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In the Hudson Valley, an hour鈥檚 train trip away from New York City, I am struggling to move a big, curved piece of metal. It is at the front of a large cylindrical machine at least twice my size. IBM physicist lends a helping hand and, together, we get it done. Closing the door of the world鈥檚 largest quantum computer fridge is no joke.

Quantum computing relies on keeping things cold. The quantum properties that make the components work disappear at temperatures as cold as just a few degrees kelvin (around -271掳C). The best fridges currently available can handle quantum computers with hundreds of quantum bits, or qubits 鈥� the basic quantum unit of memory. But to really start excelling over classical computers, quantum computers will need thousands of qubits. IBM wants to build one with 4000 qubits by 2025, which would be about 300 times more than its current biggest quantum computer. And for that, the team is going to need the massive fridge in front of me.

Gumann led . It is fondly nicknamed Goldeneye after the James Bond film and its interior can reach 25 millikelvin, about 100 times colder than outer space. The fridge is a cylinder 2 metres in diameter and about 4 metres tall, but much of that is taken up with the tech to keep it cool. I suspect that I could just about fit in the compartment slated for quantum computers, but I don鈥檛 dare for fear that the thin wires and gaskets won鈥檛 survive the interaction with my sneakers.

It took the team three years to build Goldeneye. Rather than requiring a huge conceptual leap, it was instead more about rethinking every small detail to take cooling technology to the extreme.

Take the metal components that are needed to move heat away from the centre of the fridge. They had to be made with extremely pure copper so they would be very efficient conductors of heat. But sufficiently good copper was only available in bricks from Germany. The team had to import it and find a specialist forge that could turn the parts into the right shapes. The fridge was a result of taking similar care with every component.

A household fridge cools by circulating a liquid refrigerant that turns from a liquid into a gas. This process of evaporation takes heat, resulting in an overall drop in temperature. Goldeneye does something similar, but rather than relying on the phase transition from a liquid to a gas, it instead transforms liquid helium into a series of exotic quantum states of matter, including a superfluid. This produces an even more powerful cooling effect.

To get a better look at where the action happens, I stand on a step ladder and peer from the top down into Goldeneye鈥檚 belly. There are five large, circular, evenly spaced metal plates 鈥� some of which are made from the German copper bricks 鈥� connected vertically by thin metal wires that the helium runs through. Each plate contains cooling components that take away increasingly more heat so that the one closest to the centre of the fridge is a thousand times cooler than the one at its top. At the bottom, another stack of metal plates will exactly mirror its top half.

Most commercially available fridges used for quantum computers open vertically, but had the team just scaled up that design, the fridge would have ended up tall enough to break the lab鈥檚 ceiling, says Gumann. The team put a lot of thought into avoiding this and came up with the door design that gave me trouble.

鈥淪ome people don鈥檛 really appreciate fridge building because they think it鈥檚 like plumbing, but you actually have to design it extremely carefully to get to low temperatures,鈥� says at Aalto University in Finland. He says that compared with the biggest fridges he has been able to buy for his own lab, Goldeneye has about ten times more space for chilling quantum processors.

鈥淔ridges are to quantum-computer engineers what space shuttles are to astronauts,鈥� he says. 鈥淭he larger, the further they can take you.鈥�

Back in May, after Goldeneye took about two weeks to reach its lowest temperature, the team placed a 10-qubit chip inside of it and performed diagnostic measurements to determine how well qubits would perform a calculation. These diagnostics showed that the chip worked perfectly well inside of Goldeneye.

Though Goldeneye will move to IBM鈥檚 new Quantum Data Center in Poughkeepsie, also in New York, later this year, the company鈥檚 quantum computers don鈥檛 yet require that much space. Goldeneye is aspirational, says Gumann. The many lessons the team learned by building it will be invaluable for improving smaller fridges too, he says.