Inelastic losses in radio-frequency-dressed traps for ultracold atoms

Abstract

(2017) 'Inelastic losses in radio-frequency-dressed traps for ultracold atoms. ', Physical review A., 96 (4). 042707.Further information on publisher's website:https://doi.org/10.1103/PhysRevA.96.042707Publisher's copyright statement:Reprinted with permission from the American Physical Society: Owens, Daniel J. Hutson, Jeremy M. (2017). Inelastic losses in radio-frequency-dressed traps for ultracold atoms. Physical Review A 96(4): 042707 c 2017 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modi ed, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We calculate the rates of inelastic collisions for ultracold alkali-metal atoms in radio-frequency-dressed traps, using coupled-channel scattering calculations on accurate potential energy surfaces. We identify a radiofrequency-induced loss mechanism that does not exist in the absence of radio frequency (rf) radiation. This mechanism is not suppressed by a centrifugal barrier in the outgoing channel, and can be much faster than spin relaxation, which is centrifugally suppressed. We explore the dependence of the rf-induced loss rate on singlet and triplet scattering lengths, hyperfine splittings, and the strength of the rf field. We interpret the results in terms of an adiabatic model of the collision dynamics, and calculate the corresponding nonadiabatic couplings. The loss rate can vary by 10 orders of magnitude as a function of singlet and triplet scattering lengths. 87 Rb is a special case, where several factors combine to reduce rf-induced losses; as a result, they are slow compared to spin-relaxation losses. For most other alkali-metal pairs, rf-induced losses are expected to be much faster and may dominate.

Microwave Shielding of Ultracold Polar Molecules

“…We also consider 40 Ca 19 F( 2 Σ + ) molecules in this work. In this case, the 19 F nucleus and the electrons contribute 1/2 spin, while 40 Ca has zero nuclear spin. The couplings involving the electron spin have a similar form as discussed above for the hyperfine interactions of 1 Σ molecules, but the coupling constants are typically much larger, as can be seen in Table I.…”

Realising a species-selective double well with multiple-radiofrequency-dressed potentials

“…The species-selective manipulations we have demonstrated are only of practical use if the mixture does not suffer large inelastic losses. Recent work concerning a mixture of 85 Rb and 87 Rb indicates that most RF-dressed mixtures are expected to undergo fast inelastic loss [38]; the atom-photon coupling allows inelastic collisions to conserve angular momentum through absorption or emission of an RF photon, allowing spin exchange to occur with large rate coefficients [38,41]. Fortunately, for collisions of 87 Rb atoms, the rate coefficients for spin exchange are small, and it proceeds slowly even for cases that are allowed by angular momentum conservation rules.…”

“…Exploiting this feature, we implement a species-selective double well using MRF-dressed potentials and manipulate the spatial distribution of the individual mixture constituents. Recent theoretical [41] and experimental [38] studies have shown that not all mixtures are collisionally stable when confined in RF-dressed potentials. In this work, we demonstrate the merit of an RF-dressed mixture of 87 Rb F = 1 and F = 2, which we find to be long-lived.…”

Microwave shielding of ultracold polar molecules with imperfectly circular polarization

“…For the colliding pair of molecules we introduce an angular momentum state, |LM L , that describes the end-overend rotation of the intermolecular axis. The basis functions for the pair of molecules are [25][26][27]…”