Absolute sensitivity of phase measurement in an SU(1,1) type interferometer

TL;DR

This paper measures the absolute phase sensitivity of an SU(1,1) interferometer, demonstrating a 3dB improvement over a Mach-Zehnder interferometer, highlighting its potential for practical quantum sensing applications.

Contribution

It provides the first direct measurement of absolute phase sensitivity in an SU(1,1) interferometer and compares it to a Mach-Zehnder setup under identical conditions.

Findings

3dB sensitivity improvement over Mach-Zehnder interferometer

Successful phase locking at quantum noise cancellation point

Demonstration of direct phase estimation in nonlinear interferometry

Abstract

Absolute sensitivity is measured for the phase measurement in an SU(1,1) type interferometer and the results are compared to that of a Mach-Zehnder interferometer operated under the condition of the same intra-interferometer intensity. The interferometer is phase locked to a point with the largest quantum noise cancellation, and a simulated phase modulation is added in one arm of SU(1,1) interferometer. Both the signal and noise level are estimated at the same frequency range, and we obtain 3dB improvement in sensitivity for the SU(1,1) interferometer over the Mach-Zehnder interferometer. Our results demonstrate a direct phase estimation, and may pave the way for practical applications of nonlinear interferometer.