the methods required to maintain qubits are exotic.

this site mentions the refrigeration equipment youre referencing i believe https://www.pnnl.gov/news-media/new-superconducting-qubit-testbed-benefits-quantum-information-science-development

It’s not much to look at. Its case—the size of a pack of chewing gum--is connected to wires that transmit signals to a nearby panel of custom radiofrequency receivers. But most important, it’s nestled within a shiny gold cocoon called a dilution refrigerator and shielded from stray electrical signals. When the refrigerator is running, it is among the coldest places on Earth, so very close to absolute zero, less than 6 millikelvin (about −460 degrees F).

No one has given a real answer yet, and I’ve worked with these before, so I’ll explain. The short answer is it has to do with the logistics of cooling something to near absolute zero.

The main component of a quantum computer is a tiny microchip, maybe a few centimeters across. The big chandelier is for cooling and interacting with the quantum computer. (Compare to a desktop computer which has a small CPU chip but most of the computer is for cooling, powering, or otherwise supporting that CPU).

Towards the center of the chandelier thing there is a mechanism called a “dilution refrigerator” which uses weird properties of liquid helium to cool the quantum chip to about 15mK above absolute zero. There are often other refrigeration techniques at work and the dilution fridge does the last step of cooling.

The twisting golden tubes are microwave waveguides. Essentially they are wires that carry signals to and from the quantum computing chip. The twists are there because there is a lot of thermal contraction that happens when cooling from room temperature to near absolute zero, and the loops give the tubes some slack to contract.

Not shown in pictures as often because it’s less exciting, but the whole chandelier thing is put in a big metal cylinder, and that cylinder is within another cylinder, like a Russian nesting doll. Sometimes there may even be a 3rd layer. The air gets pumped out of the cylinders so it’s a vacuum inside. The multiple layers of cylinders are needed because the black body radiation from the outermost layer (which will be at room temperature) would be too much incoming energy to keep the qubits cold enough.

Also not shown is this whole thing is connected to an elaborate system of vacuum pumps, other refrigeration machines, usually a box of electronics for signal generation, and a classical computer (a standard desktop computer) used to control everything.

Note that not all quantum computer types use this kind of chandelier thing, only ones that need the near-absolute-zero temperature, such as superconducting qubits (trapped ion, neutral atom, and photonic quantum computers use very different setups).

Quantum states are incredibly fragile and can be disturbed with even the slightest interaction with the environment (called decoherence). These devices are cooled and isolated to the most extreme degrees possible and still at present decoherence severely limits the computations that can be performed.

Just wanted to mention at this point that the quantum computers in this post are the so-called superconducting quantum computers. There are also other architectures like ion and neutral atom quantum computers which are basically steel tubes with viewports that contain a ultra high vacuum. Lasers are used to control the ions or atoms.

There's also photon quantum computers, but they are even more different and not in a really advanced stage yet.

Because that's the cooling system required to run the thing. It requires more toxic coolant, that will eventually end up in the ocean, than several hundred supercomputer megaclusters and sucks more power than a thousand suburbs.

Wow so that's where they got the idea for the tardis engine

;)