TY - JOUR

T1 - Higher-order mean-field theory of chiral waveguide QED

AU - Kusmierek, Kasper

AU - Mahmoodian, Sahand

AU - Cordier, Martin

AU - Hinney, Jakob

AU - Rauschenbeutel, Arno

AU - Schemmer, Max

AU - Schneeweiss, Philipp

AU - Volz, Jürgen

AU - Hammerer, Klemens

N1 - Funding Information: This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under SFB 1227 ‘DQ-mat’ project A06 - 274200144 and Germany’s Excellence Strategy -EXC-2123 QuantumFrontiers - 390837967, the Alexander von Humboldt Foundation in the framework of the Alexander von Humboldt Professorship endowed by the Federal Ministry of Education and Research, as well as the European Commission under the project DAALI (No.899275). M. C. and M. S. acknowledge support by the European Commission (Marie Skłodowska-Curie IF Grant No. 101029304 and IF Grant No. 896957).

PY - 2023/6/7

Y1 - 2023/6/7

N2 - 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.

AB - 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.

KW - quant-ph

KW - physics.atom-ph

UR - http://www.scopus.com/inward/record.url?scp=85162256041&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2207.10439

DO - 10.48550/arXiv.2207.10439

M3 - Article

VL - 6

JO - SciPost Physics

JF - SciPost Physics

IS - 2

M1 - 041

ER -