Mainz 2026 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 20: QuanTour II – Multi-photon Effects & Entanglement
Q 20.7: Vortrag
Dienstag, 3. März 2026, 12:45–13:00, P 7
High-fidelity entangled photon pairs from a quantum-dot-based single-photon source — •Malwina A. Marczak1, Timon L. Baltisberger1, Mark R. Hogg1, Spencer Johnson2, Nathan Arnold2, Benjamin Nussbaum2, Sascha R. Valentin3, Arne Ludwig3, Paul Kwiat2, and Richard J. Warburton1 — 1University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — 2University of Illinois, 337 Loomis Laboratory, 1110 W. Green Street, Urbana IL 61801, USA — 3Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
Entangled photon pairs are a ubiquitous resource in quantum technologies, used in quantum key distribution and quantum networking. For scalable quantum networks, pairs that are indistinguishable in all degrees of freedom are essential, as they enable high-fidelity entanglement swapping across network nodes. We demonstrate a high-fidelity source of "swappable" entangled photon pairs using a semiconductor quantum dot (QD) coupled to a tunable microcavity. By actively modulating the QD emission between orthogonal polarization states, delaying one path in a low-loss Herriott cell, and recombining the two on a balanced beam splitter, we generate entangled photon pairs with a fidelity of 96%. The photons are mutually indistinguishable, enabling efficient entanglement swapping, a crucial requirement for quantum repeaters. We identify and mitigate fidelity-limiting factors, achieving a maximum fidelity of 98.9% through time-resolved post-selection that suppresses residual multi-photon events concentrated near the excitation pulse.
Keywords: Quantum dots; Single photon sources; Entangled photon pairs; Quantum networks