Continuous-variable codes are an expedient solution for quantum information processing and quantum communication involving optical networks. Here we characterize the squeezed comb, a finite superposition of equidistant squeezed coherent states on a line, and its properties as a continuous-variable encoding choice for a logical qubit. The squeezed comb is a realistic approximation to the ideal code proposed by Gottesman et al. [D. Gottesman, A. Kitaev, and J. Preskill, Phys. Rev. A 64, 012310 (2001)], which is fully protected against errors caused by the paradigmatic types of quantum noise in continuous-variable systems: damping and diffusion. This is no longer the case for the code space of finite squeezed combs, and noise robustness depends crucially on the encoding parameters. We analyze finite squeezed comb states in phase space, highlighting their complicated interference features and characterizing their dynamics when exposed to amplitude damping and Gaussian diffusion noise processes. We find that squeezed comb states are more suitable and less error prone when exposed to damping, which speaks against standard error-correction strategies that employ linear amplification to convert damping into easier-to-describe isotropic diffusion noise.

中文翻译：

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压缩梳状

连续变量代码是涉及光网络的量子信息处理和量子通信的便捷解决方案。在这里，我们将压缩梳状结构，行上等距压缩相干态的有限叠加定为特征，并将其特性作为逻辑量子位的连续变量编码选择。压缩的梳子是对Gottesman等人提出的理想代码的逼真的近似。[D. Gottesman，A。Kitaev和J.Preskill，物理学。版本A 64，012310（2001）]，它可以完全防止由于连续变量系统中的量子噪声的范式引起的错误：阻尼和扩散。有限压缩梳的代码空间不再是这种情况，并且噪声鲁棒性主要取决于编码参数。我们分析了相空间中的有限压缩梳状，突出了它们的复杂干扰特征，并在暴露于振幅阻尼和高斯扩散噪声过程时表征了它们的动力学。我们发现，当受到阻尼作用时，压缩梳状态更合适且更不易出错，这与采用线性放大将阻尼转化为易于描述的各向同性扩散噪声的标准误差校正策略相抵触。