利用分束器产生的一类非经典光学态

A Kind of Nonclassical Optical States Generated by Beam Splitter

把相干态和任意粒子数态作为分束器的输入态,通过条件测量可以得到被剪切了的输出态。本文研究了这些剪切了的输出态的性质。结果显示,当在某一输出端测量到零个光子时,在另一输出端得到的剪切了的输出态呈现较强的压缩和亚泊松分布等非经典效应,而且这种非经典效应受输入粒子数态的粒子数的影响,即输入粒子数态的粒子数较大时其非经典性相对较强．当在其中一个输出端测量到m(m＞0)个光子时,条件测量后的各输出态在光场性质上表现类似,但也都呈现出明显的压缩和亚泊松分布等非经典效应。尤其值得注意的是,当输入的是单粒子数态时,条件测量后的输出态中与测量相对应的粒子数态被剪去。

Truncated output states can be generated by the conditional measurement if the coherent state and arbitrary Fock state are regarded as the input states of beam splitters. The properties of this kind of truncated optical states are studied in this paper. The results have shown that the output states in one out port have stronger nonclassical properties of squeeze and sub-Poissonian distribution when zero photon is measured in the other out port, and the nonclassical properties can become stronger with the increase of input number state. When m（m 〉 0） photon is measured in one of the out ports, each output state after conditional measurement has the same property in optical field but also exhibits apparent nonclassical effects such as squeezing and sub-Poissonian distribution. It should be noted particularly that the number state corresponding to the measurement in output state after conditional measurement would be truncated if the single number state is input.