From Floquet to Dicke: quantum spin-Hall insulator interacting with quantum light

Abstract

Time-periodic perturbations due to classical electromagnetic fields are useful to engineer the topological properties of matter using the Floquet theory. Here we investigate the effect of quantized electromagnetic fields by focusing on the quantized light-matter interaction on the edge state of a quantum spin-Hall insulator. A Dicke-type superradiant phase transition occurs at arbitrary weak coupling, the electronic spectrum acquires a finite gap and the resulting ground state manifold is topological with Chern number $\pm 1$. When the total number of excitations is conserved, a photocurrent is generated along the edge, being pseudo-quantized as $\omega \ln (1/\omega )$ in the low frequency limit, and decaying as $1/\omega$ for high frequencies with $\omega$ the photon frequency. The photon spectral function exhibits a clean Goldstone mode, a Higgs like collective mode at the optical gap and the polariton continuum.

5 pages, 3 figures, revised version

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• Realistic Time-Reversal Invariant Topological Insulators With Neutral Atoms
• Engineering Time-Reversal Invariant Topological Insulators With Ultra-Cold Atoms
• Dissipative Floquet Topological Systems
• Polariton condensation with localised excitons and propagating photons
• Topological Insulators and Metals in Atomic Optical Lattices
• Superradiant Solid in Cavity QED Coupled to a Lattice of Rydberg Gas

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• Disorder-Driven Density and Spin Self-Ordering of a Bose-Einstein Condensate in a Cavity
• Generating controllable type-II Weyl points via periodic driving
• Unified Light-Matter Floquet Theory and its Application to Quantum Communication
• Stability of a Bose-Einstein condensate in a driven optical lattice: Crossover between weak and tight transverse confinement
• Non-Fermi-Liquid Behavior from Cavity Electromagnetic Vacuum Fluctuations at the Superradiant Transition
• Disorder-induced topology in quench dynamics
• Superradiant phase transitions in one-dimensional correlated Fermi gases with cavity-induced umklapp scattering
• Quantum-vacuum-protected topological edge polaritons
• Photon-mediated electronic correlation effects in irradiated two-dimensional Dirac systems
• Collective modes for helical edge state interacting with quantum light