The research stems from the work of physicist Brian JosephsonSQUIDs), which are now sold commercially as ultra-sensitive magnetometers. In the latest work, researchers measured the devices’ thermal behaviour. The duo heated one end of a SQUID several micrometres long and monitored the temperature of an electrode connected to it. A SQUID consists of two y-shaped pieces of superconductor joined together to form a loop, but with two thin pieces of insulating material sandwiched in between. As the researchers varied the magnetic field passing through the loop, they found that the amount of heat flowing through the device also changed. The device worked by partly reversing the heat transfer, so that some would flow from the colder body to the warmer one."
Link to Original Source