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arXiv · 2407.12578

Crossing exceptional points in non-Hermitian quantum systems

Friederike U. J. Klauck·Matthias Heinrich·Alexander Szameit·Tom A. W. Wolterink
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Abstract

Exceptional points facilitate peculiar dynamics in non-Hermitian systems. Yet, in photonics, they have mainly been studied in the classical realm. In this work, we reveal the behavior of two-photon quantum states in non-Hermitian systems across the exceptional point. We probe the lossy directional coupler with an indistinguishable two-photon input state and observe distinct changes of the quantum correlations at the output as the system undergoes spontaneous breaking of parity-time symmetry. Moreover, we demonstrate a switching in the quantum interference of photons directly at the exceptional point, where Hong-Ou-Mandel dips are transformed into peaks by a change of basis. These results show that quantum interference and exceptional points are linked in curious ways that can now be further explored.

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Friederike U. J. Klauck, Matthias Heinrich, Alexander Szameit, Tom A. W. Wolterink. 2024-07-17. Crossing exceptional points in non-Hermitian quantum systems. https://doi.org/10.1126/sciadv.adr8275

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