Submillikelvin Dipolar Molecules in a Radio-Frequency Magneto-Optical Trap

Abstract

We demonstrate a scheme for magneto-optically trapping strontium monofluoride (SrF) molecules at temperatures one order of magnitude lower and phase space densities 3 orders of magnitude higher than obtained previously with laser-cooled molecules. In our trap, optical dark states are destabilized by rapidly and synchronously reversing the trapping laser polarizations and the applied magnetic field gradient. The number of molecules and trap lifetime are also significantly improved from previous work by loading the trap with high laser power and then reducing the power for long-term trapping. With this procedure, temperatures as low as 400 μK are achieved.

Cold collisions of heavy Σ2 molecules with alkali-metal atoms in a magnetic field: Ab initio analysis and prospects for sympathetic cooling of SrOH(Morita1, Kłos2, Buchachenko3 et al. 2017Phys. Rev. A252441View full textAdd to dashboardCite

“…At present, coherent association of ultracold alkali-metal atoms remains the only experimental technique to produce ultracold gases of polar molecules KRb and NaK [11][12][13]. Recent advances in laser cooling and magneto-optical trapping [14][15][16][17][18], single-photon cooling [19], Sisyphus laser cooling [20,21], and optoelectrical cooling [21,22] made it possible to control and confine molecular species such as SrF, CaF, SrOH, YO, CH 3 F, and H 2 CO in electrostatic and magnetic traps at temperatures as low as a fraction of a milliKelvin [14-19, 21, 22]. Due to the intrinsic limitations of optical cooling, it is necessary to employ second-stage cooling techniques to further reduce the temperature of a trapped molecular gas to <0.1 mK [1,19].…”

“…[34] for a detailed discussion). As a result, it remains unclear whether heavy molecular radicals trapped in recent experiments [14][15][16][17][18][19] have small enough inelastic collision rates with ultracold alkali-metal atoms to allow for efficient sympathetic cooling in a magnetic trap.…”

New frontiers for quantum gases of polar molecules

“…For example, the current state-of-the-art for the molecular magneto-optical trap (MOT) [27,28,29] is about 2000 molecules of SrF at ∼ 400 µK [30], corresponding to a phase-space density orders of magnitude smaller than typical atomic alkali MOTs of 10 9 −10 10 atoms at ∼ 10 µK. Many other techniques have also been employed to create cold molecules, such as photoassociation [31], buffer gas cooling [32], Stark deceleration [33,34], and Sisyphus cooling [35]; however, the achieved phase-space densities are all very far from that required for quantum degeneracy.…”

Electric dipole moments of superheavy elements: A case study on copernicium

“…The advantage of molecular eEDM experiments is in the large values of the effective electric field, several orders of magnitude higher than those in atoms [17,18,87,88]. Current progress in cooling and trapping molecules [89][90][91][92][93], as well as molecular ions [94,95], may soon allow one to increase coherence times and improve population control in molecular experiments, which might translate into a significant advantage of molecular experiments over atomic ones.…”