Radiative topological biphoton states in modulated qubit arrays

Date

2020

Authors

Ke, Yongguan
Zhong, Janet
Poshakinskiy, A. V.
Kivshar, Yuri
Poddubnyy, Alexander
Lee, Chaohong

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Volume Title

Publisher

American Physical Society

Abstract

We study topological properties of bound pairs of photons in spatially modulated qubit arrays (arrays of two-level atoms) coupled to a waveguide. While bound pairs behave like Bloch waves, they are topologically nontrivial in the parameter space formed by the center-of-mass momentum and the modulation phase, where the latter plays the role of a synthetic dimension. In a superlattice where each unit cell contains three two-level atoms (qubits), we calculate the Chern numbers for the bound-state photon bands, which are found to be (1,-2, 1). For open boundary conditions, we find exotic topological bound-pair edge states with radiative losses. Unlike the conventional case of the bulk-edge correspondence, these novel edge modes not only exist in gaps separating the bound-pair bands but they also may merge with and penetrate into the bands. By joining two structures with different spatial modulations, we find long-lived interface states which may have applications in storage and quantum information processing.

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Source

Physical Review Research

Type

Journal article

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Access Statement

Open Access

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