Gullans, Michael

Date: Thursday, June 23, 2016
Time: 11:00
Place: ETH Zurich, Hönggerberg, HPF G 6
Host: Atac Imamoglu

Effective Field Theory for Strongly Interacting Photons

Michael Gullans
NIST, Gaithersburg, USA

A promising route to scaling up quantum information systems is to strongly couple light, or other propagating quantum fields, to localized electronic degrees of freedom in solids or trapped atoms. These systems can be studied theoretically in analogous fashion to semiclassical nonlinear optics, where the electronic degrees of freedom are integrated out to give rise to effective photon-photon interactions.  In this talk, I will describe an approach we recently developed, based on effective field theory (EFT), to describe interacting photons in cold gases of Rydberg atoms.  In these systems, the photons become dressed with highly excited Rydberg states to form so-called "Rydberg polaritons". Using EFT, I will describe non-perturbative effects in N-body scattering of Rydberg polaritons, including the formation of N-body bound states and N-body interactions between photons.  This work suggests that strongly interacting photons can realize new universality classes for few-body quantum systems.  

I will then describe the optical response of quantum Hall states in Dirac materials when the carrier mean-free path exceeds the resonant wavelength for the inter-band Landau level transitions.  In this regime, we find that the scattered light from the bulk can be used to image the disorder landscape, while the edge states can be used to generate coherent light with high orbital angular momentum.