Highest temperature for an operational quantum computer chip

The highest temperature that a quantum computer chip has successfully operated at is about 271.65 °C (1.5 K, -456.97 °F) and was achieved by researchers led by Henry Yang at the School of Electrical Engineering and Telecommunications, University of New South Wales, as well as collaborators in Canada, Japan and Finland, as published in Nature on 15 April 2020.

Regular computers consist of ‘bits’ that can be either ‘off’ or ‘on’. In contrast, quantum computer’s use quantum bits known as ‘qubits’ which, like a regular computer, can be in the states ‘off’ or ‘on’ but also utilise the quantum phenomena of superposition to be in a combined state of ‘off and on’ at the same time. This ability to be in an uncertain state of both ‘off’ or ‘on’ at once means that quantum computers are much better able to deal with uncertain problems than regular supercomputers. Unlike a regular computer, which must run through every possible solution separately, a quantum computer can run through them all at once.

Quantum computers can only be run at incredibly cold temperatures because they need to be free from any changes in the qubit states caused by uncontrolled influences. High temperatures mean high energies, which can cause the qubit to switch between states. This experiment demonstrated two qubits successfully operating at around 1.5 °C above the coldest temperature possible in the universe.