Enhancement in phase sensitivity in displacement-assisted SU(1,1) interferometer via photon recycling

We propose a novel method for enhancing phase estimation in the displacement-assisted SU(1,1) [DSU(1,1)] interferometer by incorporating the photon recycling technique, evaluated under both single-intensity detection (SID) and homodyne detection (HD) schemes. Our analysis shows that utilizing the photon recycling technique, the photon-recycled DSU(1,1) interferometer performs better than the conventional DSU(1,1) interferometer under certain conditions. We also demonstrate that this improvement is achievable in both SID and HD schemes. In addition, to discuss the maximum sensitivity achieved by our proposed model, we have calculated the quantum Cramér–Rao bound (QCRB) within the framework and found that our proposed model approaches the QCRB. Therefore, we believe that our findings offer a promising new approach to improving phase sensitivity through photon recycling.