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Conditional Production of Superpositions of Coherent States with Inefficient Photon Detection

A. P. Lund·H. Jeong·T. C. Ralph·M. S. Kim
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Abstract

It is shown that a linear superposition of two macroscopically distinguishable optical coherent states can be generated using a single photon source and simple all-optical operations. Weak squeezing on a single photon, beam mixing with an auxiliary coherent state, and photon detecting with imperfect threshold detectors are enough to generate a coherent state superposition in a free propagating optical field with a large coherent amplitude ($α>2$) and high fidelity ($F>0.99$). In contrast to all previous schemes to generate such a state, our scheme does not need photon number resolving measurements nor Kerr-type nonlinear interactions. Furthermore, it is robust to detection inefficiency and exhibits some resilience to photon production inefficiency.

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A. P. Lund, H. Jeong, T. C. Ralph, M. S. Kim. 2004-07-02. Conditional Production of Superpositions of Coherent States with Inefficient Photon Detection. https://doi.org/10.1103/physreva.70.020101

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