December 8, 2022

New superconducting thermometer for Quantum Computers

New superconducting thermometer for Quantum Computers The new quantum thermometer on a chip, in the foreground. It is probably the world’s fastest and most sensitive thermometer for measuring temperature at the cold end of a waveguide at the millikelvin scale, according to the Chalmers researchers. Credit: Claudia Castillo Moreno/Chalmers University of Technology

Researchers at Chalmers University of Technology, Sweden, have developed a novel type of thermometer that can simply and quickly measure temperatures during quantum calculations with extremely high accuracy. The breakthrough provides a benchmarking tool for quantum computing.

In order to have maximum control over microwave pulses driving the qubits, the researchers need to be sure that the related waveguides are not carrying noise due to thermal motion of electrons on top of the pulses that they send. In other words, they have to measure the temperature of the electromagnetic fields at the cold end of the microwave waveguides, the point where the controlling pulses are delivered to the computer’s qubits. Working at the lowest possible temperature minimizes the risk of introducing errors in the qubits.

An artistic impression of the superconducting circuit used in the experiment by Scigliuzzo et al. (left), and of its capability of measuring thermal microwaves at the level of a single excitation quantum (right). Credit: neuroncollective.com / Chalmers University of Technology
An artistic impression of the superconducting circuit used in the experiment by Scigliuzzo et al. (left), and of its capability of measuring thermal microwaves at the level of a single excitation quantum (right). Credit: neuroncollective.com / Chalmers University of Technology

Until now, researchers have only been able to measure this temperature indirectly, with relatively large delay. Now, with this innovation, very low temperatures can be measured directly at the receiving end of the waveguide – very accurately and with extremely high time resolution. (SciTech)

The paper has been published in Physical Review X.

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