A team of researchers from the National Institute of Informatics (NII) in Tokyo and NTT Basic Research Laboratories (BRL, Nippon Telegraph and Telephone Corporation) in Japan have published an explanation of how quantum systems may be able to heat up by cooling down. Their paper appeared recently in Physical Review Letters.
“Heating by cooling sounds rather counterintuitive, but if the system has symmetries, decay could mean many things,” says Kae Nemoto, a professor in the Principles of Informatics Research Division at NII which is part of the Inter-University Research Institute Corporation Research Organization of Information and Systems (ROIS).
Nemoto and her team examined a double sub–domain system coupled to a single constant temperature reservoir. Each sub-domain contained multiple spins—a form of angular momentum carried by elementary particles such as electrons and nuclei. The researchers considered the situation in which the spins within each sub-domain are aligned with respect to each other, but the sub-domains themselves are oppositely aligned (for instance all up in one and all down in the second). This creates a certain symmetry in the system.