289th RQC Seminar

• 講演者

  Dr. Sebastian de Graaf
  ( National Physical Laboratory )

• 日程

  2026年06月24日（水）, 15:30 - 16:30(3:30 p.m.-4:30 p.m.)

• 開催場所

  オンサイト（ Cooperation Center 5F W524, Wako Campus/ 和光地区 研究交流棟5階 W524 (S41)）

• 講演タイトル

  He-3 immersion cooling of superconducting quantum circuits

• お問合せ

  atsushi.noguchi[at]riken.jp

講演概要
The detailed microscopic mechanisms for decoherence in superconducting qubits remain an open question. Moreover, the measured properties of superconducting quantum circuits tend to plateau out far above the dilution refrigerator base temperature under usual experimental configurations, suggesting poor thermalisation of physical subsystems. Immersion cooling, in a quantum fluid bath of liquid He-3, provides a medium to effectively cool superconducting devices and potentially mitigate sources of decoherence. I will discuss recent experiments on superconducting resonators and qubits in the quantum immersion testbed at the London Low Temperature Laboratory, exploiting a cryogen-free adiabatic nuclear demagnetization refrigerator reaching temperatures below 1 mK. In particular, we find that He-3 can couple strongly to two-level system defects present in devices, providing new engineering possibilities to mitigate decoherence.