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1.
We report on the observation of new features in a superconducting charge qubit system. The system we analyze comprises of a single Cooper-pair box sequentially coupled to two microwave cavity fields. Simulations of the full qubit–field dynamics show significant total correlation and coherence loss. By suitably choosing the system’s parameters and precisely controlling the dynamics, we demonstrate the generation of two-mode field states. We explore the nonclassical behavior of the system by studding the quasi-probability distribution function. Our scheme can be realized within the current experimental technology and may well be of use in quantum information processing applications.  相似文献   

2.
The nonclassical and non-Gaussian quantum states—photon-added two-mode squeezed coherent states have been theoretically introduced by adding multiple photons to each mode of the two-mode squeezed coherent states. Starting from the new expression of two-mode squeezing operator in entangled states representation, the normalization factor is obtained, which is directly related to bivariate Hermite polynomials. The sub-Poissonian photon statistics, cross-correlation between two modes, partial negative Wigner function are observed, which fully reflect the nonclassicality of the target states. The negative Wigner function often display non-Gaussian distribution meanwhile. The investigations may provide experimentalists with some better references in quantum engineering.  相似文献   

3.
A scheme for teleporting two-mode entangled photon states with the successful probability 33.3% is Proposed. In the sehane, the tdeported qubit is two-mode photon entangled states, and two pairs of EPR pair are usedas quantum channel between a sender and a recciver. This procedure is achieved by using two 50/50 symmetric beam aplitters and four photon number detectors with the help of classical information.  相似文献   

4.
邹健  邵彬  邢修三 《物理学报》1997,46(11):2233-2240
研究了直流偏置电压下介观约瑟夫森结在SU(1,1)双模相干态光场作用下超流的动力学行为、流压台阶和直流分量等特性.研究发现超流能够呈现明显的崩塌与复苏现象,对于经典电磁场和非耦合的双模相干态光场作用下的情况,超流不出现此现象,且其流压台阶结构与后两种情况也不相同. 关键词:  相似文献   

5.
刘小娟  方卯发 《中国物理》2003,12(9):971-976
We investigate the entanglement properties of the two-mode coherent fields interacting with a two-level atom via the two-photon transition. We discuss the quantum entanglement between the two-mode coherent fields and the two-level atom by using the quantum reduced entropy and that between the two-mode coherent fields by using the quantum relative entropy. We also examine the influences of the initial states of the atom and the two-mode coherent fields on the quantum entanglement of the system. Our results show that three types of entangled states can be prepared via the two-mode coherent fields interacting with a two-level atom and choosing appropriately the initial-state parameters of the system.  相似文献   

6.
利用双模压缩真空态实现量子态的远程传输   总被引:2,自引:0,他引:2       下载免费PDF全文
宋同强 《物理学报》2004,53(10):3358-3362
借助于双模压缩真空态在EPR纠缠态表象中的表示,研究了用双模压缩真空态作为量子通道 实现任意的单模和双模量子态的远程传输. 关键词: 量子隐形传态 EPR纠缠态 压缩真空态  相似文献   

7.
We propose a scheme for teleportation of an arbitrary two-mode N-photon entangled states in cavity QED. The scheme is based on the resonant interaction between Λ-type atoms and two-mode cavity fields. In contrast to all the theoretical schemes proposed previously in cavity QED for teleportation of two-mode cavity field states, in the present scheme, the established entanglement for the quantum channel is the type of the multi-dimensional entanglement between the symmetric multi-atom Dicke states and two-mode N-photon states. Therefore, the scheme extends the scope of the theoretical study of the teleportation.  相似文献   

8.
We propose a unidimensional two-way continuous-variable quantum key distribution protocol with coherent states, where the sender modulates a single quadrature of the coherent states rather than both quadratures to simplify the structure of a two-way system. Security analysis is performed with a general attack strategy, known as two-mode attack, which helps to reduce limitations in the analysis. The performance of the protocol under all accessible two-mode attacks at fixed distance is illustrated. Further, two typical two-mode attack strategies are obtained from it, which are one-mode attack strategy and optimal two-mode attack strategy. Between them, the one-mode attack is the simplest form of the two-mode attack, while the optimal two-mode attack is the most complicated one. Simulations show that though the system is simplified, the performance of the two-way protocol with unidimensional modulation is still comparable to that of the counterpart with Gaussian modulation even against the optimal two-mode attack when Eve’s ability is maximized. Thus, the proposed protocol simplifies the two-way system while guaranteeing its performance to a certain extent. Especially in a practical system with short transmission distance and high excess noise, the protocol has a good application prospect.  相似文献   

9.
刘小娟  周并举  刘明伟  李寿存 《中国物理》2007,16(12):3685-3691
We investigate the preparation and the control of entangled states in a system with the two-mode coherent fields interacting with a moving two-level atom via the two-photon transition. We discuss entanglement properties between the two-mode coherent fields and a moving two-level atom by using the quantum reduced entropy, and those between the two-mode coherent fields by using the quantum relative entropy. In addition, we examine the influences of the atomic motion and field-mode structure parameter $p$ on the quantum entanglement of the system. Our results show that the period and the duration of the prepared maximal atom-field entangled states and the frequency of maximal two-mode field entangled states can be controlled, and that a sustained entangled state of the two-mode field, which is independent of atomic motion and the evolution time, can be obtained, by choosing appropriately the parameters of atomic motion, field-mode structure, initial state and interaction time of the system.  相似文献   

10.
本文研究了在两个耦合的量子点和腔QED系统中的双模激子的压缩性质.讨论了不同的初始光场对双模激子的正常压缩与和压缩的影响.计算表明,当初始态光场制备在相干态时,双模激子既不存在正常压缩,也不存在和压缩,这说明双模激子振辐的两个正交分量具有相同的量子涨落;然而,当初始腔场处于压缩真空态时,无论是正常压缩还是和压缩,双模激子振辐的两个正交分量总有一个存在压缩.这意味着量子噪声能被有效的得到抑制.此外,两种情形下的最大压缩都由初始腔场的压缩因子r决定.经过比较,我们还发现双模激子的正常压缩比和压缩大.  相似文献   

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