Abstract
We present experimental results from a new scheme for magneto–optically trapping strontium monofluoride (SrF) molecules, which provides increased confinement compared to our original work. The improved trap employs a new approach to magneto–optical trapping presented by Tarbutt (2015 New J. Phys. 17 015007), which provided insight for the first time into the source of the restoring force in magneto–optical traps (MOTs) where the cycling transition includes dark Zeeman sublevels (known as type-II MOTs). We measure a radial spring constant greater than in our original work with SrF, comparable to the spring constants reported in atomic type-II MOTs. We achieve a trap lifetime ms, over longer than originally reported for SrF. Finally, we demonstrate further cooling of the trapped molecules by briefly increasing the trapping lasers’ detunings. Our trapping scheme remains a straightforward extension of atomic techniques and marks a step towards the direct production of large, dense, ultracold molecular gases via laser cooling.
Highlights
Over the last decade there has been significant and growing interest in the production and manipulation of samples of cold and ultracold polar molecules [1]
The increased magneto-optical confinement of a diatomic molecule presented in this work is in good qualitative agreement with recent numerical simulations and physical arguments presented in ref
The trapping scheme used in this magneto-optical traps (MOTs) provides tighter confinement than could be achieved with our original configuration, with spring constants comparable to those reported in atomic type-II MOTs [20]
Summary
Over the last decade there has been significant and growing interest in the production and manipulation of samples of cold and ultracold polar molecules [1]. Laser cooling and trapping have revolutionized atomic physics, and their maturity and effectiveness for certain atoms may be viewed as the reason indirect methods of molecule production are currently able to attain higher phase-space densities than direct methods. The workhorse technique in cold-atom physics is the magneto-optical trap (MOT), which combines a restoring force from radiation pressure with laser cooling [14]. In this work we present an improved SrF MOT This new MOT uses a trapping scheme proposed by M. We introduce the basic types of MOT, highlight why the source of the restoring force in type-II MOTs was not well understood, and outline the new approach to magneto-optical trapping for type-II systems implemented in this work
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