Quantum Properties of Two-Mode Squeezed Even and Odd Coherent States

Two new types of quantum states are constructed by applying the operator s（ξ） = exp（ξ＊ ab - ξa＋b＋） on the two-mode even and odd coherent states. The mathematical and quantum statistical properties of such states are investigated. Various nonclassical features of these states, such as squeezing properties, the inter-mode photon bunching, and the violation of Cauchy-Schwarz inequality, are discussed. The Wigner function in these states are studied in detail.

Photon statistical properties of photon-added two-mode squeezed coherent states

We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states （PA- TMSCS）. We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS. Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PA- TMSCS. Compared with that of the TMSCS, the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode; further, that the photon addition essentially shifts the photon number distribution.

Entanglement Properties of Two-Mode Squeezed Coherent States in Radiation Field

Entanglement properties of two-mode squeezed coherent states in the radiation field ＆re investigated according to the entanglement criterion [Phys. Rev. Lett. 84 （2000） 2722]. The dependence of entanglement on squeeze angle and squeeze parameter is discussed. It shows that the system evolves into entangled states and entanglement does not increase persistently with the increase of squeeze angle and squeeze parameter. There only exists a certain squeeze angle in which the entanglement exists continuously.

Squeezing and displacing related two-mode squeezed coherent state

A type of special two-mode squeezed coherent state is constructed which is a characteristic of squeezing and displacing related. The new states take simpler and neater form than the usual two-mode squeezed coherent states, and also possess a completeness relation. It is expected that experimentalists woking on quantum optics should fabricate such a type of squeezed coherent optical field.

Nonstandard Unitary Transformations of Quantum States

In quantum optics, unitary transformations of arbitrary states are evaluated by using the Taylor series expansion. However, this traditional approach can become cumbersome for the transformations involving non-commuting operators. Addressing this issue, a nonstandard unitary transformation technique is highlighted here with new perspective. In a spirit of “quantum” series expansions, the transition probabilities between initial and final states, such as displaced, squeezed and other nonlinearly transformed coherent states are obtained both numerically and analytically. This paper concludes that, although this technique is novel, its implementations for more extended systems are needed.

叠加激发相干态的量子特性

构造了2个强度相同位相不同的激发相干态的叠加态,并通过数值计算研究了该叠加态的反聚束效应和振幅平方压缩效应随激发光子数m、光场强度x和相位差θ的变化,结果表明:随激发光子数m和光场强度x增大,该量子态的振幅平方压缩均会加深;压缩效应与相位差θ有密切的关系;随光场强度x的增大和激发光子数m的增大,其反聚束效应减弱.

原子系综双模压缩叠加相干态的制备和性质

提出了一个在双模腔中制备原子系综双模压缩叠加相干态的方案.此外,还讨论了所制备态的非经典性质.结果表明,双模压缩相干叠加态具有更强的非经典性质.

叠加压缩相干态的量子统计性质

研究了叠加压缩相干态的量子统计性质,给出了压缩和反聚束效应与叠加系数之间的关系。结果表明,叠加压缩相干态具有压缩和反聚束的现象。压缩奇偶相干态的有关结果均作为特例包含在本文的一般结论之中。

双模压缩叠加相干态的非经典性质

本文描述辐射场的一类新的非经典态,称之为双模压缩叠加相干态,其定义式为:|φ〉=CS(ξ)(|1α,2α〉+eiφ|1α*,α2*〉).通过它的归一化常数的计算,讨论其非经典性质,即压缩效应、亚泊松分布、光子反聚束效应以及两模间二阶相关函数。数值计算结果表明,双模压缩叠加相干态具有更为显著的非经典性质,只要我们适当地选择参数1α,2α,φ,θ和ξ,双模压缩叠加相干态就可以约化成双模压缩叠加真空态和双模叠加相干态,因此双模压缩叠加相干态是更广泛的一类非经典光场态。