Photon-Based Heat Transport May Advance Quantum Computing

A thermal-transport method that uses photons as carriers has been demonstrated over 1-m distances. The fundamental advance in heat conduction could drive the development of quantum computers.

Artistic rendering of quantum-limited heat conduction of photons over macroscopic distances. Courtesy of Heikka Valja.

The successful operation of a quantum computer requires efficient cooling mechanisms. At the same time, a quantum computer is prone to errors caused by external noise. The photon-carrier method, developed in the lab of Mikko Möttönen at the University of Aalto, could be used to cool quantum processors without disturbing operation of the computer.

Möttönen and his team reported measurement of quantum-limited heat transport over distances up to a meter; previous measurements were only achieve distances of about 100 μm.

"For computer processors, a meter is an extremely long distance. Nobody wants to build a larger processor than that,” said Möttönen.

The transport method used a transmission line with no electrical resistance to transport microwave photons. The superconducting line was built on a 1-cm² silicon chip, and tiny resistors were placed at the ends of the line. Results were obtained by measuring induced changes in the temperatures of these resistors.

Based on their results, the researchers suggested that quantum-limited heat conduction has no fundamental distance cutoff. Their work established the integration of normal-metal components into the framework of circuit quantum electrodynamics, which provides a basis for the superconducting quantum computer.

The research was published in Nature Physics (doi: 10.1038/nphys3642).