Metrological prospects for ultracold $^{88}{Sr}_2$ molecules in the absolute rovibrational ground state

We report on the successful creation of an ultracold sample of ground-state $^{88}{Sr}_2$ molecules. This demonstrates important progress toward an ultracold strontium molecular clock for metrology and precision measurements. Molecules are transferred from the most-weakly bound vibrational level of the ground potential to the absolute ground state via low-lying vibrational states in the $(1)0_{u}^{+}$ excited state using a counterintuitive STIRAP pulse scheme. In addition, we have identified prospective far-off-resonant “magic” lattice wavelengths in the mid-IR, - wavelengths for which the differential polarizability between two clock states vanishes. These potential magic values occur for deeply bound ground rovibrational states and offer attractive prospects for long-lived coherent superpositions of clock states for the study of variations of fundamental constants and fifth-force measurements.