180th RQC Seminar

• 講演者

  Dr. Alberto Mercurio
  ( École Polytechnique Fédérale de Lausanne (EPFL), Switzerland )

• 日程

  2025年2月7日（金） 16:00-17:00 （4:00 p.m. -5:00 p.m.）

• 開催場所

  ハイブリッド（ZOOM・ Wako Main Research 3F 345-347 Seminar Room/ 研究本館3階 セミナー室(345-347) C01）

• 講演タイトル

  Renormalization and Low-Energy Effective Models in Cavity and Circuit QED

• お問合せ

  norilab_rqc_assist[at]ml.riken.jp

講演概要
The quantum Rabi model (QRM) is a cornerstone in the study of light-matter interactions within cavity quantum electrodynamics (QED). It effectively captures the dynamics of a two-level system coupled to a single-mode resonator, serving as a foundation for understanding phenomena in various fields, such as superconducting qubits, quantum dots, and trapped ions. However, at sufficiently large couplings, its predictions may deviate significantly from full models, and issues of gauge invariance in this truncated Hilbert space further undermine its reliability. In this work, we introduce a renormalized QRM, which incorporates the effective influence of higher atomic energy levels, providing a more accurate depiction of the system even under very strong coupling conditions. This model corrects the deviations observed in the standard QRM, thereby enhancing the precision of energy eigenvalues and physical observables. Additionally, we propose a gauge-invariant formulation, ensuring consistent and accurate results across different gauges. To demonstrate the versatility of this approach, we applied it to two different cases: a natural atom in a double-well potential, and the fluxonium qubit in circuit QED. This procedure is versatile and can be applied to any system in cavity and circuit QED, enhancing both experimental and theoretical investigations in the field of quantum information processing.