Laser-cooling molecules

Valentina Zhelyazkova, Aki Matsushima

Timur A. Isaev

Abstract The methods of laser cooling of atoms have long been applied to obtain cold and ultracold atomic gases, including degenerate states and the atomic Bose–Einstein condensate in particular. Until recently the application of laser cooling methods to molecules was assumed to be impossible because of the complex structure of molecular levels and the absence of closed cooling cycles for transitions between the electron levels of molecules in the general case. However, it has recently become clear that laser cooling can be performed for a large class of molecules, including not only the simplest diatomic molecules but also polyatomic molecules. We here present the general principles for identifying suitable molecules and discuss current studies on and further developments in the laser cooling of molecules.

P. Yzombard, M. Hamamda, S. Gerber +2 more

We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.

Noah J. Fitch, Michael R. Tarbutt

Adela Marian, Břetislav Friedrich

A Sisyphean task: Laser cooling of molecules is difficult, mainly due to their rich vibrational structure, typically requiring dozens of repumping lasers. However, a proof-of-principle experiment to laser cool SrF molecules has been done (see picture), showing that laser cooling of some molecules is possible with just three lasers, as Highlighted herein.

P. Pillet, Matthieu Viteau, Amodsen Chotia +5 more