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Q: Fachverband Quantenoptik und Photonik

Q 53: Precision Spectroscopy of Atoms and Ions IV (joint session A/Q)

Q 53.3: Vortrag

Donnerstag, 5. März 2026, 11:45–12:00, N 3

Spin noise spectroscopy of hot rubidium vapor under two-photon excitation — •Oskar Sund and Ilja Gerhardt — light and matter group, Institute for Solid State Physics, Leibniz University Hannover, Appelstrasse 2,D-30167 Hannover, Germany

Doppler free realized S-P-D transitions in hot rubidium vapor have emerged as a promising contender as stable, compact and low-cost frequency references, potentially superseding the chip-scale atomic clocks of today. Unlike the conventional approach of the two-photon excitation in rubidium at 778.1 nm, a two-color approach would require significantly lower optical powers and vapor densities while achieving comparable frequency stability [1]. In this work, we present two-color, two-beam spin noise spectroscopy: one laser (780 nm) probes ground-state spin fluctuations, while a second laser (776 nm) completes the 5S-5D ladder-type two-photon transition. By measuring the spin noise on both beams, as well as their noise correlation, we investigate how the two-photon excitation perturbs ground-state spin dynamics and whether additional spin noise features or dynamic back-action from excited states can be observed. Such measurements provide new insights into nonlinear spin-light interactions, potentially relevant for precision metrology, quantum sensing and future frequency standards.

[1] Ahern, E. J., Scholten, S. K., Locke, C. et al. Tailoring the stability of a two-color, two-photon rubidium frequency standard. Phys. Rev. Applied 23, 044025 (2025)

Keywords: rubidium vapor; spin noise; nonlinear spectroscopy