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QI: Fachverband Quanteninformation

QI 39: Quantum Foundations

QI 39.6: Vortrag

Freitag, 14. März 2025, 12:15–12:30, HS VIII

Witnesses for non-projectively simulable POVMs — •Raphael Brinster, Nikolai Wyderka, Hermann Kampermann, and Dagmar Bruß — Institut für Theoretische Physik III, Heinrich-Heine-Universität Düsseldorf

Quantum measurements are an indispensable tool in quantum information tasks like quantum computing and quantum cryptography. Usually, one distinguishes between projective measurements and generalised measurements (POVMs), where the latter perform better in certain tasks like unambiguous state discrimination. POVMs, that can be simulated by projective measurements acting on the same Hilbert space are called projectively simulable POVMs. In general, determining whether a given POVM is projectively simulable or not is a hard problem. Analogously to entanglement witnesses, we construct non-simulability witnesses from a hierarchy of semidefinite programs. These witnesses are linear maps, which can be evaluated using measurement statistics. A negative outcome certifies non-simulability. Using this tool we calculate upper bounds on the minimum amount of white noise one has to add to make every POVM in d dimensions simulable.

Keywords: POVM; Projective simulability; Semidefinite programming; Witnesses; Measurement