noise in the intensity difference. 相似文献