Controlling the rotational and hyperfine state of ultracold Rb 87 Cs 133 molecules

Abstract

We demonstrate coherent control of the rotational and hyperfine state of ultracold, chemically stable Rb87Cs133 molecules with external microwave fields. We create a sample of ∼2000 molecules in the lowest hyperfine level of the rovibronic ground state N=0. We measure the transition frequencies to eight different hyperfine levels of the N=1 state at two magnetic fields ∼23 G apart. We determine accurate values of rotational and hyperfine coupling constants that agree well with previous calculations. We observe Rabi oscillations on each transition, allowing complete population transfer to a selected hyperfine level of N=1. Subsequent application of a second microwave pulse allows the transfer of molecules back to a different hyperfine level of N=0.