Freiburg 2024 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 38: Poster IV
Q 38.24: Poster
Mittwoch, 13. März 2024, 17:00–19:00, KG I Foyer
Active Polarization Modulation of Passive Entangled Photon Pair Sources — •Sabine Häussler1, Philippe Ancsin1, Meritxell Cabrejo-Ponce1,2, Rodrigo Gómez1,2, and Fabian Steinlechner1,2 — 1Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Straße 7, 07745 Jena, Germany — 2Friedrich Schiller University, Institute of Applied Photonics, Abbe Center of Photonics, Albert-Einstein-Str. 12, 07745 Jena, Germany
Entangled photon pair sources (EPS) are typically optimized to produce a single well-defined quantum state. While such passive sources are highly suitable for quantum key distribution (QKD), more advanced cryptographic protocols with multiple parties, such as quantum secret sharing (QSS), demand more flexible sources that incorporate active modulation. In our previous research, we have examined the feasibility for multi-partite QKD using an EPS with active state modulation. There, the EPS is based on a complete in-fiber Sagnac interferometer with a cascade of second-harmonic generation and downconversion in two nonlinear waveguides. This setup offers high brightness, phase stability, and high-speed active modulation. However, in this configuration, Raman noise in fibers represents an issue that limits performance. To overcome this restriction, the active modulation is moved outside the Sagnac loop to the pump preparation stage. This active system for polarization encoding is combined with a passive EPS, giving altogether a better performing system for flexible applications in QKD. The system was characterized regarding its applicability as a reconfigurable quantum network for QSS.
Keywords: State Modulation; Quantum Secret Sharing; Multi-User QKD; Polarization Entanglement