Reading single electrons

2:23:25caveat though. It's kind of magical that we can even tell that there are two electrons in the room in the first place >> in the in the well, >> right? like what am I how am I how how do I tell >> if there's two electrons there or one electrons there right like I imagine again this is a solid state like piece of metal >> it's a piece of metal where we've confined it single electrons I need to know where the electrons are >> in a metal >> yeah sounds >> there's a lot of electrons everywhere >> I was going to say how yeah which one >> right like how how do I tell where the electron is and how many there are and so on and so forth Okay. So, to actually see the thing, I mean, we're talking

2:24:06about single electrons again, right? You can't use the resonant cavities and you can't use the lasers and all that other stuff. >> Oh, no lasers. >> Um, instead, we use something called a single electron transistor. This was one of the coolest things that I had to get used to um once I was like getting involved in this project. >> Single electron transistor. >> Yeah, it's such a cool sounding thing, right? >> Um, so here's how a normal transistor works. there's a source and a drain. And um if there's current flowing between the source and the drain, that's your one. And if the current is not flowing in your source and drain, that's a zero. And the way you make the current flow is you you um control the gate, the voltage on the gate, and you lower and lower the

2:24:47barrier. If you lower the barrier enough, there's a bunch of current. If you don't lower the barrier enough, there's a barrier, and it stops the current. That's how transistors work. >> Yeah. Yeah. Yeah. Now, there's going to be a point where you lower if you if you manufacture this stuff so cleanly and so closely such that there's a source electrode and a gate electrode that are right next to each other. Okay, maybe a few nanometers, tens of nanometers apart, okay? You've also got a little gate in the middle that controls that voltage. If you lower the gate just enough, single electrons are going to go through on the left hand side. Clever dog, I see

2:25:27it. Yep, I get it. Yeah, I get it. >> Basically, just creating a gap that's only the size of literally the shell of an electron. >> Yeah, this is a review paper [clears throat] that was actually written by um Michelle Devore, who is um one of the Nobel prizes >> last year. >> Yeah, that's quite nice. >> Um he he's been working in like quantum tech for a long time and he's saying, you know, you can amplify quantum signals using the single electron transistor. Here's the idea. If I've now got this sensor, this is effectively a sensor right? >> Right. I've got a little single electron transistor that is moving these electrons from one spot to another. >> If now I start changing the environment

2:26:08in my device, >> right? The rooms, let's say your hotel rooms >> are all on the let's say there's a lot the you know where the elevators are on the second floor, right? [clears throat] Let's say those elevators are where the single electron transistor is, >> right? You've got a source elevator and a drain elevator and you've got this like shuttling that's happening, [laughter] right? Um, if the rooms start moving around with electrons, >> the electron that is doing this single transistor effect is going to feel the effect because this is negatively charged and all the other electrons are close by and negatively charged. And if I can sense that

2:26:49>> very precisely, >> I can get little tiny deflections, little blips whenever the states in the rooms change. >> Yeah. >> Okay. So, by watching my single electron transistor very precisely, I can tell all of the stuff that is happening on the second floor. >> Would it be almost like hearing footsteps when you're in the elevator of someone running up and down the hallway? >> Kind of. Yeah. Yeah. Exactly. like you like the idea that you can sense at distance something that's happening from your single electron transistor which is this elevator shaft. Again trying to create a very crude analogy here but effectively >> effectively >> that's what we're trying to say is you can sense what's happening in these

2:27:29wells these potential wells at distance because the charge of what's happening in the wells will impact the electron gate that you have. >> Yeah. that you're sensitive to >> that that that you have is your sensor. >> Yeah, exactly. So, I've got a sensor right here and that's like got a little tiny bit of current that I'm sensitive to. And as the electrons move around in my device, this thing is going to start changing. >> It'll jiggle. >> It'll jiggle. And if I'm sensitive to that jiggle and I know my physics well enough about what each jiggle represents, I can tell what's happening everywhere. >> You can translate it into position of all of the >> Yeah. Okay. It's kind of when when I like first like got my hands on one of

2:28:10one of these devices and I was like, you know, I had a single like I made a call it a charge sensor or a single SCT. It's just it's so cool >> to think that that's what you're doing. >> Um it was one of those moments I think like in my life when I was like this is like really cool. >> That's really that's >> like I'm watching like single electrons move around from one compartment to the another on this nanop fabricated device >> that's been fabricated. >> Yeah. Yeah. It's it's it's really cool. I mean, it's like you're you're sensing quantum stuff. >> Yeah. >> Right. That's happening. >> Yeah. >> Yeah. >> I That's quite nice. >> It It was really cool. I still I I will never forget the day that I had my first uh sing. I made my first SCT and then I saw like my first tunneling event and

2:28:51things like that. It was It was really cool. Um >> so that's one way to implement it, which is in this case, every single electron that's in my checkerboard, eggshell, whatever you want to call it, is a single cubit, right? It's either spinning one way or it's spinning the other way based on a magnetic field. I talk to it based on microwave frequencies. Now that there's an argument to be made that like you don't want any microwaves >> whatsoever, right? Even [clears throat] you could have just a single microwave that's talking to these guys and then you can tune um all of them based on the single microwave. But what if you don't want any microwaves whatsoever? What if all I want to do is lower the

2:29:32barriers? >> Mhm. Okay, [clears throat] that's all I all I want to do is exchange >> open hotel room. >> Yeah, remember before the exchange was for two cubit gates. >> Yes. >> But in order to do one cubit flipping, I still needed the microwave and I still needed the magnetic field. What if I want to do everything based on just opening and closing doors? >> Mhm. [clears throat] Mhm.