A scalable mixed-refrigerant Joule-Thompson (MRJT) cryogenic system for trapped-ion quantum computers

There has been a great deal of effort and progress made towards building a fully scalable quantum computer but there are still significant engineering challenges to overcome.

Trapped ions currently represent a promising technology towards achieving this goal but a key engineering challenge is thermal management of ion-trap chips with increasing size. Currently commercial GM-type cryocooler can cool down to 4-70 K but vibration is another challenge.

Joule-Thompson (J-T) cryocooler is promising in this temperature range but there are no substances in nature that has boiling point between nitrogen (70K) and neon (27K).

In this project, we propose a mixed-refrigerant J-T (MRJT) cryogenic system that is scalable, efficient, and vibration-free, offering disruptive solution for cooling ion-trap chips.

Thermophysical properties will be modelled and validated for combined cryogens and possibly hydrocarbons for 30-70 K whilst single stage opposed-piston oil-free linear compressor will be developed to deliver the mixed-refrigerant flow with pressure ratio adjusted by vortex tube. A system model will be built to predict the cooling performance and optimise the geometries.

The model will be validated using test rigs at TFMRC, industrial partners and academic collaborators.

The successful development of MRJT will pave the way for trapped-ion quantum computers whilst the knowledge of general J-T cryocooler will be beneficial to all kinds of quantum technologies.