Scientists have developed a new kind of cryogenic computer chip that can function at such cold temperatures that it approaches the theoretical limit of absolute zero.
This cryogenic system, called Gooseberry, lays the foundation for a revolution in quantum computing – enabling a new generation of machines to perform computations with thousands of qubits or more, while today’s most advanced devices exist only in tens.
“The world’s largest quantum computers currently operate at just 50 or so,” explains quantum physicist David Reilly of the University of Sydney and Microsoft’s Quantum Laboratory.
“This small scale is due in part to the limitation of the physical architecture that controls the qubits.”
The physical architecture is limited due to the extreme conditions that qubits need to perform quantum mechanical calculations.
The Gooseberry chip (red) next to a qubit test chip (blue) and resonator chip (purple). (Microsoft)
Unlike the binary bits on traditional computers, which occupy either a value of 0 or 1, qubits occupy a quantum superposition – an undefined and unmeasured state that can effectively represent both 0 and 1 at the same time in the context of a larger mathematical operation.
This esoteric principle of quantum mechanics means that quantum computers could theoretically solve very complex mathematical problems that classical computers would never be able to answer (or take years).
As with conventional technology, however, more is always better, and so far researchers have been limited in the amount of qubits they could successfully use in quantum systems.
One of the reasons for this is that qubits require extreme cold levels to function (in addition to other controlled conditions), and that the electrical wiring used in today’s quantum computer systems inevitably produces small but sufficient heat levels that disrupt the thermal requirements.
Scientists are investigating ways to circumvent this, but many quantum innovations have so far relied on the construction of bulky wiring equipment to keep the temperature stable for increasing the number of kwbit, but the solution has its own limits.
“Current machines create a beautiful series of wires to control the signals; it looks like an inverted gilded bird’s nest or chandelier,” says Reilly.
“They are beautiful, but fundamentally impractical. That means we can not scale up the machines to perform useful calculations. There is a real problem for import and export.”
The solution for the bottleneck could be gooseberry: a cryogenic control chip that can work at ‘millikelvin’ temperatures only a small fraction of a degree above absolute zero, as described in a new study.
That extreme thermal capacity means that it can sit with the qubits inside the supercooled cooling environment, connect with each other and transmit signals from the qubits to a secondary core that sits outside in another extremely cold tank, immersed in liquid helium.
In doing so, it removes all the excess wiring and the excess heat they generate, which means that today’s qubit bottlenecks in quantum computers may soon be a thing of the past.
“The chip is the most complex electronic system that can work at this temperature,” Reilly explained to Digital Trends.
“This is the first time that a mixed-signal chip with 100,000 transistors operates on 0.1 kelvin, [the equivalent to] –459.49 degrees Fahrenheit, or –273.05 degrees Celsius. “
Eventually, the team expects their system to be able to control thousands of qubits through the cryogenic chip – about a 20-fold increase in what is possible today. In the future, the same kind of approach could enable quantum computing on a whole different level.
“Why not start thinking about billions of quarters?” Reilly tells the Australian financial review. “The more qubits we can control, the better.”
Although it may take a while before we see that this cryogenic breakthrough is practically used outside the laboratory, there is no doubt that we are looking at a big step forward in quantum computing, experts say.
“It’s going to be transformation in the next few years,” Andrew White, director of the ARC Center of Excellence for Engineered Quantum Systems, who was not involved in the study but oversaw quantum research in Australia, told ABC News .
“If everyone [developing quantum computers] do not use this slide, but they will use something inspired by it. ‘
The findings are presented in Natural Electronics.