标题： 挤压态光的蒸馏和纯化扩展分析 显示英文标题

标题： Extended analysis of distillation and purification of squeezed states of light

摘要： 压缩光态是量子光学、光学量子信息处理和量子传感中最重要的基本资源之一。最近，实验上已经证明，通过概率性双光子减法可以增强单模压缩真空态的压缩度。随后，通过预告高斯化可以从非高斯化的双光子减法态中提炼出高斯态，从而进一步提高压缩度。在这里，我们提供了对压缩度浓缩和纯化的扩展理论分析。我们考虑了一个更一般的方案，其中将光子减法与弱相干位移相结合。这种更灵活的方案允许对任意输入压缩值增强压缩度。此外，如果适当选择修改后的双光子减法操作，则可以通过后续的高斯化提炼出任意强的压缩度。我们超越了纯态，表明光子减法和预告高斯化的结合无法抑制已影响输入态的损耗。为了克服这一限制，我们提出了一种基于福克态滤波器的替代非高斯化操作，该操作可以去除单光子态。通过这种非高斯化操作和随后的再高斯化，可以从一大类混合输入态中提炼出纯的单模压缩态。有趣的是，我们发现通过双光子减法进行的压缩度浓缩与生成Gottesman-Kitaev-Preskill (GKP)态的某些方法密切相关，而GKP态对于光学量子计算至关重要。 显示英文摘要

摘要： Squeezed states of light are one of the most important fundamental resources for quantum optics, optical quantum information processing and quantum sensing. Recently, it has been experimentally demonstrated that the squeezing of single-mode squeezed vacuum states can be enhanced by probabilistic two-photon subtraction. A further enhancement of the squeezing is subsequently possible by heralded Gaussification that distills a Gaussian state from the de-Gaussified two-photon subtracted state. Here we provide an extended theoretical analysis of squeezing distillation and purification. We consider a more general scheme in which photon subtraction is combined with a weak coherent displacement. This more flexible scheme allows to enhance squeezing for arbitrary input squeezing value. Moreover, if the modified two-photon subtraction operation is properly chosen, then arbitrary strong squeezing can be distilled by subsequent Gaussification. We go beyond pure states and show that the combination of photon subtraction and heralded Gaussification cannot suppress losses that have affected the input state. To overcome this limitation, we propose an alternative de-Gaussifying operation based on a Fock-state filter that removes the single-photon state. With this de-Gaussifying operation and subsequent re-Gaussification, pure single-mode squeezed states can be distilled from a large class of mixed input states. Interestingly, we have found that squeezing distillation by two-photon subtraction is closely related to certain methods for generating Gottesman-Kitaev-Preskill (GKP) states, which are crucial for optical quantum computing.