The method will save millions of Dollors in cooling systems for these machines. Quantum chips may be alongside electronic chips, simplifying design
Now that the entire world faces a formidable scientific problem, such as finding new cures and vaccines against the coronavirus pandemic, the promise of quantum computing is perhaps more necessary than ever. Two reports published this Wednesday by the journal Nature have taken a giant step for this class of computers to go from the theoretical and experimental plane in which they are now to be able to face all kinds of practical problems in a few years.
The two investigations have reached the same result independently, one from Australia and the other from the Netherlands. Until now, it was only possible to perform quantum operations at temperatures close to absolute zero, that is, at 273 degrees below zero, or 0 degrees Kelvin. The new studies show how qubits, or quantum bits, can be computed at temperatures up to 15 times higher than those achieved so far.
In reality, it is only a degree and a half Kelvin more -from 0.1ºK to 1.5ºK, in the case of the Dutch group-, but moving away from absolute zero, or total absence of energy, is a gigantic leap from both the technological and economic point of view.
First, it means that quantum chips will be able to work alongside the electronic systems that control them, so the basic components of a quantum computer will no longer have to be separated, each at its own temperature, and joined by the thousands or millions of cables that would make its construction unfeasible. On the other hand, this apparently small increase in thermal energy equates to a saving of millions of euros in cooling systems.
“It’s still very cold,” admits Andrew Dzurak, a professor at the University of New South Wales in Sydney and the lead author of the Australian paper. “But it is a temperature that can be achieved by spending only a few thousand dollars, instead of the millions of dollars needed to cool the chips to 0.1 K,” he advances.
For quantum computing to be practical, qubits should work alongside traditional electronic components, rather than remain in isolation. The Dutch research center QuTech has managed to control quantum operators on a silicon chip, developed in collaboration with Intel. The objective of both groups is to achieve a circuit in which the qubits and the non-quantum elements of the system operate simultaneously.
“Increasing the temperature may seem like a small step, but it is a big leap when it comes to the cooling systems available,” says Luca Petit, PhD student and first author of the QuTech study. “In addition, at these temperatures the qubits no longer need to function in a vacuum, but can be immersed in a liquid, which makes everything much more practical,” he adds.
The temperature reached by the Dutch group -1.1ºK- is 50 times higher than that previously achieved in silicon chips, which, according to experts, will facilitate the integration of quantum computing with the most traditional electronic elements it needs to function. According to Menno Veldhorst, principal investigator of the Dutch group, the aim is to create an “integrated quantum chip“, capable of incorporating “quantum hardware and classical hardware” in a single piece. That will be the next eureka moment.