Departmental Seminar

NLPC Department Seminar - Topological and Localised States in Waveguide QED

Ms Janet Zhong
Australian National University

Waveguide quantum electrodynamics (QED) is a subfield of quantum optics that studies arrays of atoms coupled to a waveguide. Confining the propagation of light to a one-dimensional (1D) channel enhances the atom-photon interaction strength which is crucial for many quantum information applications.

It also allows for infinite-range atom-atom interactions mediated by photons that give rise to a plethora of exotic effects such as the fermionisation of photons, interaction-induced localisation, bound photons and even quantum chaos. In the first part of this talk, I focus on a specific kind of localisation in the two-photon subspace of waveguide QED which are self-induced topological edge states. The hallmarks of the quantum Hall effect can be found in our model, from Landau levels to a Hofstadter-like butterfly energy spectrum.

In the second part of this talk, I provide
the first classification of eigenstates in the three-photon subspace of waveguide QED and show that the rich interplay of effects from order, chaos to localisation found in two-photon systems extends naturally to three-photon systems. There also exist interaction-induced localised states unique to three-photon systems such as bound trimers, corner states and trimer edge states. 

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