Parity Detection in Quantum Optical Metrology Without Number Resolving Detectors

TL;DR

This paper introduces a practical method to detect the parity of Gaussian states in quantum optical metrology using simple homodyne and intensity correlation techniques, avoiding complex photon-number resolving detectors.

Contribution

The authors propose a novel parity detection scheme that does not require photon-number resolving detectors, enabling easier implementation in quantum interferometry with coherent or squeezed light.

Findings

Parity can be measured without photon-number resolving detectors.

The method works for arbitrary photon flux in interferometric setups.

The 'parity-by-proxy' measurement yields the same signal as traditional parity detection.

Abstract

We present a method of directly obtaining the parity of a Gaussian state of light without recourse to photon-number counting. The scheme uses only a simple balanced homodyne technique, and intensity correlation. Thus interferometric schemes utilizing coherent or squeezed light, and parity detection may be practically implemented for an arbitrary photon flux. Specifically we investigate a two-mode, squeezed-light, Mach-Zehnder interferometer and show how the parity of the output state may be obtained. We also show that the detection may be described independent of the parity operator, and that this "parity-by-proxy" measurement has the same signal as traditional parity.