Technology

Heat Transfer Breakthrough Brings Quantum Computer Closer To Reality

February 2, 2016 | by Alfredo Carpineti

Photo credit: Artistic impression of quantum-limited heat conduction of photons over macroscopic distances. Heikka Valja

Every device heats up while in use, and while it is usually just an annoyance, it’s a big deal in quantum computing. Heat can actually affect the results of computation, so physicists have been looking for ways to efficiently cool down quantum circuits.

Now, a team from the Aalto University, led by Professor Mikko Möttönen, has been able to transport heat with maximal efficiency to a distance of one meter (40 inches). One meter might not seem like much, but the previous attempts were to distances shorter than the thickness a human hair. The invention could be used to cool down quantum computers in a way that the operations being conducted are not disturbed.

Their technology uses a heat transfer channel, in this case a superconducting thin wire made of aluminium. In the experiment, microwave photons moved along the wire, carrying heat from one side of the circuit to the other. Showing this is possible means that, in principle, photons could be used in a similar manner to transfer heat a large distance from a quantum computer without affecting its performance. 

Speaking to IFLScience, Möttönen said: “We’ve seen this quantum-limited heat conduction 10,000 times further than ever before.

“Quantum-limited means that there is an upper limit of how much heat can be transferred by a single [wire]. If you have multiple [wires] you can obviously transfer more heat.“

The research, which was published this week in Nature Physics, improves on previous approaches that used, for example, electrons as the heat carrier. Photons are great at transporting heat over long distances, and by using this method they were able to extend quantum-limited heat transfer from about 100 microns to one meter. The new technology used the phenomenal properties of superconductors to achieve the feat.

“We use aluminum to make these micron and nano-scale circuits, and when we cool them down to absolute zero, they turn superconductive and they start behaving quantum mechanically,” added Möttönen.

“In the future, we are looking into using this technology that we have now developed for this experiment and integrate it with the quantum bits. We want to show it can be useful for quantum computers.”

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