An application of the measurement of expectation values for the photon annihilation and creation operators

TL;DR

This paper explores a measurement scheme called double balanced homodyne detection for assessing expectation values of photon operators, with potential applications in gravitational-wave detector readouts.

Contribution

It introduces and evaluates a novel measurement method for photon expectation values, connecting it to existing eight-port homodyne detection techniques.

Findings

Identifies the measurement scheme as a rediscovery of eight-port homodyne detection.

Evaluates the noise spectral density associated with the measurement.

Discusses potential applications in gravitational-wave detector readout schemes.

Abstract

Motivated by the readout scheme in interferometric gravitational-wave detectors, we consider the device which measures the expectation value of the photon annihilation and creation operators for output optical field from the main interferometer. As the result, the eight-port homodyne detection is rediscovered as such a device. We evaluate the noise spectral density in this measurement. We also briefly discuss on the application of our results to the readout scheme of gravitational-wave detectors. We call this measurement scheme to measure these expectation values as "double balanced homodyne detection."