Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

TL;DR

This study demonstrates the formation of ultracold heteronuclear 6Li40K* molecules via photoassociation, identifying rovibrational levels, measuring molecular properties, and estimating decay rates, thus advancing the creation of polar ground-state molecules for quantum applications.

Contribution

The paper reports the first detailed spectroscopic analysis of 6Li40K* molecules, including resonance identification, molecular constants, and formation rates, enabling future ultracold molecule production.

Findings

Over 60 rovibrational resonances identified

Molecule formation rates up to ~3.5x10^7 s^(-1)

Decay rates to ground state estimated at ~5x10^4 s^(-1)

Abstract

We investigate the formation of weakly bound, electronically excited, heteronuclear 6Li40K* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S_(1/2))+K(4P_(3/2)) and Li(2S_(1/2))+K(4P_(1/2)) asymptotic states and observed more than 60 resonances, which we identify as rovibrational levels of 7 of 8 attractive long-range molecular potentials. The long-range dispersion coefficients and rotational constants are derived. We find large molecule formation rates of up to ~3.5x10^7s^(-1), which are shown to be comparable to those for homonuclear 40K_2*. Using a theoretical model we infer decay rates to the deeply bound electronic ground-state vibrational level X^1\Sigma^+(v'=3) of ~5x10^4s^(-1). Our results pave the way for the production of ultracold bosonic ground-state 6Li40K molecules which exhibit a large intrinsic permanent electric dipole moment.