Higher-order mean-field theory of chiral waveguide QED

authored by
Kasper Kusmierek, Sahand Mahmoodian, Martin Cordier, Jakob Hinney, Arno Rauschenbeutel, Max Schemmer, Philipp Schneeweiss, Jürgen Volz, Klemens Hammerer

Waveguide QED with cold atoms provides a potent platform for the study of non-equilibrium, many-body, and open-system quantum dynamics. Even with weak coupling and strong photon loss, the collective enhancement of light-atom interactions leads to strong correlations of photons arising in transmission, as shown in recent experiments. Here we apply an improved mean-field theory based on higher-order cumulant expansions to describe the experimentally relevant, but theoretically elusive, regime of weak coupling and strong driving of large ensembles. We determine the transmitted power, squeezing spectra and the degree of second-order coherence, and systematically check the convergence of the results by comparing expansions that truncate cumulants of few-particle correlations at increasing order. This reveals the important role of many-body and long-range correlations between atoms in steady state. Our approach allows to quantify the trade-off between anti-bunching and output power in previously inaccessible parameter regimes. Calculated squeezing spectra show good agreement with measured data, as we present here.

Institute of Theoretical Physics
External Organisation(s)
Humboldt-Universität zu Berlin (HU Berlin)
Columbia University
University of Sydney
TU Wien (TUW)
SciPost Physics
No. of pages
Publication date
Publication status
Peer reviewed
ASJC Scopus subject areas
Condensed Matter Physics, Nuclear and High Energy Physics, Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics
Electronic version(s)
https://doi.org/10.48550/arXiv.2207.10439 (Access: Open)
https://doi.org/10.21468/SciPostPhysCore.6.2.041 (Access: Open)