RQC Seminar

164th RQC Seminar

  • Speaker

    Mr. Gavin Barclay Crowder
    ( University of Ottawa, Canada )

  • Date

    16:00-17:00, November 1, 2024 (Friday)

  • Venue

    Hybrid(ZOOM・ Wako Main Research 4F 445-447 Seminar Room/研究本館3階 セミナー室(445-447) C01）

  • Title

    Quantum trajectory models and applications of time-delayed coherent feedback in waveguide-QED systems

  • Inquiries

    rqc_info[at]ml.riken.jp

Abstract
Feedback has been well used as a stabilization and control mechanism in photonics and other cutting-edge
technologies. However, typically the feedback is measurement-based, where the output is measured in order
to inform the control system. In this talk, I will discuss our recent work in modelling a time-delayed coherent
feedback using a quantum trajectory discretized waveguide model [1]. I will first show how this model can
accurately describe complicated dynamical regimes such as population trapping and enhanced spontaneous
emission states that arise from coherent feedback, and then present applications where the non-Markovian
aspect of the feedback is used to manipulate the multi-photon effects and nonlinear spectra from a qubit [2],
as well as improve single photon source performance [3]. I will then show how our model can connect to
recent waveguide-QED experiments with superconducting qubits.

[1] Sofia Arranz Regidor, Gavin Crowder, Howard Carmichael, and Stephen Hughes. Modeling quantum
light-matter interactions in waveguide QED with retardation, nonlinear interactions, and a time-delayed
feedback: Matrix product states versus a space-discretized waveguide model. Physical Review Research 3,
023030 (2021).
[2] Gavin Crowder, Lora Ramunno, and Stephen Hughes. Quantum trajectory theory and simulations of
nonlinear spectra and multiphoton effects in waveguide-QED systems with a time-delayed coherent feedback.
Physical Review A 106, 013714 (2022).
[3] Gavin Crowder, Lora Ramunno, and Stephen Hughes. Improving On-Demand Single Photon Source
Coherence and Indistinguishability Through a Time-Delayed Coherent Feedback, e-print: arXiv:2302.08093
(2023).



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