Detecting topological invariants in nonunitary discrete-time quantum walks

Abstract

We report the experimental detection of bulk topological invariants in nonunitary discrete-time quantum walks with single photons. The nonunitarity of the quantum dynamics is enforced by periodically performing partial measurements on the polarization of the walker photon, which effectively introduces loss to the dynamics. The topological invariant of the nonunitary quantum walk is manifested in the quantized average displacement of the walker, which is probed by monitoring the photon loss. We confirm the topological properties of the system by observing localized edge states at the boundary of regions with different topological invariants. We further demonstrate the robustness of both the topological properties and the measurement scheme of the topological invariants against disorder.

6 pages, 4 figures

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Cited by in corpus (5)

• New topological invariants in non-Hermitian systems
• Non-Bloch topological invariants in a non-Hermitian domain-wall system
• Topological phase and lattice structures in spin chain models
• Observation of novel robust edge states without bulk-boundary correspondence in non-Hermitian quantum walks
• Topology with broken parity-time symmetry