Exponential enhancement of sensitivity in Ramsey interferometry with optically thick ensemble of atoms

Abstract:Ramsey interferometry is a cornerstone technique for precise measurement of time and frequency in modern clocks. The Ramsey experiments are typically done in optically dilute samples of atoms to improve homogeneity and avoid back-action of atoms on excitation pulses. In contrast to later belief, we predict and experimentally show that in optically thick samples with inhomogeneous broadening of resonant transition, the back-action can lead to the highly enhanced narrowing of Ramsey resonance. The linewidth narrowing and corresponding precision of the frequency measurement scale exponentially with an increase in optical depth of a sample and can reach the limits set by homogeneous broadening. We show that this effect is caused by a nonlinear interference of multiple echoes formed inside the atomic medium, which is experimentally confirmed with $^{167}\text{Er}^{3+}$ ions in $\text{Y}_2\text{SiO}_5$ crystal. Our findings open new opportunities for nonlinear high-resolution spectroscopy of resonant media and sensitivity enhancement in a new generation of solid state clocks.

Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph); Optics (physics.optics)

arXiv:2505.13146 [quant-ph]

(or arXiv:2505.13146v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2505.13146 Focus to learn more arXiv-issued DOI via DataCite

Moiseev, S. A., Gerasimov, K. I., Minnegaliev, M. M., Brekotkin, I. V., & Moiseev, E. S. Phys. Rev. Lett. 137(2), 023603 (2026)

https://doi.org/10.1103/bqzh-gy4n Focus to learn more DOI(s) linking to related resources

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