Laser cooling to quantum degeneracy1

Yvan Castin, Jean Dalibard

S. V. Petrushkin, В. В. Самарцев

Laser cooling is an important emerging technology in such areas as the cooling of semiconductors. The book examines and suggests solutions for a range of problems in the development of miniature solid-state laser refrigerators, self-cooling solid-state lasers and optical echo-processors. It begins by looking at the basic theory of laser cooling before considering such topics as self-cooling of active elements of solid-state lasers, laser cooling of solid-state information media of optical echo-processors, and problems of cooling solid-state quantum processors. Laser Cooling of Solids is an important contribution to the development of compact laser-powered cryogenic refrigerators, both for the academic community and those in the microelectronics and other industries. Provides a timely review of this promising field of research and discusses the fundamentals and theory of laser cooling Particular attention is given to the physics of cooling processes and the mathematical description of these processes Reviews previous experimental investigations in laser cooling and presents progress towards key potential applications.

Yvan Castin, Kirstine Berg‐Sørensen, Klaus Mølmer +1 more

Xin Wang, Yuan Sun, Liang Liu

Quantum sensing with cold atoms is attracting more and more attention in the research frontier of quantum technologies. Isotropic laser cooling serves as a promising platform for this area and its many advantages include compactness, robustness, and not requiring fine-tuning of the optical alignment or magnetic field, which are particularly suitable for field and space applications. We have designed and demonstrated a special form of isotropic laser cooling system that is specifically tailored for the purpose of quantum sensing. In particular, the diffused cooling optical field is generated by hollow laser beam injection and the quality of detection process is improved. Moreover, the effective strength of diffused cooling laser is quantitatively deduced. We have carefully characterized the properties of our system, including the laser cooling performances with respect to different parameter settings, the influences of cooling laser polarization and repumping laser power, and radial atom density distribution. We anticipate that our progress will contribute to the future development of isotropic laser cooling for quantum sensing and quantum precision measurements.

Hidekazu Hachisu

DU Guo-tong

The main problem in laser cooling investigation is to choose materials. One of the keys is the energy width split out between ground state and excited state of luminescence center. Choosing the energy space reasonably will help us to determine laser-cooling media correctly. The energy gap of two states determines two important elements in laser cooling, quantum efficiency and multiphonon relaxation rate. Only as for cooling power in laser cooling, the more the energy gap splits, the higher quantum efficiency is and the more powerful is to fluorescent cooling. When the energy gap reaches a certain width or more, the cooling power will almost keep unchanging. If heat-light converting efficiency is considered in laser cooling, the energy gap in reason should be much narrower. If we confirm that it is the most important to keep cooling power at the highest level, then, it is more appropriate to choose the energy gap at 5000cm-l than 10 000cm-l of Yb3+, because, the choosing can not only confirm higher heat-light converting efficiency, but also ensure in substance a high cooling power.