IBM ‘super-fridge’ aims to solve quantum computer cooling problem

IBM has ambitions to build a million-qubit quantum computer. To get there, it is building a fridge bigger than anything commercially available.
15 December 2020
  • IBM has set out a roadmap to develop larger qubit systems – from its current quantum computer of 64 qubits to a 1-million-qubit.
  • To move to a million-plus qubit machine, IBM is developing a dilution refrigerator, which would be larger than any currently available commercially

Say GoldenEye and the 1995 James Bond movie comes to mind, not a giant refrigerator.

But that’s the name computing giant IBM has given to a new refrigeration system in development designed to house the world’s first 1-million-qubit quantum computer.

At 10 feet tall and six feet wide, GoldenEye will go to a temperature of around 15 milli-kelvins or -459 Fahrenheit – or colder than outer space. These are the temperatures required to slow down the movement of atoms, so qubits can hold value. 

IBM’s director of quantum hardware system development, Jerry Chow, told Digital Trends that “for the quantum effects to emerge, [quantum computers] need to be cooled down to extremely low temperatures. In fact, all the infrastructure that goes around even just the processor itself requires a fair amount of cooling, especially as you scale it up, right?”

That said, such a scaling-up process had led Chow and his team to the inescapable conclusion that IBM really needed to get into the refrigeration business — at least when it comes to quantum computers.

There have been some creative solutions proposed for the quantum computer refrigeration problem, including the ‘nanofridge’, which works by tunneling single electrons through a 2 nm-thick insulator. By providing the electrons with too little energy to tunnel directly, the charged particles capture the remaining energy needed from the nearby quantum device, with the loss of energy consequently cooling the device.

Diamond has also been proposed as a more viable material than silicon for use within quantum computers, given its thermal conduction properties.

IBM’s quantum computing roadmap

To date, IBM’s largest quantum computer has 64 qubits. The company’s first step over 100 qubits is a 127-qubit IBM Quantum Eagle processor, which is due next year. This will be followed in 2022 by the 433-qubit IBM Quantum Osprey system, then the 1,221-qubit Quantum Condor system in 2023.

Vice-president of IBM Quantum Jay Gambetta, in a blog post, described how the roadmap for quantum computing would put IBM on a course towards a future million-plus qubit processor. This, he said, would involve industry-leading knowledge, multidisciplinary teams, and agile methodology to improve every element of quantum computer systems.

To move to a million-plus qubit machine – which is a pretty impressive leap from the current 64 qubits – IBM is developing a dilution refrigerator, which would be larger than any currently available commercially.

“The design principles established for our smaller processors will set us on a course to release a 433-qubit IBM Quantum Osprey system in 2022. More efficient and denser controls and cryogenic infrastructure will ensure that scaling up our processors doesn’t sacrifice the performance of our individual qubits, introduce further sources of noise, or take up too large a footprint,” Gambetta said in the post.

Discussing the work IBM is taking on to build a cooler for future iterations of its quantum computers, he said: “The 10ft tall and 6ft wide ‘super-fridge’ – internally codenamed Goldeneye – is a dilution refrigerator larger than any commercially available today. Our team has designed this behemoth with a million-qubit system in mind and has already begun fundamental feasibility tests.”

Ultimately, IBM envisions a future where quantum-interconnects link dilution refrigerators, each holding a million qubits like the intranet links supercomputing processors, creating a massive parallel quantum computer capable of changing the world.

Of course, setting out a roadmap to develop larger and larger qubit systems doesn’t exclude them from the problems that may come with it. Gambetta acknowledges the challenges the company is facing in building quantum computers. “Knowing the way forward doesn’t remove the obstacles; we face some of the biggest challenges in the history of technological progress. But, with our clear vision, a fault-tolerant quantum computer now feels like an achievable goal within the coming decade,” he wrote in the blog.