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Q: Fachverband Quantenoptik und Photonik

Q 28: Poster – Quantum Optics

Q 28.34: Poster

Tuesday, March 3, 2026, 17:00–19:00, Philo 2. OG

Sub-Doppler absorption lines at telecom wavelength in hot ⁸⁷Rb vapor — •Inna Kviatkovsky¹, Lucas Pache¹, Leonid Yatsenko², Viola-Antonella Zeilberger¹, Philipp Schneeweiss¹, Jürgen Volz¹, and Arno Rauschenbeutel¹ — ¹Department of Physics, Humboldt University of Berlin, Berlin, Germany — ²Institute of Physics, National Academy of Sciences of Ukraine, Kyiv, Ukraine

Room-temperature atomic ensembles for quantum technologies are gaining interest due to their accessibility and reduced experimental complexity. One of the main challenges when working with such ensembles is the Doppler-broadening of the atomic transition frequencies. In this work, we present an approach that mitigates Doppler broadening for the upper transition at telecom wavelength in a three-level ladder scheme in ⁸⁷Rb. The scheme involves driving the lower transition with a strong pump field at the D2-line wavelength of 780 nm, while a weak counter-propagating field at 1529 nm (5P_3/2→ 4D_5/2) probes the dressed state. We experimentally demonstrate that absorption features with sub-Doppler width and an enhanced optical depth can be achieved for the probe field. Moreover, the experimental spectra agree well with the predictions of our dedicated theory framework. Achieving sub-Doppler absorption lines together with high optical depth at the technologically relevant wavelength regime of the telecom C-band is highly relevant for applications in optical quantum technologies.

Keywords: Hot vapor; Doppler cancellations; Atomic ensembles