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Q: Fachverband Quantenoptik und Photonik

Q 29: Poster – Quantum Technologies I

Q 29.2: Poster

Dienstag, 3. März 2026, 17:00–19:00, Philo 2. OG

Towards Quantum Frequency Conversion of Single Photons from Germanium-Vacancy Centers in Diamond — •Jannis Sode, David Lindler, Marlon Schäfer, Tobias Bauer, Felix Rohe, and Christoph Becher — Universität des Saarlandes, Fachrichtung Physik, Campus E2 6, 66123 Saarbrücken

The germanium-vacancy (GeV) center in diamond is a promising candidate for a quantum memory in quantum communication networks due to its large Debye-Waller factor of up to 0.7 and long spin coherence times of more than 20 ms [1]. To facilitate the distribution of entanglement via preexisting optical fiber infrastructure, it is necessary to convert the single photons emitted by the GeV center from the visible spectrum into the low-loss telecom bands.
Here, we present our work towards low-noise, two-stage quantum frequency conversion of single photons resonant to germanium vacancy centers in diamond. The conversion scheme utilizes difference frequency generation in periodically poled lithium niobate waveguides to convert 602 nm photons to 867 nm, followed by a subsequent conversion to 1550 nm. Such a two-stage conversion scheme has been shown to achieve low conversion-induced noise for the conversion of silicon-vacancy centers [2]. We show first results on the conversion efficiency, as well as spectral noise distribution.

[1] K. Senkalla et al. Phys. Rev. Lett. 132, 026901, 2024
[2] M. Schäfer et al. Adv Quantum Technol. 2025, 8, 2300228

Keywords: quantum frequency conversion; quantum networks; nonlinear optics; quantum communication