Materials, defects & tiny-scale imperfections as the enemy

1:18:34>> Yeah. Yeah. Exactly. But those guys had this problem of decoherence time. This new paper that's come out um in nature. >> Yes. >> Millisecond time scales. They're they're getting they're getting their stuff all the way to milliseconds. And this is a victory against the materials that we're using to actually create that transmon cubit. And this millisecond time scale is about three times the time scale that was there before the record. And it's 15 times what is the industry standard. >> Okay. Got it. >> Okay. It's very long. >> It is an order of magnitude. >> Order of magnitude >> um better improvement uh upscale. Got

1:19:15it. Okay. >> Exactly. Yeah. And what they're doing is they've the problem is, as I was saying, right, there's these tiny defects that happen everywhere else that sort of make my cubit forget what I am. If it's a zero, it'll just go halfway. If it's a one, it'll go halfway. Um, there's all these like glassy materials. There's oxides, there's substrates that happen when I construct my chip that is gonna that is going to make the decoherence happen. And so and just just to kind of zoom in on that point, the point is >> in the process of generating these chips, >> we have to make things at these incredibly small scales. >> Our engineering capabilities are quite

1:19:56good, but there are still levels of imperfection or just that the scales are so small that things tens of atoms, hundreds of atoms. So the slightest little thing um is going to again take our gate of our decoherence time and shrink it with any amount of >> 10 to the negative >> big number imperfection which is like barely anything. Yeah. >> Am I understand the quantum world >> it matters everything it's everything. Okay. >> You know. >> Yes. Yes. So that that's that is the one of the core sources of the decoherence time problem. >> Yeah. is all of these little

1:20:37imperfections that are coming in. And so there's been a history of trying to make things better, >> right? >> Okay. When it comes to getting longer and longer decoherence times, the first platform was to try and use nobbium and aluminum. Okay. >> The sapphire actually sapphire is just aluminum oxide >> and that was being used instead of nobbium in 2021 there was a breakthrough. The same group actually instead of nobbium they used tantelum. Okay. >> On the sapphire aluminum oxide. >> And there they got up to about 300 milliseconds. >> Okay. >> Okay. Sorry. 300 uh.3 milliseconds. So 300 microconds. Right.

1:21:19>> And then finally now they've challenged this bottleneck and instead of using sapphire they're using highresistance silicon. >> Okay. >> So extremely pure silicon that is high resistance. And what's happening is you're superconducting stuff that's happening in the cubit. It's no longer dissipating energy into the substrate itself because the substrate has such high resistance. One way to think about it is the energy just doesn't want to go there. Right. And so it's staying within the the cubit the the part of the circuit that actually matters. >> They they've locked down their border. >> Yes. Yes. In some sense. Exactly. That's

1:22:01exactly right. They've eliminated this bulk loss and using tantelum which is something that >> not a lot of people use but these guys were using it. Tantelum turns out to be much better than nobbium and aluminum. >> Okay. >> So it's this combination of tantelum and silicon and that was super non-trivial for them to actually grow because you've got silicon and you got tantelum on top. There's all this like chemistry that's happening that's like kind of weird. They had to use a really ultra high vacuum. Before they were using just high vacuum >> and it wasn't enough. >> It wasn't enough. Yeah. Yeah. So they had to use ultra high vacuum so that when they were depositing this stuff, no

1:22:42weird oil was getting in. Nothing like that. When it interacts with the air, nothing weird is happening. It it's it's it's been a process that's been happening for quite some time. But at the end of the day, they beat that millisecond barrier and they got to the key. The point is like they had to cook up like like Breaking Bad like like Heisen they had to cook up the the material that actually went into the the the thing itself the chip itself that is being now used to do this process. >> Yeah. Exactly. It's like completely novel. >> It's not like you can just go like hey Nvidia like hey you know TSMC and then let's just they were doing it. >> They had to which like I I want to like make that just >> like that's a big