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arXiv · 1906.07468

Topology with broken parity-time symmetry

Lei Xiao·Xingze Qiu·Kunkun Wang·Barry C. Sanders·Wei Yi·Peng Xue
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Abstract

Topological edge states arise in parity-time ($\mathcal{PT}$)-symmetric non-unitary quantum dynamics but have so far only been discussed in the $\mathcal{PT}$-symmetry-unbroken regime. Here we report the experimental detection of robust topological edge states in one-dimensional photonic quantum walks with spontaneously broken $\mathcal{PT}$ symmetry, thus establishing the existence of topological phenomena therein. We theoretically prove and experimentally confirm that the global Berry phase in non-unitary quantum-walk dynamics unambiguously defines topological invariants of the system in both the $\mathcal{PT}$-symmetry-unbroken and broken regimes. As topological edge states exist in both $\mathcal{PT}$ unbroken and broken regimes, we reveal that topological phenomena are not driven by $\mathcal{PT}$ symmetry.

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Lei Xiao, Xingze Qiu, Kunkun Wang, Barry C. Sanders, Wei Yi, Peng Xue. 2019-06-18. Topology with broken parity-time symmetry. https://arxiv.org/abs/1906.07468

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