RQC Seminar

77th RQC Seminar

• Speaker

  Prof. Mark Mitchison
  ( School of Physics,
  Trinity College Dublin, Ireland )

• Date

  16:00-17:00, August 21, 2023 (Monday)

• Venue

  Hybrid(ZOOM・ Wako Main Research 3F 345-347 Seminar Room

• Title

  Current fluctuations in continuously measured quantum systems: lessons from the critical Kerr model

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
Continuously measured quantum systems are characterized by an output current, in the form of a stochastic and correlated time series which conveys crucial information about the underlying quantum system. In this talk, I will present a theoretical framework to describe current fluctuations, which brings together concepts from continuous measurement theory and full counting statistics into a unified toolbox [1]. As an application, I will discuss current fluctuations in the parametrically pumped Kerr (PPK) model. The PPK model describes a driven-dissipative nonlinear cavity, whose nonequilibrium phase diagram features both continuous and discontinuous quantum phase transitions. When continuously measuring light leaking from the cavity, the photocurrent shows interesting divergences near criticality, whose nature depends both on the order of the phase transition and the choice of measurement basis [2]. These findings highlight the rich features of current fluctuations near nonequilibrium phase transitions in quantum-optical systems. Time permitting, I will also provide an outlook on some interesting future directions related to strongly coupled transport problems [3,4] and the thermodynamics of clocks [5,6].

[1] G. T. Landi, M. J. Kewming, M. T. Mitchison ＆ P. P. Potts, arXiv:2303.04270
[2] M. J. Kewming, M. T. Mitchison ＆ G. T. Landi, Phys. Rev. A 106, 033707 (2022)
[3] M. Brenes et al., Phys. Rev. X 10, 031040 (2020)
[4] A. M. Lacerda et al., Phys. Rev. B 107, 195117 (2023)
[5] P. Erker et al., Phys. Rev. X 7, 031022 (2017)
[6] O. Culhane et al., arXiv:2307.09122