Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 41: Poster – Quantum Technologies II & Laser Technology

Q 41.6: Poster

Mittwoch, 4. März 2026, 17:00–19:00, Philo 2. OG

Highly-efficient, low noise quantum frequency conversion of single photons from a tin-vacancy center in diamond — •Marlon Schäfer, David Lindler, Tobias Bauer, and Christoph Becher — Universität des Saarlandes, Campus E2 6, 66123 Saarbrücken

Quantum frequency conversion (QFC) is a key enabling technology for quantum repeaters and large-scale quantum networks, as it connects quantum memories with optical transitions in the visible and near-infrared spectrum to the low-loss telecommunication bands used in optical fiber networks. Here, we demonstrate a highly efficient and low-noise QFC device for single photons resonant with tin-vacancy (SnV) centers in diamond. Using difference-frequency generation in periodically poled lithium niobate waveguides, single photons at 619 nm are mixed with a strong 2062 nm pump beam to generate light at an intermediate wavelength of 885 nm, followed by a second conversion stage to 1550 nm. This two-step conversion scheme strongly suppresses noise from pump-induced spontaneous parametric processes as well as Raman scattering, resulting in an exceptionally low noise level of less than 4 photons per second per gigahertz of filter bandwidth. In addition, the device achieves a fiber-to-fiber conversion efficiency of 45%, including an 8 GHz bandwidth filtering stage. Measurements of second-order correlation functions for the converted photons confirm the preservation of nonclassical photon statistics after frequency conversion.

Keywords: quantum frequency conversion; difference frequency generation; nonlinear optics; silicon-vacany center