Tailored States for Optical Atomic Clocks

Optical atomic clocks represent the forefront of precision measurement, where quantum correlations and optimized interrogation strategies enable unprecedented frequency stability. In this talk, I will address laser-noise–limited regimes, where Bayesian frequency metrology provides a unified framework for incorporating frequency fluctuations and identifying optimal quantum states, measurement schemes, and estimation strategies. I will then consider regimes where clock stability is limited by spontaneous emission, and show that correlated measurements and nonlinear estimation strategies can achieve gains close to fundamental bounds. Surprisingly, in this regime it is GHZ-based protocols and – for larger ensembles of clock atoms – spin grid states similar to GKP spin states that provide optimal performance. Together, these results outline a comprehensive approach to tailoring quantum resources for next-generation optical atomic clocks.