Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 23: Poster I

Q 23.27: Poster

Tuesday, March 12, 2024, 17:00–19:00, Tent B

Wave-particle duality in weighted two-way interferometers: Which-way knowledge increase via delayed observable choice — •Elisabeth Meusert, Marc-Oliver Pleinert, and Joachim von Zanthier — Quantum Optics and Quantum Information Group, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 1, 91058 Erlangen, Germany

The concept of wave-particle duality lies at the heart of quantum mechanics and appears, for example, in Young's well-known double slit experiment. There, the simultaneous observations of a visible interference pattern and the acquisition of which-way knowledge about the photon's path are limited by an inequality, dubbed the duality relation. Previous studies on symmetric interferometers showed that the obtained which-way knowledge can be correlated to the quantum object's phase for certain observables, and used this phase-dependency to increase the which-way knowledge above the duality relation-limit via delayed observable choice.

Our studies generalize these findings to arbitrarily weighted interferometers. We find again that the now weight- and phase-dependent which-way knowledge can be increased beyond the duality-relation limit. Moreover, we find that specific observables provide the highest improvement in which-way knowledge at asymmetric interferometer weights. These findings suggest that both the maximum achievable which-way knowledge and the highest possible knowledge increase might be available in unbalanced interferometers, at a value not obtainable from symmetry arguments.

Keywords: Wave-particle duality; Which-way knowledge; Interferometers