Coherent Manipulation of the Internal State of Ultracold $^{87}$Rb$^{133}$Cs Molecules with Multiple Microwave Fields

TL;DR

This paper demonstrates coherent control of ultracold $^{87}$Rb$^{133}$Cs molecules using multiple microwave fields, achieving long coherence times, state dressing, and detailed spectroscopy, advancing their use in quantum information and simulation.

Contribution

It introduces new methods for manipulating ultracold molecules with microwave fields, including two-photon Raman transitions, Autler-Townes doublets, and precise rotational spectroscopy.

Findings

Achieved a Ramsey coherence time of 58 ms for hyperfine superpositions.

Controlled microwave dressing of molecular states via varying field intensity.

Performed rotational spectroscopy up to N=6, determining a new centrifugal distortion coefficient.

Abstract

We explore coherent multi-photon processes in $^{87}$Rb$^{133}$Cs molecules using 3-level lambda and ladder configurations of rotational and hyperfine states, and discuss their relevance to future applications in quantum computation and quantum simulation. In the lambda configuration, we demonstrate the driving of population between two hyperfine levels of the rotational ground state via a two-photon Raman transition. Such pairs of states may be used in the future as a quantum memory, and we measure a Ramsey coherence time for a superposition of these states of 58(9) ms. In the ladder configuration, we show that we can generate and coherently populate microwave dressed states via the observation of an Autler-Townes doublet. We demonstrate that we can control the strength of this dressing by varying the intensity of the microwave coupling field. Finally, we perform spectroscopy of the rotational states of $^{87}$Rb$^{133}$Cs up to $N=6$, highlighting the potential of ultracold molecules for quantum simulation in synthetic dimensions. By fitting the measured transition frequencies we determine a new value of the centrifugal distortion coefficient $D_v=h\times207.3(2)~$Hz.