Quantum optics of small systems

Yongda Li, Ke Shen, Liqun Huang +1 more

A theoretical investigation has been undertaken to study the amplification of small-signal by an acousto-optic bistable system operating in the Bragg regime. Numerical solutions of the difference-differential equation show strong coupling between small-signal and the optical bistable system. Near the bifurcation point an amplification of 23 is obtained. computed time plots for different parameters and the beat characteristic curve are given.

H. J. Carmichael, Roy J. Glauber, Marlan O. Scully

Haosen Shang, Xiaogang Zhang, Shengnan Zhang +2 more

In this paper a small Calcium beam optical frequency standard utilizing fully-sealed Calcium beam vacuum tube owning smaller size compared with vacuum system with flanges is demonstrated. Adopting the electron shelving detection method, we detect the clock transition 657 nm saturation absorbing spectroscopy whose linewidth is 500 kHz. The instability of this small optical frequency standard is 6.8×10-14at 1 second and 1.8×10-15after 1000 seconds of averaging by comparing with another small Calcium beam optical frequency standard whose reported instability is 3.0×10-14at 1 second. The optical part of the whole system is specially designed for robustness and miniaturization.

H. J. Carmichael, Roy J. Glauber, Marlan O. Scully

M. Ducloy, Daniel Bloch

Chengxiang Tu, Jiayi Shen, Jiansheng Dai +2 more

The features of unmanned aerial vehicles (UAVs), such as strong manoeuvrability, small size, and light weight, make them considered to participate in free space optical (FSO) quantum communication, becoming an important part of the Space-Air-Ground Integrated Network. However, research reports on small-sized drones based long-range optical quantum link are few. A major challenge is that traditional opto-mechanical structure is difficult to adapt to small UAV platforms. Here, a lower size, weight, and power (SWaP) acquisition and tracking system prototype is developed, and its greatest advantage is that the system can be easily integrated into small flying platforms and quickly build a long-distance quantum communication link. The prototype weighs less than 8 kg. A small-sized two-axis mirror mechanism is designed for wide-range acquisition and tracking. Moreover, the system can automatically point to ground station. The SWaP acquisition and tracking system can support quantum key distribution (QKD) link and general FSO link by drones. In the 7 km air-to-ground demonstration, the acquisition and tracking system prototype is tested in practice, which is suspended under the small six-rotor UAV platform, and a special passive vibration isolation unit is added in between. A ten-minute continuous and stable beacon tracking proves that the system can quickly and automatically align.