Phase sensitivity for an SU(1,1) interferometer via multiphoton subtraction at the output port

TL;DR

This paper theoretically demonstrates that multiphoton subtraction at the output of an SU(1,1) interferometer enhances phase sensitivity and quantum Fisher information, even under photon loss, surpassing standard quantum limits.

Contribution

It introduces a novel approach of multiphoton subtraction to improve phase sensitivity in SU(1,1) interferometers under realistic loss conditions.

Findings

Multiphoton subtraction increases phase sensitivity and quantum Fisher information.

Internal photon loss impacts phase sensitivity more than external loss.

Phase sensitivity can surpass the standard quantum limit even with severe photon loss.

Abstract

In the field of quantum precision measurement, enhancing phase sensitivity is crucial for various applications, including quantum metrology and quantum sensing technologies. We theoretically investigate the improvement in phase sensitivity and quantum Fisher information achieved through multiphoton subtraction operations at the output port of an SU(1,1) interferometer under conditions of photon loss. We use vacuum and coherent states as the inputs and detect the outputs by intensity detection. The results indicate that internal photon losses within the SU(1,1) interferometer have a more significant impact on the phase sensitivity compared to external photon losses. Moreover, increasing the number of photon subtractions m effectively enhances both the phase sensitivity and the quantum Fisher information. Notably, even under conditions of severe photon loss, the multiphoton subtraction operations can enable the phase sensitivity to surpass the standard quantum limit, approaching both the Heisenberg limit and the quantum Cram\'er-Rao bound. This study provides a new theoretical basis for enhancing the phase sensitivity in the SU(1,1) interferometer.