Observation of Ultracold Ground-State Potassium Molecules

Abstract

Ultracold potassium molecules are produced in the $X{}_{}{}^1{}_{}{}^{}\Sigma _g^{+}{}_{}{}^{}$ electronic ground state by photoassociation in a magneto-optical trap. They are detected sensitively and selectively by use of two-color resonant ionization, followed by time-of-flight mass spectroscopy. We observe deeply bound molecules with $\nu \cong 36$, at a temperature of about $300\mu \mathrm{K}$. Presently about 1000 molecules/sec are produced, and much higher production rates should be attainable in the future.