Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 42: Quantum Effects
Q 42.1: Vortrag
Donnerstag, 9. März 2017, 11:00–11:15, P 4
Probing the measurement process in DTQW via recurrence — •Thomas Nitsche1, Regina Kruse1, Linda Sansoni1, Martin Štefaňák2, Tamás Kiss3, Igor Jex2, Sonja Barkhofen1, and Christine Silberhorn1 — 1Applied Physics, University of Paderborn, Germany — 2Department of Physics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Czech Republic — 3Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary
The measurement process plays a crucial role in quantum mechanics as it interrupts the unitary evolution of a state. The consequences are apparent when investigating the return probability (Polya-number) of a particle in a Hadamard walk on the line [1, 2]: Depending on whether the evolution is restarted or continued after the measurement, either a transient or a recurrent evolution can be observed. We investigate both cases experimentally for the first time by introducing sinks in a time-multiplexed quantum walk setup using a fast-switching electro-optic modulator (EOM). Monitoring the evolution of the walker over 39 steps reveals the fundamental differences of the two cases as predicted by theory: In the restart-regime, the Polya-number will gradually approach unity. In contrast, the continue-regime yields an asymptotic value of the Polya-number of 2/π, which is reached in good approximation after only four steps and then remains almost constant.
M. Štefaňák, I. Jex, and T. Kiss, PhysRevLett 100, 020501 (2008)
[2] F. A. Grünbaum, L. Velázquez, A. H. Werner, and R. F. Werner, Commun. Math. Phys. 320, 543 (2013)