Quantum Refrigeration

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University of Bristol, School of Physics - News and features
News and features archive - December 2009 to September 2010

The smallest possible refrigerator

3 September 2010
Experts in quantum mechanics at the University of Bristol have designed what is arguably the smallest possible refrigerator. They dealt not just with questions of engineering, or how small one can build a refrigerator, but also with fundamental limitations that nature may impose on the size of refrigerators. Is there a minimum size below which no refrigerator can work?
The Bristol team – Professor Noah Linden, Professor Sandu Popescu and Paul Skrzypczyk – found there is no minimum size, and, using quantum mechanics, designed what is arguably the smallest possible refrigerator. It works extremely well too: it can cool as close as you like towards absolute zero. One model refrigerator is made from just three two-level quantum systems – the simplest possible physical systems, known as qubits. Two of the qubits make up the refrigerator – one in a hot heat bath, the other in a heat bath at "room temperature" - the third is the object to be cooled. In addition to their interaction with their local heat baths, the qubits interact with each other. As the hot qubit absorbs energy from its bath, it causes the tepid qubit to siphon energy from the third qubit, thus cooling it.
Nicolas Gisin, a theoretical and experimental physicist at the University of Geneva, who was not involved with the work, remarks that this result is "extremely elegant. It opens a totally new avenue for interesting questions, combining thermodynamics and quantum information science in a very original way."
To find out more, see University of Bristol news page, and Science - Quantum Physicists Dream Up Smallest Possible Refrigerator.

Retrieved by DonEMitchell 09:01, 8 August 2012 (MDT) from http://www.phy.bris.ac.uk/news_archive1.html