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Conditional quantum-state transformation at a beam splitter

J. Clausen·M. Dakna·L. Knoll·D. -G. Welsch
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Abstract

Using conditional measurement on a beam splitter, we study the transformation of the quantum state of the signal mode within the concept of two-port non-unitary transformation. Allowing for arbitrary quantum states of both the input reference mode and the output reference mode on which the measurement is performed, we show that the non-unitary transformation operator can be given as an $s$-ordered operator product, where the value of $s$ is entirely determined by the absolute value of the beam splitter reflectance (or transmittance). The formalism generalizes previously obtained results that can be recovered by simple specification of the non-unitary transformation operator. As an application, we consider the generation of Schrödinger-cat-like states. An extension to mixed states and imperfect detection is outlined.

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J. Clausen, M. Dakna, L. Knoll, D. -G. Welsch. 1998-11-24. Conditional quantum-state transformation at a beam splitter. https://doi.org/10.1088/1464-4266/1/3/306

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