Nonlocal games: Self-testing, parallel repetition and device-independent randomness

PhD defence by Sigurd Anker Laursen Storgaard

Assessment Committee

Associate Professor Daniel Stilck França, Department of Mathematical Sciences, University of Copenhagen (Chairperson)
Professor Lyudmila Turowska, Chalmers University of Technology and University of Gothenburg
Junior Professor Chair Marc-Olivier Renou, INRIA Paris-Saclay

Supervisors

Associate Professor Laura Mancinska

Department

Department of Mathematical Sciences

Place

Building: Department of Computer Science, Room: Store UP-1, Universitetsparken 1, 2100 Copenhagen Ø

Email address to gain access to the thesis: sals@math.ku.dk.
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Short description of the thesis

Quantum technologies promise advantages that have no classical counterpart, but how can we verify these advantages without trusting the devices themselves? This thesis studies this question through “nonlocal games”: simple cooperative tasks in which separated players cannot communicate but may share quantum entanglement. It develops new mathematical and computational tools for certifying quantum states and measurements, and shows how to generate the maximum possible amount of private randomness from quantum systems of any dimension. It also reveals unexpectedly fragile behavior: a quantum advantage can disappear when a game is repeated, and even reappear after further repetitions. These results deepen our understanding of reliable quantum information processing.