Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 12: Quantum Computing and Simulation II

Q 12.6: Talk

Monday, March 2, 2026, 18:30–18:45, P 10

Integrated generation of photonic graph states for measurement-based quantum computing — •Jeldrik Huster^{1, 2}, Louis Hohmann^{1, 2}, and Stefanie Barz^{1, 2} — ¹Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569 Stuttgart, Germany — ²Center for Integrated Quantum Science and Technology (IQST)

Photonic quantum devices have been used to demonstrate a broad range of quantum applications, namely quantum computation, communication and network applications. Essential for the scaling to higher qubit numbers, are integrated solutions in the telecom band, due to their small footprint, high phase stability and low loss connectivity. Most photonic implementations rely on multipartite entangled states, especially graph states. Here, we present our recent progress on a silicon on insulator photonic chip for the generation of graph states with up to four qubits. We generate four-qubit Greenberger-Horne-Zeilinger (GHZ) and linear graph states with fidelities of over 83% and 75%, respectively. These states are used to show photonic measurement-based quantum computing (MBQC). We demonstrate single-qubit and two-qubit gates as well as the implementation of Grover’s search and Deutsch’s algorithm. This is made possible by the chip’s high coupling efficiency to single modes fibres and reconfigurability via tuneable beam splitter and phase shifters.

Keywords: Integrated photonics; Silicon-on-insulator; SPDC; MBQC; Graph states