Realizing a synthetic topological insulator with a quasi-periodically driven qubit

Speaker: Eric Boyers, Boston University, Physics Department

When: August 13, 2020 (Thu), 02:30PM to 03:30PM (add to my calendar)

This event is part of the Preliminary Oral Exam.

Synthetic dimensions are a class of techniques which extend the effective dimensionality of a system by introducing additional degrees of freedom that mimic spatial dimensions. These techniques have emerged as a major area of research in recent years as a means to enrich the physics accessible by experiments and study phenomena that cannot be easily realized in real space. Synthetic topological systems in particular have received much attention due to their close connection with topological pump systems and their potential applications in quantum simulation and devices. While synthetic topological systems have been demonstrated in a number of platforms, few attempts have been made to realize them in few-level systems. The long coherence times, robust read-out techniques, and precise controls of the Hamiltonians of solid state qubits make them promising candidates for creating synthetic topological systems. In this talk, I present an experimental demonstration of a model that realizes a synthetic topological insulator in a qubit using a quasi-periodically driven Nitrogen-vacancy center. By measuring the evolution of the overlap of states prepared at nearby points in the synthetic Brillioun zone, we perform a Loschmidt echo-like experiment that directly probes the Berry curvature and allows for the measurement of the Chern number. We find that the Chern number is integer quantized as expected and we use it to map out the phase diagram of the model. Our results show close agreement with theory, including an effective half-integer Chern number at a critical point in the model. This work establishes the feasibility of quasi-periodically driven qubits as a platform for synthetic dimensions and lays the groundwork for possible device applications such as frequency converters.

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