共查询到20条相似文献,搜索用时 46 毫秒
1.
In this paper we consider the problem of the interaction between two SU(2) quantum systems namely: two-level atom and multi-level atoms. The evolution operator is obtained and used to calculate the time-dependent dynamical operators. It has shown that the atomic inversion is sensitive to the change in the detuning parameter ?, the quantum numbers jk as well as the atomic angles. The atomic squeezing is also considered and the phenomenon of squeezing is observed in both quadrature variances, however, with a periodic exchange between the quadratures. The degree of entanglement is examined by employing von Neumann entropy. It has shown that an increase in the value of the detuning parameter leads to a decrease in the degree of entanglement. However, for a weak coupling parameter the system shows reduction in the entropy. In the meantime the maximum entanglement can be reached when we increase the value for the quantum numbers jk. Also it has shown that the atomic angles play a role for controlling the degree of entanglement. 相似文献
2.
M. Sebawe Abdalla M. M. A. Ahmed R. N. Rabea 《International Journal of Theoretical Physics》2016,55(6):2722-2734
We study the interaction between a single two-level atom and N two-level atoms under the effect of a uniform magnetic field. The exact solution is obtained and the expectation value of the time-dependent quantum operators calculated using the Block state (the generalized coherent state). We discuss numerically the atomic inversion where the phenomenon of collapse and revival is observed. The change in the value of the atomic angle plays a role in variance squeezing, where it is pronounced for ?? = π/3. Entropy squeezing is discussed and occurred in the first quadrature. The degree of entanglement through linear entropy is examined where the system shows partial entanglement and at a certain value of parameters displays nearly maximum entanglement. 相似文献
3.
运用量子信息熵理论,研究了运动二能级原子与光场依赖强度纠缠下最佳熵压缩态的制备和控制;比较了分别从基于信息熵不确定关系和海森堡不确定关系出发得出的结果;分析了制备原子最佳熵压缩态的充要条件,并进行了数值验证.考察了场模结构参数对最佳熵压缩态的影响.结果表明,信息熵压缩是对原子压缩效应的高灵敏量度;控制原子与场的相互作用时间,斩断原子和场的纠缠,选择原子的相干性,调节系统的相对位相可制备原子最佳熵压缩态;控制场模结构参数,可获得持续的原子最佳熵压缩态.
关键词:
依赖强度耦合
场模结构参数
最佳熵压缩态 相似文献
4.
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
5.
Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process 下载免费PDF全文
Based on the quantum information theory, we have investigated the
entropy squeezing of a moving two-level atom interacting with the
coherent field via the quantum mechanical channel of the two-photon
process. The results are compared with those of atomic squeezing
based on the Heisenberg uncertainty relation. The influences of the
atomic motion and field-mode structure parameter on the atomic
entropy squeezing and on the control of noise of the quantum
mechanical channel via the two-photon process are examined. Our
results show that the squeezed period, duration of optimal entropy
squeezing of a two-level atom and the noise of the quantum mechanical
channel can be controlled by appropriately choosing the atomic motion
and the field-mode structure parameter, respectively. The quantum
mechanical channel of two-photon process is an ideal channel for
quantum information (atomic quantum state) transmission. Quantum
information entropy is a remarkably accurate measure of the atomic
squeezing. 相似文献
6.
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
7.
We discuss the correlation and entanglement of a three-level atom with a single-mode quantized field in a coherent state inside a phase-damped cavity. We analyze the influence of dissipation on the quantum and classical entropy. It has been shown that the quantum, classical and nonextensive entropy are sensitive to any change in the initial state setting of the atom and the quantized field. The relation between the long lived entanglement and dissipation is observed. On the other hand, a short disentanglement can be generated through special values of the atomic motion parameter. 相似文献
8.
与量子光场相互作用的运动原子的熵压缩 总被引:9,自引:1,他引:8
运用量子信息熵理论,研究了与量子光场相互作用的二能级运动原子的熵压缩,讨论了原子运动和场模结构对原子熵压缩的影响,并且比较了分别从基于信息熵测不准关系和海森伯测不准关系出发得出的结果,表明原子的运动导致了原子熵压缩的周期性演化;随着场模结构参量的增大,熵压缩的演化周期缩短,压缩时间延长;选择适当的系统参量,运动原子能够呈现长时间的持续熵压缩效应。当原子反转为零时,基于海伯堡测不准关系的方差压缩定义不再有效,而熵压缩实现了对原子压缩效应的高灵敏量度。 相似文献
9.
Preparation and control of atomic optimal entropy squeezing states for a moving two-level atom under control of the two-mode squeezing vacuum fields 下载免费PDF全文
From the viewpoint of quantum information,this paper studies preparation and control of atomic optimal entropy squeezing states(AOESS) for a moving two-level atom under control of the two-mode squeezing vacuum fields.Necessary conditions of preparation of the AOESS are analysed,and numerical verification of the AOESS is finished.It shows that the AOESS can be prepared by controlling the time of the atom interaction with the field,cutting the entanglement between the atom and field,and adjusting squeezing factor of the field.An atomic optimal entropy squeezing sudden generation in different components can alternately be realized by controlling the field-mode structure parameter. 相似文献
10.
G. Yu. Kryuchkyan 《Optics and Spectroscopy》2007,103(1):67-75
Quantum entanglement and intensity correlations in continuous variable (CV) regimes have investigated in the time domain in
addition to many analogous investigations performed in the frequency domain. The specific signatures of time-resolved CV quadrature
entanglement and intensity difference squeezing have been analyzed for periodically-pulsed optical parametric oscillator (OPO).
An application to quantum key distribution scheme based on intensity correlation of twin beams has also been considered.
The text was submitted by the author in English. 相似文献
11.
Xi-Wen Hou Ming-Fang Wan Zhong-Qi Ma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(2):279-288
Various measures of entanglement have triggered considerable interest in the
relationship between entanglement measures and other
well-known quantities. As a demonstration, the dynamical
correlation of negativity and entropy is studied in two
coupled quartic oscillators for initial pure and mixed states that
are respectively taken to be the products and mixed density
matrices of coherent states and squeezed states on each
oscillator. The correlation with energy is also considered.
It is shown that for the initial pure states with a
small magnitude, two negativities are
positively correlated with the von Neumann entropy while they are anti-correlated with
the energy of each oscillator in the weak coupling regime. For mixed states
with a small magnitude the two negativities and the mutual entropy exhibit dominantly
positive correlation, whereas those three quantities are
dominantly anti-correlated with the sum of energies of two
oscillators in the case of weak interactions. Such correlation behaviors in the mixed
state with small magnitudes are most striking at the same step in
maximal and minimal values and in oscillation. The differences in
entropies and negativities between coherent states and squeezed
states are discussed. These are useful for quantum
entanglement and quantum information processing. 相似文献
12.
Yong Hong Ma E. Wu Xue-Feng Zhang Yu-He Dong Xiang-Gang Han 《International Journal of Theoretical Physics》2011,50(10):3205-3211
A quantum well in a microcavity driven by an external field is studied. Applying a linearized fluctuation analysis, single
mode quadrature squeezing spectra as well as continuous-variable (CV) entanglement between the cavity field and exciton are
investigated. It shows that a maximum squeezing can be achieved by choosing appropriate quadrature angles for different nonlinearities.
More importantly, CV entanglement can be generated in this scheme. 相似文献
13.
Optimal entropy squeezing sudden generation and its control for an effective two-level moving atom entanglement with the two-mode coherent fields 下载免费PDF全文
From the viewpoint of quantum information, this paper proposes a
concept and a definition of the atomic optimal entropy squeezing
sudden generation (AOESSG) for the system of an effective two-level
moving atom which entangles with the two-mode coherent fields. It
also researches the relationship between the AOESSG and
entanglement sudden death of the atom-fields, and discusses the
influences of atomic initial state on the AOESSG and obtains the
system parameter which controls the AOESSG. 相似文献
14.
基于单-双模组合压缩真空态一定范围内能够获得压缩增强的效果,引入单-双模组合压缩热态(DSMST),讨论其纠缠性质.利用Weyl编序算符在相似变换下的不变性,简洁方便地导出了DSMST的纠缠度-负对数值,并给出了当热效应存在时保持纠缠的条件.研究表明:与通常的双模压缩态相比,随着参数的增加,DSMST的纠缠度增加.作为DSMST的应用,利用其实现相干态的量子隐形传输.结果表明:不同于纠缠度随压缩参数增加,保真度获得改善是有条件的,该条件恰好就是一正交分量涨落出现压缩增强的参数区域.此外,解析推导了有效隐形传输保真度(1/2)的条件. 相似文献
15.
The problem of the interaction between two quantum systems namely SU(1,1) and SU(2) is considered. Using the evolution operator technique, an exact solution of the wave function and consequently the density matrix are obtained. The entropy squeezing is examined and it has shown that, different values of the relative phase angle ? as well as the coupling parameter λ lead to different observation of the squeezing in the quadratures. In the meantime, we have shown that the entropy squeezing is also sensitive to the variation in the state angle θ, the detuning parameter Δ in addition to the excitation number m. Moreover, for a large value of the detuning parameter there is a weak entanglement between the atom and the quantum system and vice versa. Furthermore, we find that the Q-function is sensitive to the variation in the excitation number m in addition to the Bargmann index k where the nonclassical effect is pronounced for the even parity. 相似文献
16.
We propose a scheme employing quantum-reservoir engineering to controllably entangle the internal states of two atoms trapped in a high-finesse optical cavity. Using laser and cavity fields to drive two separate Raman transitions between stable atomic ground states, a system is realized corresponding to a pair of two-state atoms coupled collectively to a squeezed reservoir. Phase-sensitive reservoir correlations lead to entanglement between the atoms, and, via local unitary transformations and adjustment of the degree and purity of squeezing, one can prepare entangled mixed states with any allowed combination of linear entropy and entanglement of formation. 相似文献
17.
利用半经典理论方法计算了运转于阈值以上的非简并光学参量振荡腔输出信号场、闲置场及反射抽运场的关联特性. 根据 van Loock 等提出的连续变量多组分纠缠判据, 计算结果表明, 常温下这三个光场的正交振幅分量与正交位相分量之间存在三组分量子关联, 得到了三色三组分纠缠态光场. 数值计算了关联噪声对参量振荡腔物理参数的依赖关系, 找出了产生三色三组分纠缠态产生的最佳运转条件, 为连续变量多组分纠缠态光场产生系统的设计提供了直接参考.
关键词:
连续变量
非简并光学参量振荡腔
三色三组分纠缠态 相似文献
18.
19.
We investigate the dynamics of two qubits coupled with a quantum oscillator by using the adiabatic approximation method. We take account of the interaction between the qubits and show how the entanglement is affected by the interaction parameter. The most interesting result is that we can prolong the entanglement time or improve the entanglement degree by using an appropriate interaction parameter. As the generation and preservation of entanglement of qubits are crucial for quantum information processing, our research will be useful. 相似文献
20.
C. Trallero-Giner V. López-Richard Y. Núñez-Fernández M. Oliva G. E. Marques M. C. Chung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(7):1-5
Quadrature squeezed cylindrically polarized modes contain entanglement not only in the polarization and spatial electric field variables but also between these two degrees of freedom [C. Gabriel et al., Phys. Rev. Lett. 106, 060502 (2011)]. In this paper we present tools to generate and detect this entanglement. Experimentally we demonstrate the generation of quadrature squeezing in cylindrically polarized modes by mode transforming a squeezed Gaussian mode. Specifically, ?1.2 dB ± 0.1 dB of amplitude squeezing are achieved in the radially and azimuthally polarized mode. Furthermore, theoretically it is shown how the entanglement contained within these modes can be measured and how strong the quantum correlations are, depending on the measurement scheme. 相似文献