共查询到20条相似文献,搜索用时 609 毫秒
1.
Eyob Alebachew Sete 《Optics Communications》2008,281(24):6124-6129
We show that a two-mode three-level cascade laser driven by external coherent fields generate intense entangled light. It turns out that external driving fields which are at resonance with the cavity modes substantially improve the intensity of the two-mode light in the cavity in a region where the squeezing and entanglement is significant making the system under consideration a viable source of bright squeezed as well as entangled light. 相似文献
2.
A Theoretical Scheme for Entanglement Transfer under Intensity-Dependent Couplings 总被引:2,自引:0,他引:2 下载免费PDF全文
We consider a theoretical scheme for entanglement transfer between a two-mode squeezed vacuum field and two initially separable atoms through intensity-dependent couplings. We find that the entanglement transfer between the field and the atoms has an exact period for any given squeezing. We also find that the maximum achievable entanglement of the atomic subsystem is a simple increasing function of r.For sufficiently large squeezing parameter r, it is possible for the atoms to be entangled into a Bell state at half the periodic time points. 相似文献
3.
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
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.
Hua-tang Tan Shi-yao Zhu M. Suhail Zubairy 《量子光学学报》2006,12(B08):83-83
We discuss the generation and evolution of entangled light in a correlated spontaneous emission laser in the linear regime. The master equation for the two-mode cavity field is derived and solved analytically in phase space. The time-dependent characteristic function in the Wigner representation for the two-mode field is obtained. It shows that the two-mode field in the cavity evolves in a two-mode Gaussian state. The entanglement degree of the two- mode field in the cavity increases initially, then decreases, and finally vanishes as the field evolves from an initial vacuum. The period of the entanglement is extended as the intensity of the driving field is increased. It is found that the entanglement still exists even when the two-mode squeezing disappears. During the entanglement period, the intensity of the field is amplified. The entanglement for the initial field being a two-mode squeezed vacuum and the entanglement of the output field are also discussed. 相似文献
6.
We present a realistic scheme for the entanglement swapping of continuous
variable, in which a two-mode squeezed vacuum state serves as a quantum
channel. The position sum and momentum difference of two local modes are
measured. By taking the input entangled state also as a two-mode squeezed
vacuum state, we investigate the average fidelity and the von Neumann
entropy of the output state. The results show that the
perfect teleportation can be
achieved by increasing the squeezing of the quantum channel and that any
nonzero squeezing in both the quantum channel and the input entangled state
is sufficient to swap the entanglement. 相似文献
7.
FAN Hong-Yi WANG Hui 《理论物理通讯》2001,(10)
We discuss the entanglement swapping of two pairs of displaced two-mode squeezed states and find that the squeezing parameter of the outcoming squeezed state is less than that of the originM squeezed states. The calculation is greatly simplified by virtue of the natural expression of the two-mode squeezing operator in EPR eigenstate representation. A protocol for such entanglement swapping is proposed.`` 相似文献
8.
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
9.
10.
Single-mode quadrature-amplitude measurement for generalized two-mode squeezed states studied by virtue of the entangled state representation 下载免费PDF全文
The result of one-mode quadrature-amplitude measurement for some generalized two-mode squeezed states has been studied by virtue of the entangled state representation of the corresponding two-mode squeezing operators. We find that the remaining field-mode simultaneously collapses to the single-mode squeezed state with more stronger squeezing. The measurement result caused by a single-mode squeezed state projector is also calculated, which indicates quantum entanglement in squeezing. 相似文献
11.
In this paper, the squeezing properties of the probe light field in the process preparing Raman-type atom laser via stimulated Raman transition of the sodium atom Bose-Einstein condensate (BEC) interacting with two light beam of a weaker squeezed coherent probe light and a stronger classical pump light are studied. The results show that the probe light can be periodically squeezed. The squeezing period is related to the mean number of atoms in trap, the strength of interaction between squeezed light and BEC atoms, and the detuning of the light, and the squeezing depth is determined by the initial squeezing factor of the probe light. 相似文献
12.
Using the two-mode two-photon Jaynes-Cummings model, entanglement transfer between atoms and field is studied. It is found that when the field is in state constructed from the two-mode photon number states |00〉,|11〉 or the two-mode squeezed vacuum states, full entanglement exchange can be attained no matter the atoms are initially in pure or mixed states. These investigations show that CV entangled states can act as perfectly as the entangled number states in entangling initially separable atoms. The two-mode two-photon atom-field interaction also provides a simple way for the quantum teleportation of atomic or field states. 相似文献
13.
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
14.
We propose to generate two-mode squeezed vacuum motional state of an intracavity trapped ion by taking the advantage of the dissipation of the cavity mode. At the first step, the steady and pure two-mode motional entanglement between two motional degrees of the cold ion is obtained by engineering the couplings of both the motional modes of the ion to the cavity field. Based on the first step, a two-mode squeezed vacuum motional state is then generated by manipulating the phases of the external laser pulses incident on the ion. 相似文献
15.
Eyob Alebachew 《Optics Communications》2007,273(2):488-495
We present the quantum statistical properties of the light produced by a degenerate three-level cascade laser with the cavity mode driven by coherent light. In this system three-level atoms in a cascade configuration, initially prepared in a coherent superposition of the top and bottom levels, are injected into a cavity coupled a vacuum reservoir. We find that although the driving coherent light has no effect on the degree of squeezing, it increases the mean photon number considerably. Therefore, this quantum optical system can be taken as a source of a bright squeezed light. 相似文献
16.
We investigate the entanglement swapping of continuous state and the two-mode squeezed vacuum which is exposed variable using the pair coherent state as the input in a phase decoherence environment as the quantum channel. By adopting the log-negativity as the measure of entanglement, we analyze how entanglement of the two initial states and the phase decoherence environment affect the entanglement swapping quality. 相似文献
17.
相位锁定是双模压缩微波制备的关键问题之一.针对基于超导180°混合环的制备方案相位稳定度不高且信息处理复杂等问题,提出一种相位锁定方案.对约瑟夫森参量放大器的信号输入进行相位调制,输出的单模压缩微波与另一未调制的同频单模压缩微波在超导180°混合环内干涉,实现双模压缩微波的制备与路径分离.将未调制的单模压缩微波与一路双模压缩微波混频,解调出相位调制信号可得到两路单模压缩微波的相对相位及误差,将相位误差反馈于约瑟夫森参量放大器的抽运实现相对相位的锁定,获得稳定的双模压缩输出.本研究对高性能纠缠微波源的设计提供了理论参考. 相似文献
18.
19.
Applying the recently developed formalism of quantum-state transformation of light at absorbing dielectric four-port devices [5], we calculate the quantum state of the outgoing modes of a two-mode squeezed vacuum transmitted through optical fibers of given extinction coefficients. Using the Peres-Horodecki separability criterion for continuous variable systems [4], we then compute both the maximal length of transmission of a two-mode squeezed vacuum through an absorbing system for which the transmitted state is still inseparable and the maximal gain for which inseparability can be observed in an amplifying setup. Finally, we estimate an upper bound of the entanglement preserved after transmission through an absorbing system. The results show that the characteristic length of entanglement degradation drastically decreases with increasing strength of squeezing. 相似文献
20.
We consider the system of free scalar field, which is assumed to be a two-mode squeezed state from an inertial point of view. This setting allows the use of entanglement measure for continuous variables, which can be applied to discuss free and bound entanglement from the point of view from non-inertial observer. 相似文献