Abstract
Non-Hermitian descriptions of quantum matter have seen impressive progress recently, with major advances in understanding central aspects such as their topological properties or the physics of exceptional points, the non-Hermitian counterpart of critical points. Here, we use single-photon interferometry to reconstruct the non-Hermitian Kibble-Zurek mechanism and its distinct scaling behavior for exceptional points, by simulating the defect production upon performing slow parameter ramps. Importantly, we are able to realise also higher-order exceptional points, providing experimental access to their theoretically predicted characteristic Kibble-Zurek scaling behaviour. Our work represents a crucial step in increasing the experimental complexity of non-Hermitian quantum time-evolution. It thus also furthers the quest to move the frontier from purely single-particle physics towards increasingly complex settings in the many-body realm.
Highlights
The foundational axioms of quantum mechanics impose a Hermitian structure on Hamiltonians
Our work represents a step toward increasing the experimental complexity of non-Hermitian quantum time evolution, as part of the quest to move the frontier from single-particle physics toward increasingly complex settings
This happens rather generically for systems in touch with an environment; experimental instances occurring in photonics [1,4], cold atoms [5,9], mechanical systems [10,12], and electric circuits [13, 17] have revealed rich single-particle properties induced by non-Hermiticity
Summary
The foundational axioms of quantum mechanics impose a Hermitian structure on Hamiltonians. The nonunitary many-body dynamics is broken down into the time evolution of different quasiparticle modes, which are encoded in the polarizations of photons, detectable through single-photon interference Such a framework enables the engineering of highly tunable non-Hermitian band structures and allows us to realize different classes of EPs with varying complexity. Such a framework enables us to systematically characterize the novel nonunitary dynamics pertaining to different types of EPs, which is visible in the dynamics of defect generation upon passage through the exceptional and/or critical point in the time domain, as captured by the venerable Kibble-Zurek mechanism This theory was originally proposed for domain formation in the early universe [31], applied to superfluid helium [32], [33], and extended to dissipative systems [34]. We set the velocity of p modes and to unity and the density of states to 1/π
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