Optical Cycling and Sensitivity to the Electron's Electric Dipole Moment in Gold-Containing Molecules

Abstract: We propose diatomic molecules built from gold and carbon-group atoms as promising candidates for optical cycling and precision measurements. We show that this class of molecules (AuX, X = C, Si, Ge, Sn, Pb) features laser-accessible electronic transitions with nearly diagonal Franck-Condon factors. The $^2\Pi_{1/2}$ ground states can be easily polarized in the laboratory frame and have near-zero magnetic moments, valuable features for quantum science and precision measurement applications. The sensitivities of AuX molecules to the electron electric dipole moment (EDM) are found to be favorable, with effective electric fields of 10-30 GV/cm. Together, these features imply that AuX molecules may enable significantly improved searches for time-reversal symmetry violation.