The exchange interaction

2:16:38>> Okay? It's just DC voltage where I'm like setting the voltage to this and then I'm moving. There's no oscillating stuff that's happening, right? when I want the electrons to talk to one another. And that exchange interaction is really um the way it works is it it sounds kind of like a magnet magnetism interaction like you know if you have two bar magnets that are aligned the same way they're going to kind of repel one another. Um quantum mechanically it's not really a magnetic interaction so much so as it's really electrostatics like the the electrons don't want to be next to each other cuz they're both negatively charged. And um there's a pi exclusion principle that's happening where if the

2:17:19two electrons are spinning in the same direction, if they have the same spin, they're not going to want to be close to one another. But if they're spinning in the opposite direction, they're okay being close to one another because they have opposite spins. And this is how the periodic table works. This is why there's two for every um energy state, any every angular momentum state. You can you know you populate it one this way and then you put the next electron in the down state. So one up state one down state and then you populate the the periodic table that way. In the same way even in these wells the electrons want to be close to one another only if they have opposite spin. If you have this in this hotel room analogy I don't mean to keep making this dumb but like if you

2:18:01have a a soccer tournament and you have two teams the door opens you have red team and blue team right? If the door opens between red team and blue team, they're not going to want to talk to each other because they're on opposite teams. But if you have between red team and red team, again, in this analogy, they're going to want to talk. >> It'll be somehow opposite because what I'm saying is the electrons are opposite. They want to talk to one another. >> So, fair enough. So, maybe they want to fight the red team and blue team. >> Everyone's Yeah. Everyone's Everyone's Everyone's agitated. They want to get So, and I know >> they'll keep their space if they're the same team. I'm mixing metaphors here because I know your point that you're saying that the the it's the positive or negative or the spin one versus another direction. And so if it's the same, they're not going to want to. And so in

2:18:41the analogy I'm talking about, you know, red and red and blue and blue are not going to want to. >> Uh but if they're opposite colors, they will want to exchange words. Banter say it's the banter uh the banter gate. Um, and so if they're opposite colors, they're going to want to um, uh, jaw at each other. But, but again, just to keep try to simplify that, >> there's the complexities about how those spin states exist. But the I think part of the point we're getting at is like we just just like every other system we've talked about, you have the the potential well has two uh, the the entanglement state has two this zero and one is very well defined.

2:19:22Yeah. >> By the dynamics of spin. Yes. >> In in these systems as is already exist and is well defined. >> Yes. Yeah. We we understand electrons and how they interact with one another very very well. And so if we can create these these electron wells where they're sitting and we can move them around in these wells and make make them talk to one another, >> we've got a very good handle on how these electrons will talk to one another, how those spins will change as they talk to one another and so on and so forth. Okay. Um how do we read them out? >> Okay. Right. >> Right. Uh like how do I tell if the electron is spinning one way or the other way? >> Because we know we understand how these things could but then how do we see that

2:20:02they are >> exactly like with the with the superconducting circuits there was a resonator that if it's in a zero or one it would resonate with that microwave cavity and then I'd be able to read it out whether it's one way or the other. Um with ions and with neutral atoms you basically just image them in some sense. You like use a laser and you try to image what the the light that comes out. Now, um, with spins there, it's a little bit tricky, right? Because I don't have direct access to which way they're spinning. >> Okay. >> But from the dynamics that I just told you >> Mhm. [clears throat] >> if they're both spinning in the same direction or if they're spinning in opposite directions, I'm using this very very colloquially in some sense because usually it's like there's um this the

2:20:45spin states are not like just straight this and this or this. Um there's combinations between them. There's something called the singlet state and the triplet state, which is the the spins going this way and this way. You either add them up or you subtract them. And those are the two states that are our zeros and ones. But the the dynamics that I told you earlier about why they how they they want to be together or not is still the same. If they're in the singlet state, then they have no problem being in a single spot. If they're in the triplet state, they have a problem being in the same spot. Okay? because of the poly exclusion principle >> is part of what you're saying that what puts them in the singlet or triplet state is there a lot of options. Yeah.

2:21:26>> There's a it's not just up or down. >> Yeah. >> But to simplify >> there's like two options but like it doesn't matter for this discussion. What matters is that those are the two states. >> Yes. >> And for the singlet state the the polyexclusion principle lets them hang out in the same spot >> but the [clears throat] triplet state it does not let them hang out in the same spot. So now what you can do is if I have two wells Yeah. And now I raise one of them so that I try to put both of the electrons in the same room. If they're in the singlet state, it's going to be way easier for them to get into the same room. But [clears throat] if they're in the triplet state, they're not going to want to get into the same room. Okay? It's going to take a lot more time. >> And if I sense >> whether there are two electrons or just

2:22:08one electron in that room that I tried to shove everyone in, >> then I've got a readout mechanism to tell whether I'm in the zero or the one, whether I'm in a singlet or a triplet. That's [clears throat] what's happening here. So on the on the top you've got kind of a triplet state in the sense that the electrons are not aligned and when I try to or they they are not aligned right and so in the singlet state when they're not aligned if I try to shove them into one it's allowed >> but if they're in the same >> then when I try to shove them it kind of gets blocked because the electrons don't want to talk to one another. And the point is, if I can tell what the charge is, if there's two electrons in that second room or just one, then I can tell whether it was in the zero or the or the

2:22:48one. And that's my readout mechanism. So, so you basically uh do something to change the environment. And then when you look at it, if the two electrons are together, then you know it's zero. If they're not, then you know it's a one. >> It's the to keep my annoying analogy together in the movie Inception when the the hotel room started rotating. when it started. If [snorts] it was sticking to the wall and refusing to go into the room when the whole was rotating rotating, >> you're you're in your one state here. >> Exactly. Um, now this introduces a