Controlling the Rotational and Hyperfine State of Ultracold $^{87}$Rb$^{133}$Cs Molecules

TL;DR

This paper demonstrates precise microwave control of rotational and hyperfine states in ultracold $^{87}$Rb$^{133}$Cs molecules, enabling state manipulation for quantum applications.

Contribution

It introduces a method for coherent control of hyperfine and rotational states in ultracold molecules with high precision and demonstrates population transfer between states.

Findings

Measured transition frequencies to hyperfine levels with high accuracy.

Observed Rabi oscillations enabling complete population transfer.

Determined hyperfine coupling constants consistent with previous models.

Abstract

We demonstrate coherent control of both the rotational and hyperfine state of ultracold, chemically stable $^{87}$Rb$^{133}$Cs 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 8 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 transfer of molecules back to a different hyperfine level of N = 0.