Realizing a Bose-Einstein condensate of polar molecules
Abstract
We propose experiments aimed at producing the first-ever Bose-Einstein condensate(BEC) of polar molecules. A BEC of polar molecules would represent a new regime in the physicsof quantum-degenerate gases, opening a path to a vast range of new experiments enabled by thestrong, long-range, and controllable electric-dipole interactions between molecules. In addition,observation and characterization of ultracold atom-molecule and molecule-molecule collisionalproperties along the path to BEC will be of substantial scientific interest in its own right. A widerange of proposals exist to employ such a quantum-degenerate gas of polar molecules inapplications including quantum information, novel sensors, and fundamental physics; as such,development of a BEC of polar molecules is likely to enhance future DoD capabilities.Our planned experiments build on our recent work demonstrating a magneto-optical trap(MOT) of strontium monofluoride (SrF) molecules, most recently delivering a sample of ~10,000molecules at temperatures as low as 250 microKelvin and with density exceeding 100,000 percubic cm. This is a sufficiently large, cold, and dense sample from which to create a BEC. Weplan to co-trap of samples of SrF with Rb-87 atoms, which easily can be cooled to form a BEC oftheir own. The ultracold Rb atom cloud will be used to sympathetically cool SrF, by thermalequilibration, until the density of trapped SrF is sufficiently high that it begins to undergocollisional losses (for example, due to SrF chemically reacting with itself). If this occurs beforeBEC is achieved, we plan to protect SrF from reactions and other destructive collisions byengineering purely long-range, strongly repulsive interactions between the molecules. This can beachieved by applying an electric field to molecules in a long-lived excited quantum state, such thatthe usually attractive van der Waals forces become repulsive. The molecules can then be cooledfurther, towards quantum degeneracy, via the technique of forced evaporation. Together, thesesteps should make it possible to create the conditions needed for a BEC of SrF. The properties ofSrF that make it possible to create a MOT also allow use of the same detection techniques as instandard atomic experiments using BECs. We will probe the molecular condensate with thecommonly-used time-of-flight and absorption imaging methods. The techniques proposed hereapply proven methods from atomic physics, and extending their application to molecules couldprovide a revolutionary tool for the production of large samples of ultracold polar molecules forfuture studies.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2017
- Source ID
- N000141712250
Entities
People
- David DeMille
Organizations
- Office of Naval Research
- United States Navy
- Yale University