Quantum computing just got hotter: 1 degree above absolute zero

By Andrew Dzurak, Andre Luiz Saraiva De Oliveira, UNSW Sydney

For decades, the pursuit of quantum computing has struggled with the need for extremely low temperatures, mere fractions of a degree above absolute zero (0 Kelvin or –273.15°C). That’s because the quantum phenomena that grant quantum computers their unique computational abilities can only be harnessed by isolating them from the warmth of the familiar classical world we inhabit.

A single quantum bit or “qubit”, the equivalent of the binary “zero or one” bit at the heart of classical computing, requires a large refrigeration apparatus to function. However, in many areas where we expect quantum computers to deliver breakthroughs – such as in designing new materials or medicines – we will need large numbers of qubits or even whole quantum computers working in parallel.

Quantum computers that can manage errors and self-correct, essential for reliable computations, are anticipated to be gargantuan in scale. Companies like Google, IBM and PsiQuantum are preparing for a future of entire warehouses filled with cooling systems and consuming vast amounts of power to run a single quantum computer.

But if quantum computers could function at even slightly higher temperatures, they could be much easier to operate – and much more widely available. In new research published in Nature, our team has shown a certain kind of qubit – the spins of individual electrons – can operate at temperatures around 1K, far hotter than earlier examples.

The cold, hard facts

Cooling systems become less efficient at lower temperatures. To make it worse, the systems we use today to control the qubits are intertwining messes of wires reminiscent of ENIAC and other huge computers of the 1940s. These systems increase heating and create physical bottlenecks to making qubits work together.

The more qubits we try to cram in, the more difficult the problem becomes. At a certain point the wiring problem becomes insurmountable.

After that, the control systems need to be built into the same chips as the qubits.

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