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Q: Fachverband Quantenoptik und Photonik
Q 30: QuanTour III – Spin Physics & Coherence
Q 30.2: Vortrag
Mittwoch, 4. März 2026, 15:00–15:15, P 1
Spin-photon entanglement for the generation of multipho- tonic graph states — •Lara Couronné1,2, Hêlio Huet2, Emilio Annoni1,2, Petr Steindl2, Aristide Lemaître2, Martina Morassi2, Anton Pishchagin1, Sébastien Boissier1, Olivier Krebs2, Samuel Mister1, Stephen Wein1, Viviana Villafane1, Dario Fioretto1,2, and Pascale Senellart2 — 1Quandela, Massy, France — 2C2N, Palaiseau, France
Measurement-based quantum computing requires large multi-photon entangled states. We generate these resource states using InGaAs quantum dots as high-efficiency single-photon sources. Each dot holds an extra charge carrier whose spin state maps to the polarization of an emitted photon via optical selection rules, enabling the Lindner-Rudolph protocol.
A small transverse magnetic field causes spin precession. Triggering photon emission while the spin is in superposition produces spin-photon entanglement; repeating this cycle yields multi-photon cluster states. This approach has been shown by several groups and recently extended to more complex states.
In this talk, we present our implementation, achieving entanglement of up to 10 photons. The main challenges are limited spin coherence and excited-state precession. To mitigate these, we use dynamical decoupling to extend coherence and time-filtering to remove photons affected by long excited-state precession. These advances mark a key step toward small-scale demonstrations of fault-tolerant photonic quantum computing.
Keywords: spin-photon entanglement; multiphotonic graph state; measurement based quantum computing; quantum dot; dynamical decoupling