A team of scientists and engineers from the University of Sydney, Microsoft and EQUS, the Australian Research Council Center of Excellence for Engineered Quantum Systems, has taken a step towards developing a new generation of powerful quantum computers.
The team, which published their findings in the Jan. 25 issue of Nature Electronics, invented a cryogenic computer chip that can operate at temperatures near absolute zero, which could enable a new generation of high-performance quantum computers capable of calculating thousands of qubits can perform , or more.
Qubits are the quantum equivalent of the bits used by traditional computers. Because qubits aren’t binary – they don’t process information using 0s and 1s – they are able to work much faster. For various reasons, however, quantum computers have so far only been able to record a few dozen qubits. That’s why the new cryochip called Gooseberry is such a breakthrough.
“If the chip works as researchers propose and can be manufactured inexpensively, the design could simplify and accelerate the development of larger quantum systems,” said Charles King, principal analyst at Pund-IT, a technology consulting firm in Hayward, Calif., told TechNewsWorld.
EQUS Chief Investigator Professor David Reilly explained in a statement that to realize the potential of quantum computers, machines need to run thousands, if not millions, of qubits.
“The largest quantum computers in the world currently work with only about 50 qubits,” he continued. “This small scale is partly due to the limitations of the physical architecture that drives the qubits.”
“Our new chip breaks those limitations,” he asserted.
Freeze errors
Most quantum systems require qubits to operate at temperatures close to absolute zero (-273.15 degrees Celsius). This prevents them from losing their “quantumness,” the character of matter or light that quantum computers need to perform their specialized calculations.
“The environment can affect qubits quite a bit,” said Heather West, senior research analyst at IDC.
“If they’re influenced, bugs can be introduced,” she told TechNewsWorld. “By cooling the environment down to really cold temperatures, it helps eliminate bugs.”
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“The more qubits you have,” she continued, “the better your computer will perform. The problem is that qubits start working with each other — a process called entanglement — because they’re so unstable that they can start working incorrectly, or decoherently. As scale increases, decoherence increases.”
She added that there is another benefit of working close to absolute zero. “To reach supercold temperatures, you have to work in a vacuum, which helps reduce the environmental impact on the qubits,” she said.
Gilded Bird’s Nest
As with any computing device, quantum devices need instructions in order to do anything useful. That means sending and receiving electronic signals to and from the qubits. With the current quantum architecture, this requires a lot of wires.
“Current machines create a nice array of wires to drive the signals. They look like an upside down gilded bird’s nest or a chandelier,” Reilly said.
“They’re pretty, but basically impractical,” he continued. “This means that we cannot scale the machines to perform useful calculations. There is a real input-output bottleneck.”
With gooseberry, all wires are eliminated. “With just two wires carrying information as input, it can generate control signals for thousands of qubits,” Microsoft senior hardware engineer Kushal Das, a co-inventor of the chip, said in a statement.
Reilly compared the current state of quantum computing to the ENIAC state of computing in the 1940s, when a computer needed rooms with control systems to do anything useful.
“Our industry may face even greater challenges in taking quantum computing beyond the ENIAC phase,” Reilly said.
“We need to develop highly complex silicon chips that operate at 0.1 Kelvin,” he continued. “This is an environment 30 times colder than space.”
A true quantum control system
Operating at such low temperatures means the system must run on an incredibly low power budget, noted Sebastian Pauka, whose doctoral research at the University of Sydney served to connect quantum devices to the chip.
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“If we try to put more power into the system, we overheat the whole thing,” he said in a statement.
To achieve their result, the team built the most advanced integrated circuit to operate at cryogenic temperatures.
“We achieved this by designing a system that operates in close proximity to the qubits without disturbing their operation,” Reilly explained.
“Current control systems for qubits are meters away from what’s happening, so to speak,” he continued. “They exist mainly at room temperature.”
“In our system, we don’t have to leave the cryogenic platform,” he said. “The chip is right there with the qubits. This means less power and faster speeds. It’s a real control system for quantum technology.”
quantum computer race
King noted that quantum computing is still in its infancy. “We are still in the early stages of both building commercial quantum systems and programming and working with them,” he said.
“Some great things have been achieved, but there is still a long way to go before quantum computers become commercially viable,” he added.
Today’s quantum computers are mainly used to solve optimization problems. “These problems are found in almost every industry,” West said.
Hodan Omaar, a policy analyst at the Center for Data Innovation, a think tank that studies the intersection of data, technology and public policy in Washington, DC, noted that Japan is using quantum computers to optimize garbage collection.
Meanwhile, Volkswagen is using quantum computing to streamline the picking of parts for its cars. “They have shown that using a quantum computer is more cost-effective compared to a traditional computer,” she told TechNewsWorld.
“For a small set of applications – currently mostly optimization problems – quantum computers show that they can solve some types of problems better,” she said.
“As quantum computers improve,” West added, “they will be used to solve more advanced problems in fields like chemistry and pharmacy.”
“We still have a long way to go,” she continued, “but when we get there, we will solve a lot of different problems.”
One of those problems is already one nation competing against another.
“If a country can figure out how to build a quantum computer big enough and secure enough, it could be used to crack any encryption,” Omaar explained.
“That started a quantum computer race,” she said. “If you’re a country, you have to be in this race because if another country finds out first, you’ve got a big national security problem.”
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