Quantum non-demolition measurement based on an SU(1,1)-SU(2)-concatenated atom-light hybrid interferometer

TL;DR

This paper proposes a novel SU(1,1)-SU(2)-concatenated atom-light hybrid interferometer for quantum non-demolition photon number measurement, demonstrating improved signal-to-noise ratio and potential for multiparameter quantum estimation.

Contribution

The paper introduces a new hybrid interferometer design combining SU(1,1) and SU(2) schemes for enhanced QND measurement performance and multiparameter estimation capabilities.

Findings

Improved SNR by a gain factor of the nonlinear Raman process.

Analysis of measurement quality under loss conditions.

Potential applications in quantum imaging and vector field detection.

Abstract

Quantum non-demolition (QND) measurement is an important tool in the field of quantum information processing and quantum optics. The atom-light hybrid interferometer is of great interest due to its combination of atomic spin wave and optical wave, which can be utilized for photon number QND measurement via the AC-Stark effect. In this paper, we present an SU(1,1)-SU(2)-concatenated atom-light hybrid interferometer, and theoretically study the QND measurement of photon number. Compared to the traditional SU(2) interferometer, the signal-to-noise ratio (SNR) in a balanced case is improved by a gain factor of the nonlinear Raman process (NRP) in this proposed interferometer. Furthermore, the condition of high-quality of QND measurement is analyzed. In the presence of losses, the measurement quality is reduced. We can adjust the gain parameter of the NRP in readout stage to reduce the impact due to losses. Moreover, this scheme is a multiarm interferometer, which has the potential of multiparameter estimation with many important applications in the detection of vector fields, quantum imaging and so on.