Terahertz Vibrational Molecular Clock

This chapter details the marriage of molecular quantum science with atomic clock-making, resulting in an accurate clock based solely on the vibrational transitions of a molecule. I describe the molecular magic wavelength protocol and discuss its impact on the vibrational coherence time. Next, I outline the clock architecture and enumerate all known perturbations to the clock transition. Facilitated by the narrow molecular clock linewidth, hertz-level frequency shifts were resolved, enabling the evaluation of the clock’s systematic uncertainty at the 14th decimal place in fractional units. I report the measurement of the molecular clock transition frequency, which may inspire molecule-based secondary representations of the SI unit of time in the terahertz (THz) band where standards are scarce. This vibrational splitting, in turn, allows the dissociation energy of the dimer to be determined with high precision and accuracy. The molecular lattice clock lays the critical groundwork for future explorations into THz metrology, quantum chemistry, and fundamental interactions at atomic length scales.