RQC Seminar

259th RQC Seminar

• Speaker

  Dr. Anton Frisk Kockum
  ( Chalmers University of Technology, Sweden )

• Date

  16:00-17:00, (4:00 p.m.-5:00 p.m.) Thursday, April 2, 2026

• Venue

  Hybrid( Zoom,
  345-347 Seminar Room, 3F, Main Research Building, Wako Campus / 和光地区 研究本館3階 セミナー室 (345-347) (C01))

• Title

  Modelling, Wiring, and Characterizing Quantum Computers with Hundreds of Qubits

• Inquiries

  norilab_rqc_assist[at]ml.riken.jp

Abstract
As quantum computers now are scaling to sizes of hundreds of qubits and beyond, a multitude of both practical and theoretical challenges arise. On the theory side, the exponential growth of the Hilbert space with qubit number makes it difficult to accurately model and measure static properties and dynamic processes on the quantum computer. On the experimental side, for solid-state quantum processors operated at millikelvin temperatures, having individual control lines for each qubit go down into the cryostat runs into problems with increasing thermal load and lack of space as the qubit number grows. In this talk, I will present recent work in my theory group addressing these scaling challenges. First, I will show that reducing the number of control lines for a quantum computer by incorporating switches and time-multiplexed control leads to a surprisingly small overhead in the execution time for quantum algorithms, improving the outlook for scaling up quantum computers [1]. Then, I will demonstrate how we use numerical techniques adapted from many-body quantum physics to calculate properties such as ZZ coupling and localization across quantum processors with several hundred qubits [2]. Finally, I will also discuss selective quantum state tomography, which enables us to extract partial information of many-qubit states using relatively few measurements [3].

[1] Richter et al., arXiv:2508.20752, accepted in PRX Quantum (2026)
[2] Pettersson Fors et al., in preparation (2026)
[3] Patel et al., arXiv:2503.20979, accepted in Phys. Rev. Res. (2026)