Comparative study of squeezed vacuum states prepared by using 1064-nm solid-state and fiber-laser as pump source
Yang Wen-Hai1, Diao Wen-Ting1, Cai Chun-Xiao1, Song Xue-Rui1, Feng Fu-Pan1, Zheng Yao-Hui2,3, Duan Chong-Di1
1. China Academy of Space Technology (Xi'an), Xi'an 710100, China;2. State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China;3. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China>
Squeezed states, which have fewer fluctuations in one quadrature than vacuum noise at the expense of increasing fluctuations in the other quadrature, can be used to enhance measurement accuracy, increase detection sensitivity, and improve fault tolerance performance for quantum information and quantum computation. In this paper, the influences of relative intensity noise (RIN) of all-solid-state single-frequency laser and single-frequency fiber laser on the squeezing factor of squeezed vacuum states are experimentally and theoretically studied. Here, an all-solid-state single-frequency laser and a single-frequency fiber laser each are used as a light source of the system generating squeezed vacuum states. The homodyne detection is used to compare the RIN of all-solid-state single-frequency laser and that of single-frequency fiber laser at the analysis frequency of 1 MHz. The results show that the RIN of the all-solid-state single-frequency laser and single-frequency fiber laser are higher than those of the shot noise limitation 2.3 dB and 30 dB at the analysis frequency of 1 MHz, respectively. The RIN of all-solid-state single-frequency laser is far less than that of the single-frequency fiber laser. As a result, squeezed vacuum state with maximum quantum noise reduction of (13.2 ±0.2) dB and (10 ±0.2) dB are directly detected. Theoretical calculation shows that the influence of the RIN on the measurement accuracy is the major factor of degrading the squeezing factor with the fiber laser as the pump source. The measurement error of squeezed vacuum state caused by the RIN of single-frequency fiber laser is about 2.6 dB. The discrepancy of the pump power between the two lasers is another factor of affecting the squeezing factor, corresponding to 0.6 dB quantum noise difference. The theoretical calculations are consistent with the experimental results, which provides some guidance for developing the practical squeezed states with highly squeezing level.
Project supported by the National Natural Science Foundation of China (Grant Nos. 11654002, 61575114, 61501368, 11505135), the Program for Sanjin Scholar of Shanxi Province, China, the Fund for Shanxi "1331 Project" Key Subjects Construction, China, and the Program for Outstanding Innovative Teams of Higher Learning Institutions of Shanxi, China.
Yang Wen-Hai, Diao Wen-Ting, Cai Chun-Xiao, Song Xue-Rui, Feng Fu-Pan, Zheng Yao-Hui, Duan Chong-Di. Comparative study of squeezed vacuum states prepared by using 1064-nm solid-state and fiber-laser as pump source[J]. Acta Phys. Sin., 2019, 68(12): 124201.