Deceleration of molecules by dipole force potential: a numerical simulation

We propose a new method for making ultracold molecules below 300 μK by cooling via the dipole force of an intense infrared (IR) standing wave created in a high finesse cavity. Deceleration can be achieved by periodically switching an IR standing wave slightly red-detuned from the resonance frequency of a molecular vibration–rotation transition. The potential depth becomes as high as 50 mK with an incident laser power of 3 W. By properly switching the potential, one can remove the translational energy of molecules from a couple of hundred mK to 300 μK or below. Since all molecules except homonuclear diatomic molecules have one or more optical transitions in the IR range that can be used for a source of the dipole force, the present method is applicable to almost all molecules of chemical interest. Moreover, by choosing an appropriate rotation–vibration transition, one can decelerate and trap molecules in the completely ground state in any degrees of freedom. Numerical simulations showed sufficiently wide phase-space areas of decelerated molecules through use of this technique for practical applications. The effect of various parameters on the efficiency of the cavity decelerator has been examined by numerical simulations.