Cold Atom Optics on Ground and in Space

Nassim Zahzam, Bruno Christophe, Alexandre Bresson +12 more

Lin Li, Qiuzhi Qu, Bin Wang +9 more

We report the initial test results of a rubidium ( 87 Rb) space cold atom clock (SCAC). The space-qualified 87 Rb SCAC is composed of the physical package, the optical bench, the microwave synthesizer and the control electronics. After the system is integrated, about 10 8 87 Rb cold atoms are captured by magneto-optical trap. The linewidth of the Ramsey fringe is about 10 Hz for the free evolution time of 50 ms on the ground, and the signal-to-noise ratio is measured to be larger than 300. We demonstrate a good medium-term fractional frequency stability of 1.5 × 10 −14 @1000 s in the closed-loop operation on the ground. The main effects of the noise on the stability are also presented, and the optimized operating parameter is analyzed for the operation of SCAC in the microgravity environment.

Naceur Gaaloul, Ernst Maria Rasel

Hui Li, Jiachen Yu, Xiaolong Yuan +15 more

The Cold Atom Physics Rack (CAPR) of Chinese space station will be launched at the end of 2022. The important goal of CAPR is to achieve BEC at 100 pk. In order to obtain ultracold atoms in microgravity of space station, we propose a two-stage cooling scheme using all-optical trap with different waist beams. The cold atom cloud obtained by this scheme is composed of condensate and thermal atoms around condensate. The design of our two-stage cooling scheme will effectively reduce the temperature of the thermal atom cloud and the effective temperature generated by the interaction energy of the condensate. The atomic temperature of 5 nk is obtained from the ground test experiment, and the corresponding temperature under the microgravity condition of the space station is theoretically predicted to be less than 100 pk. Taking the advantages of ultracold temperature and long-time detection, many scientific experiments will be arranged. In this paper, the ground test experiments based on ground principle prototype and pre-prototype for CAPR are also introduced.

Guglielmo Maria Tino

Kosuke Shibata, Hidehiko Ikeda, Ryota Suzuki +1 more

The authors demonstrate a simple optical technique to cancel gravity on a cold atom gas. Gravity often causes undesirable effects on cold atom experiments. While recent experiments in space enable liberation from gravity, the paper proposes to use a light field of a linear intensity profile produced by optical painting technique (rapid scanning of the beam position) to compensate for gravity on ultracold rubidium atoms in a standard laboratory. This optical levitation opens the possibilities for cold atom research in microgravity without any special setup and allows for precise measurements on the ground.