New groundbreaking cryogen-free micro-Kelvin refrigerator jointly developed by Oxford Instruments and Royal Holloway University of London
24 October 2013

Oxford Instruments and Royal Holloway University of London (RHUL) have jointly developed the first refrigerator capable of achieving micro-Kelvin temperatures without the use of liquid cryogens. This unique system breaks all previous Cryofree® temperature records and opens up a new market for research applications in quantum computing and condensed matter physics.

Engineers and scientists combined Oxford Instruments’ market leading TritonTM dilution refrigerator integrated with a superconducting magnet and a nuclear demagnetization stage developed by RHUL. They successfully maintained temperatures below 1 milli-Kelvin for more than 24 hours with a lowest temperature of 600 micro-Kelvin. To be able to measure such low temperatures reliably RHUL developed a current sensing noise thermometer.

The combination of several key technologies was instrumental to the success of this prototype system. The ultra-low vibration characteristics of the dilution refrigerator prevented excessive heating of the coldest stage and the selection of PrNi5 as the nuclear refrigerant, instead of more conventional high-purity copper, helped reducing the effect of eddy-current heating. The team also expects to improve their results further by optimizing the magnet system.

Dr Andrew Casey, lecturer at RHUL commented on the results: "This project has highlighted to me the benefits of industrial involvement when the research needs of the scientific community converge with the vision of the company".

Dr Michael Cuthbert, Technical Director at Oxford Instruments further stated: “Our collaboration with RHUL has been running for many years now across a variety of low temperature projects and this latest result is a particularly impressive milestone. Developing cryogen free technology for ultra low temperatures has opened up new markets and new applications. Extending this temperature range down below 1mK provides new cooling platforms to the research community to further investigate quantum mechanical regimes in extreme environments.”

Read more about the system at http://arxiv.org/abs/1307.7049.