Linear optical quantum gates have been proposed as a possible implementation for quantum computers. Most experimental linear optical quantum gates are constructed with free-space optical components with negligible loss. In this work, we analyze symmetric and asymmetric partially polarizing lossy beam splitters. Using the generalized beam splitter equations, we study the effects of loss on two linear optical quantum gates: the first is a commonly used CNOT gate, and the second is a W state expansion gate. Envisioning inherent loss in plasmonics and metamaterials as a new degree of freedom and those materials systems as a route for miniaturization, we reconsider the requirements of the lossy CNOT gate and show it is possible to simplify the three-beam-splitter design to a single beam splitter without sacrificing success probability.

中文翻译：

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损耗对线性光量子逻辑门的影响

已经提出线性光学量子门作为量子计算机的可能实现。大多数实验线性光量子门都是由损耗可忽略的自由空间光学组件构成的。在这项工作中，我们分析了对称和非对称部分偏振有损分束器。使用广义分束器方程，我们研究了损耗对两个线性光量子门的影响：第一个是常用的 CNOT 门，第二个是 W 态扩展门。将等离子体和超材料的固有损耗视为新的自由度，将这些材料系统视为小型化的途径，我们重新考虑有损 CNOT 门的要求，并表明可以将三分束器设计简化为单光束不牺牲成功概率的分离器。