RQC Seminar

120th RQC Seminar

• Speaker

  Dr. Alexander Tzalenchuk
  ( National Physical Laboratory, Teddington UK
  Royal Holloway, University of London, Egham UK )

• Date

  13:00-14:00, June 10, 2024 (Monday)

• Venue

  Hybrid(ZOOM・ Wako C61 Welfare ＆ Conf. 2F Large Meeting Room）

• Title

  Towards quantum materials science for superconducting circuits

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
Simultaneous advance in the scale and quality of quantum computers is required to achieve fault-tolerance. Superconducting circuits comprising qubits and resonators have emerged as a viable platform for quantum computers. A major issue facing the implementation of complex superconducting quantum circuits is their interaction with incidental two-level systems (TLS). These notoriously ubiquitous defects resulting from atomic-scale materials imperfections are the source of noise, decoherence, and parameter fluctuations. Improvements upon the device design have yielded most of the gain in coherence times over the last decades. This resource looks all but exhausted by now. Eliminating TLS on the other hand requires major advances in materials analysis performed at the qubit operation temperatures in the millikelvin range and relevant energies corresponding to some gigahertz.
To this end we use planar superconducting resonators as a probe for the TLS physics. In this talk I will overview recent progress in identification of a variety of these detrimental defects using in-situ and in-operation spectroscopic techniques. I will also present recent work on immersion cooling of superconducting resonators in 3He which results in improved TLS thermalisation and presents a route towards less noise and improved parameter stability. This development suggests that quantum engineering may benefit from access to a wider arsenal of quantum condensed matter.