Quantum metrology with parametric amplifier-based photon correlation interferometers

TLDR

Conventional interferometers use beam splitters for wave splitting and recombination, are widely employed for precision measurement, yet their phase sensitivity is limited by shot noise, which can be suppressed with squeezed states of light. The study aims to investigate a parametric amplifier‑based interferometer that replaces conventional beam splitters with parametric amplifiers. The interferometer employs parametric amplifiers for beam splitting and recombination. The device achieves a 4.1 ± 0.3 dB improvement in signal‑to‑noise ratio, a 1.6‑fold enhancement in rms phase sensitivity beyond the shot‑noise limit, and, when combined with squeezed‑state techniques, promises further gains and enables hybrid interferometers for diverse metrology applications.

Abstract

Conventional interferometers usually utilize beam splitters for wave splitting and recombination. These interferometers are widely used for precision measurement. Their sensitivity for phase measurement is limited by the shot noise, which can be suppressed with squeezed states of light. Here we study a new type of interferometer in which the beam splitting and recombination elements are parametric amplifiers. We observe an improvement of 4.1±0.3 dB in signal-to-noise ratio compared with a conventional interferometer under the same operating condition, which is a 1.6-fold enhancement in rms phase measurement sensitivity beyond the shot noise limit. The improvement is due to signal enhancement. Combined with the squeezed state technique for shot noise suppression, this interferometer promises further improvement in sensitivity. Furthermore, because nonlinear processes are involved in this interferometer, we can couple a variety of different waves and form new types of hybrid interferometers, opening a door for many applications in metrology.