ShieldingΣ2ultracold dipolar molecular collisions with electric fields

Abstract

The prospects for shielding ultracold, paramagnetic, dipolar molecules from inelastic and chemical collisions are investigated. Molecules placed in their first rotationally excited states are found to exhibit effective long-range repulsion for applied electric fields above a certain critical value, as previously shown for non-paramagnetic molecules. This repulsion can safely allow the molecules to scatter while reducing the risk of inelastic or chemically reactive collisions. Several molecular species of 2 Σ molecules of experimental interest -RbSr, SrF, BaF, and YO -are considered, and all are shown to exhibit orders of magnitude suppression in quenching rates in a sufficiently strong laboratory electric field. It is further shown that, for these molecules described by Hund's coupling case b, electronic and nuclear spins play the role of spectator with respect to the shielding.

Coherent Microwave Control of UltracoldNa23K40Mole

“…Essentially all anticipated applications depend on the ability to coherently control the quantum state of molecules, implying full control over electronic, vibrational, rotational, and nuclear spin degrees of freedom [1]. With the recent production of dipolar molecules at submicrokelvin temperatures [9-13], this full quantum control has come into experimental reach for an entire ensemble of trapped molecules [14].Controlling the rotational states of molecules is directly linked to the control over long-range dipolar interactions [15][16][17][18][19][20][21]. Indeed, no state of definite parity can possess a dipole moment, but creating a superposition of oppositeparity rotational states induces one.…”

“…Controlling the rotational states of molecules is directly linked to the control over long-range dipolar interactions [15][16][17][18][19][20][21]. Indeed, no state of definite parity can possess a dipole moment, but creating a superposition of oppositeparity rotational states induces one.…”

Ultracold collisions of polyatomic molecules: CaOH

“…To emphasize this point, we have disregarded any possibility of chemical reactions, and perform scattering calculations assuming a hard wall boundary condition at R=30a 0 . We are guided here by the results of [25], where the long-range shielding due to an electrostatic field was shown to suppress chemical reactivity as well as long-range inelastic scattering. Going ahead, it will of course be valuable to incorporate the influence of any potential chemical reactivity, for example by means of absorbing boundary conditions [26,27].…”

“…Level repulsion ensures that the upper states rise in energy at smaller R where the dipole-dipole interaction grows in strength. This is the principle of electrostatic shielding [25,[30][31][32].…”

One-dimensional magneto-optical compression of a cold CaF molecular beam

“…Using the X v Av 0 0 = -¢ = ( ) ( )transition at 606 nm with a linewidth of 2 8.29MHz p´ [38], about 10 5 photons can be scattered with 2 vibrational repump lasers, before falling into higher vibrational states [43]. Recent theoretical work indicates that CaF is a good candidate for sympathetic/ evaporative cooling to reach temperatures in the microkelvin regime, a necessary step toward quantum degeneracy [41,42]. Once an ensemble of ultracold CaF molecules is prepared, its large electric dipole moment and spin degree of freedom will expand the Hamiltonians that can be simulated, including spin-lattice models [6].…”