QMT Seminar: RF on-wafer measurements at cryogenic temperatures

QMT Seminar

Date: 11th June 2025

Time: 15:00-16:00

Location: Tolansky T125

To introduce the system and its capabilities, we will host a seminar by Dr Xiaobang Zhang (NPL), with an opening presentation by Dr Tobias Lindström (NPL) on NPL–RHUL collaborations. Dr Zhang will discuss the design and optimisation of the system that is now operational.

There will also be an in-person showcase of the device with limited avaliability.

Abstract:
Cryogenic on-wafer measurement of RF planar circuits - used in qubit control and readout - plays a crucial role in the development of scalable quantum computers. This approach allows direct characterisation of the device under test at cryogenic temperatures, eliminating the need for coaxial connectors or switches.

This talk will present recent developments in cryogenic on-wafer S-parameter measurements at NPL, carried out in close collaboration with Royal Holloway, University of London. Topics to be covered include the adaptation and optimisation of a cryogenic probe station for RF measurement at around 4 kelvin, the development of bespoke calibration and verification standards based on coplanar waveguide (CPW) structures, and ongoing efforts to extend the measurement capability to include noise figure characterisation. An overview of the state-of-the-art in this field will also be provided by reviewing similar work conducted by other research groups globally. Such cryogenic on-wafer measurement capabilities will help facilitate current and future developments in commercial quantum computers.