Interference-Induced Quantum Squeezing Enhancement in a Two-beam Phase-Sensitive Amplifier

We experimentally demonstrate a method for realizing quantum squeezing enhancement which is induced by the interference in a two-beam phase-sensitive amplifier (PSA) based on a four-wave mixing process. Compared to the normal phase-insensitive amplifier with an intensity-difference squeezing (IDS) of $8.97\ifmmode\pm\else\textpm\fi{}0.24\text{ }\text{ }\mathrm{dB}$ or $8.76\ifmmode\pm\else\textpm\fi{}0.26\text{ }\text{ }\mathrm{dB}$, the IDS of our two-beam PSA is enhanced to $10.13\ifmmode\pm\else\textpm\fi{}0.21\text{ }\text{ }\mathrm{dB}$ under the same experimental situation. Furthermore, we study how various parameters influence the quantum squeezing enhancement of the PSA. These results clearly show that the physical mechanism inducing the IDS enhancement of the two-beam PSA is its intrinsic interference nature. Our results may find potential applications in improving the fidelity of quantum information processing and the precision of quantum metrology.