Homodyne measurement with a Schrodinger cat state as a local oscillator

Homodyne measurements are a widely used quantum measurement. Using a coherent state of large amplitude as the local oscillator, it can be shown that the quantum homodyne measurement limits to a field quadrature measurement. In this work, we give an example of a general idea: injecting nonclassical states as a local oscillator can lead to nonclassical measurements. Specifically, we consider injecting a superposition of coherent states, a Schrodinger cat state, as a local oscillator. We derive the Kraus operators and the positive operator-valued measure in this situation.

Automated summary

Homodyne measurements are a commonly used quantum measurement method that limits to field quadrature measurement using a coherent state as the local oscillator. This paper presents a general idea that injecting nonclassical states as the local oscillator can lead to nonclassical measurements, with the specific example of injecting a superposition of coherent states, known as a Schrödinger cat state. The Kraus operators and positive operator-valued measure in this situation are derived.