Quantum 2025 – scientific programme
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MON: Monday Contributed Sessions
MON 2: Quantum Control
MON 2.7: Talk
Monday, September 8, 2025, 15:45–16:00, ZHG002
Spectral Control of a Noisy Quantum Emitter with Optical Pulses — •Kilian Unterguggenberger1, Alok Gokhale1, Aleksei Tsarapkin1,2, Wentao Zhang2, Katja Höflich1,2, Herbert Fotso3, Tommaso Pregnolato1,2, Laura Orphal-Kobin1, and Tim Schröder1,2 — 1Humboldt-Universität zu Berlin, Germany — 2Ferdinand-Braun-Institut (FBH), Berlin, Germany — 3University at Buffalo SUNY, Buffalo, USA
Indistinguishability of single photons gives rise to quantum interference, making it an essential ingredient for quantum information processing. Optimizing single-photon sources for indistinguishability represents an ongoing technological challenge. Solid-state emitters for instance typically exhibit inhomogenous frequency broadening due to charge noise. Current mitigation strategies such as feedback loops or post-selection introduce a large experimental overhead or drastically reduce the usable photon rate. In this work, we demonstrate a conceptually simple and efficient all-optical spectral control protocol on a nitrogen vacancy center in diamond. We observe that periodic excitation by optical π-pulses during the excited state lifetime reduces the emitter linewidth almost to the lifetime limit. Half of the spectral weight can be shifted to a target frequency selected by the pulse carrier frequency. The protocol [Fotso et al., PRL 116, 033603 (2016)] was proposed for the universal two-level system, rendering our approach applicable to a wide range of atomic and solid-state single-photon sources. Our work establishes a promising new avenue towards scalable sources of indistinguishable single photons.
Keywords: single photon source; two-level system; spectral diffusion; solid-state emitter; spectral engineering