3 ms·
Hey there. I happen to be lucky enough to work close to some of these beautiful machines; so I relayed your question along, and one of my coworkers produced thi
by mikewave 6y ago
Hey there. I happen to be lucky enough to work close to some of these beautiful machines; so I relayed your question along, and one of my coworkers produced this useful response for you:
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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%20T_jak%20dziala%20Triton/Priciples-of-dilution-refrigeration_v14.pdf 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 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 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.
- russol 6y agoThank you for the great explanation to you and your coworker! The documentation by Oxford Instruments and the tour are really cool. As far as I understand, almost the entire construction is a kind of a cooler. The actual quantum processor is located at the bottom of the upside-down pyramid. To make it work properly, the construction should be loaded through a ceiling to a special room with no air. It takes around 24 hours to meet working conditions. I'm still trying to guess what the rings on pipes are standing for? [1] [1] https://www.economist.com/sites/default/files/images/print-edition/20180818_WBP001_0.jpg https://www.economist.com/sites/default/files/images/print-e...