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As a couple of people have already pointed out, the machine you're looking at isn't really the quantum computer, it's the apparatus that's used to keep the processor in a nice cold, quiet environment (a very necessary and complex endeavour when working with delicate quantum systems). Superconducting processors require dilution refrigeration, a process that uses the two common isotopes of helium to extract heat from the fridge and its payload (although other QC implementations may also require some cryogenics, the specific apparatuses may look quite different); Oxford Instruments (one of many commercial fridge manufacturers) has some relatively accessible documentation here: http://home.agh.edu.pl/~kozlow/fizyka/otrzymywanie%20niskich...
Gold is a commonly used material in cryogenics for a number of reasons: 1) it's soft and conducts heat really well, so by coating pieces made of other materials like copper with it and pressing them together, we can get good thermal contact; 2) it's shiny and doesn't oxidize so it reflects light really well since radiation (light) is another form of heat transfer, this again reduces heat absorption. Overall, material choice/design in cryogenics is complicated because many materials' properties change drastically at low temperatures (fun fact: dental floss is often used for this reason).
Depending on which images you're looking at, the "tubes" may indeed be coaxial cabling to carry microwave signals to the processor, but there are also tubes that act to circulate helium and as structural support of the various stages.
D-Wave's quantum annealing processor requires very few microwave signal lines, one of the reasons we've been able to scale it to over 5000 qubits.
For further exploration of quantum computing systems, I recommend this tour of D-Wave's lab: https://www.youtube.com/watch?v=VfxNdBTH8wY and this WebGL interactive 3-D tour showcasing the D-Wave Advantage processor: https://www.dwavesys.com/d-wave-advantage-showcase
I believe a new lab tour video is being produced right now and should be available soon, so check back on the youtube channel.