Prof. Xue Peng and his team from Department of Physics of Southeast University detected topological invariants in nonunitary discrete-time quantum walks for the first time, and provided new basis for quantum simulation and computation. The latest research results was published in “Physical Review Letters”.
The research reports 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. The research confirms the topological properties of the system by observing localized edge states at the boundary of regions with different topological invariants. And it further demonstrates the robustness of both the topological properties and the measurement scheme of the topological invariants against disorder.
The theoretical collaborator of the article is Prof. Yi Wei of University of Science and Technology of China, and Prof. Barry C. Sanders of University of Calgary. The first author is a doctoral candidate instructed by Prof. Xue Peng. The research was supported by The Natural Science Foundation of China an Jiangsu Science Fund for Distinguished Young Scholars.