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Higher-order mean-field theory of chiral waveguide QED
by Kasper Kusmierek, Sahand Mahmoodian, Martin Cordier, Jakob Hinney, Arno Rauschenbeutel, Max Schemmer, Philipp Schneeweiss, Jürgen Volz, Klemens Hammerer
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Submission summary
| Authors (as registered SciPost users): | Kasper Jan Kusmierek · Maximilian Schemmer |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2207.10439v1 (pdf) |
| Date submitted: | 2022-07-22 14:48 |
| Submitted by: | Kusmierek, Kasper Jan |
| Submitted to: | SciPost Physics Core |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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Abstract
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.
Current status:
Reports on this Submission
Report #1 by Anonymous (Referee 1) on 2022-9-21 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2207.10439v1, delivered 2022-09-21, doi: 10.21468/SciPost.Report.5732
Strengths
1 - timely topic at the forefront of a currently very active and rapidely developing field
2- addresses an important computational problem in quantum many body physics applying a well established method in a novel context allowing to reach a so far unexplored parameter regime
3-direct connection of the theoretical model with a concrete experimental setup demonstrating convincing agreement between measurements and theory predictions
4-nice and well structured introduction to the cumulant expansion method used
5- novel results and insight obtained by using and comparing various oders of the expansion model
6-experimental confirmation provides good evidence for the power and potential of the approach; this supports the use of the method in other less experimentally accessible cases
Weaknesses
1-technical quality of the figures and in particular the graphical presentation of the theoretical results is rather low
- poor choice of thin and many similar and hard to discern linetypes
-too many lines per plot
-too many and too tiny axis annotations
-too many plots/figure resulting in long and hard to read captions
2-description of the basic features of the experimental implementation of the system is rather condensed and compact; while this might be already available in other publications, a short review in the Appendix would be helpful to non-experts
3-the motivation for certain model assumptions could be improved by some extra comments and qualitative arguments for non experts:
-why are the invidual positions of the atoms appearing nowhere in the model ?
- why totally neglect backscattering / backward emission of photons; can the results be expected to be particuarly sensitive to this ?
- why are collective effects of the outside fiber loss/decay here completely negligible as atomic distances are of wavelength size (see for comparison NJP, 21(2), 025004, 2019) ?
-why are terms <sigma^x sigma^z> generally ignored in the expansion ?
- in Fig.6: what does a "mean-field" result for g2(0) represent ?
4-intro part to previous theoretical modeling misses a couple of papers
Report
Upon some improvements in presentation this work is very well suited for the journal
Requested changes
1 - improve/split figures
2-some more detailed review of experimental apparatus in Appendix
3-comment and clarify on some model assumptions for a broader readership
4-possible references to add in the intro:
Physical Review A 89.4 (2014): 043831
Physical Review A 96.3 (2017): 033857.