Sarah
Hello, welcome to a new episode of our STEMterviews. Today we have with us Daisy Shearer from the University of Surrey, where she is currently undertaking her PhD project. And we’re gonna talk about physics and quantum technology today with her. Hi, Daisy, good to meet you. Good to have you with us today. First, would you mind summarizing your research project for us, please?
Daisy
Sure, so I’m a candidate in condensed physics at the University of Surrey. So my project is all about looking at a specific semiconductor called indium antimonide. And the thing about this semiconductor is it has what’s called a very large spin-orbit interaction. So that’s basically the interaction between the electron spin which is the intrinsic angular momentum of an electron, and the orbital angular momentum, the electron going around the nucleus. And this allows us to really look into using spin and like manipulating and controlling it for future technologies. So for example, quantum computing is kind of the big one. But also areas like quantum metrology, which is all about making really hyper-precise sort of measurement systems and sensors. So another aspect of my work is fabrication techniques. So I’m looking at what’s called a direct rate fabrication technique. Which basically means that you can put your sample in an all in situ, you can create different geometries and things. So I use a focused ion beam to do this, which basically shoots a beam of ions at the surface, and it can either kind of dig dig holes, or it can deposit material. And in that way, you can sort of either cut out different shapes. And you can also put new materials on top. And that’s how we can make these nanoscale devices. So I’m looking at specifically within dimentions to develop these techniques. And the lovely thing about the direct writing, is that you can really quickly prototype new devices. Whereas usually, these would take months to develop a new mask and go through sort of complicated fabrication techniques with the fair, but we can just in a day fabricating a new design, and then test it. So it’s really, really good for research and development, but not so much for commercialization, but in sort of the like, experimental side sort of research side of things. It can, like push us forwards a bit.
Sarah
So it’s a bit more basic, basic research focused. Yeah, okay. Yeah. Okay. So there was a lot of a lot of explanations, maybe we can just start, like from the basics. For what I remember from my physics classes, spins, there are these things that kind of exist, but also they don’t exist. And you maybe explain exactly what a spin is, especially in physics, because I have a chemical background, and I think there’s a bit of a difference with it. Enlighten me.
Daisy
So yeah, spin is a weird property. And we kind of physicists have kind of sort of deduce that it exists from experiments, things like the Stern–Gerlach experiment. And essentially, we think of it as the intrinsic angular momentum of an electron, because you can kind of have the analogy of in classical physics, if you had a rotating charged ball. It gives you an angular momentum. And it’s that angular momentum that we measure in our experiments. So we call it spin, even though electrons of course, aren’t actually little charged balls that are rotating around and rotating around. They are actually, we can think of them as probabilities and, and wave functions. But yeah, essentially, that’s kind of a good analogy for spin. And I still think about it in those terms, because it’s easy to conceptualize,
Sarah
Okay, so the spin is the, the property of the atom or of the electron because one atom is surrounded by many electrons, if I remember correctly, right? Each one has it has its own momentum has its own spin, right? And what does it have to do with waves?
Daisy
So yeah, it’s a it’s a property of particles in general. So each electron will have a spin number plus a half of minus a half. And yeah, I guess.
Sarah
Why halves?
Daisy
Because that’s how the maths works. Okay. In the case of electrons, it’s plus or minus a half, but other other particles have different spin numbers. But yeah, in terms of waves, in quantum mechanics, we often think of electrons as probability waves rather than like a physical particle.
Sarah
Wave. It is probable but maybe be not.
Daisy
Yeah, so you can think of it as, like, if you had a graph like this, like a bell curve. So of probabilities, we can describe electronics using this probability, sort of graph that, you know, they’re most likely to be at the peak and these likely to be out at the edges. But they can be in any of those places. And that’s kind of, it’s really hard to get your head around. And that’s like, what’s the mechanics, it’s kind of like, pretty foreign to a lot of people. But this is why we can get quantum tunneling, because say, you have your, your probability peak, and it sort of runs off and you have like a wall, quantum tunneling is there is a draw, and there’s going to be past the wall. And then if you have enough electrons, then that will happen.
Sarah
Okay, so that means, okay, wait, you have this probability curve, which means your electron can be somewhere within this area of the curve, right? And chances are higher that are in the the taller and bigger areas than in the outside. Okay. And each electron has to be within that. Yeah, chances are high probability is high that it’s within this area. Okay. So tunneling now means that there are chances that these electrons can also be outside?
Daisy
It just means in terms of like, if you have an energy barrier, that there’s a chance that it can, it can suddenly appear on the other side of the barrier. Yeah, it’s very difficult to kind of conceptualize as I say. But what you find is that this probability wave, we call it the wavefunction. Until we actually measure something interact with the system, we can treat it as if the electrons are in all of those probabilities at once, which is how we get some weird a wonderful quantum effects like quantum entanglement. And quantum superpositions.
Sarah
Okay, and what has this beautiful bell curve now to do with spins? And everything else? You said, basically?
Daisy
Well, essentially, when we’re thinking of an electron and electron spin, we can think of it in that classical way. But the reality is that it’s not a physical ball of charge, it’s it, we can actually describe it using this probability wave. And, yeah, the spin is just one property of the electron. But essentially, the reason why I bother the probability wave into it is that thinking of electrons in a classical way can be useful, but in terms of like applying it in a quantum technology kind of application, you can’t really think of it them in that classical sense, you have to dwelve over into this quantum quantum world.
Sarah
Okay. And how do you do that? How do you now use your spins for actual quantum technology?
Daisy
So what I’m working on at the moment is looking at kind of device called a spin polarizer. So, okay, yeah, I spoke a little bit about how you can have a plus a half or minus a half spin state, we call the spin up and down often with an electron. Spin. polarizer is essentially a theoretical device that when you pass a current of electrons through it, you can deflect one spin type in one direction and the other spin type in another direction.
Sarah
Okay, so it’s a bit like you have like positive and negative charge, and then you either get repulsion or adhesion.
Daisy
Yeah. And because it’s all related to the angular momentum and the associated magnetic moment, that’s we use a lot of magnets in my research, so yeah, essentially, I’m using these sort of rapid prototyping techniques to try and make a spin polarizer. And people have made them but not with what we call 100% fidelity, which means that 100% of the spin ups are going this way. And the other way, obviously, okay, we want to try and like maximize it as best as possible. And this can be used for sort of the main application would be initializing an electron spin qubit. So if you know that the this current is all spin up electrons, we know our initial state. Yeah. And that’s really key part of quantum bits or qubits in quantum computing, because if you don’t know your initial state, can’t possibly do any computation and read out. You have to know that that’s like the first step. In a quantum computation.
Sarah
I see it so yeah, okay, you’re trying to have like one population of electrons that all have the same properties and then go from there. Yeah. See? Yeah, exactly. See how they react? I got it. I got it. Okay. And okay, what? Okay, well, we’re just we’re talking of electrons, but electrons, are you only working with electrons? Are these electrons always part of an atom? Or an ion? That’s what I’m a bit confused about now. Because we know that atoms are made of electrons and protons. So yeah, where? Yeah, what exactly are you know separating?
Daisy
So I work with semiconductors. And essentially, we can think of this as in we can kind of flip between an insulator and a metal. So you know, in a metal, you kind of we call it a sea of electrons. So you have delocalized electrons that are bouncing around within your material. The same thing happens in a semiconductor.
Sarah
Which is shiny because they can reflect the light. That’s what I remember.
Daisy
Yeah, exactly, exactly. So within my semiconductor materials, electrons can move around freely under certain conditions. So that’s those are the electrons. And if we, we can make them flow like a current, like in a metal. So that’s what we’ll be looking at. They’re, they’re delocalized from their nuclei within the material. And we sort of look at them as rather than individuals. We look at them as a population flow.
Sarah
Yeah. Okay. Okay. That’s super cool. I think I think I’m getting it now, yes.
Daisy
Yeah? It takes asked away, it takes a lot to like, delve down into.
Sarah
Okay. Are we using this kind of technology somewhere in our daily devices, or like, the concept of this, the basic concept of this? I’m using.
Daisy
I mean, spintronics specifically not yet, there have been sort of prototype devices that have been made, but it all builds off of electronics, and semiconductors are what make up most of our electronics. So the transistor is a component that’s made of semiconductors and spintronics basically, is like we’re taking electronics, and we’re adding spin on top. So it all builds off of this background we have within electronics, it stands for spin transport electronics.
Sarah
Okay. Spin transport electronics. Okay, and what exactly is a semiconductor now?
Daisy
So semiconductors are a type of material that are between a conductor and an insulator. So if you think about an insulator, and we talk about the valence band and the conduction band, so the conduction band is the energies where electrons can flow around freely. And the valence band is where they’re, like trapped in atoms. So in an insulator, there’s a huge void called a band gap. So it would take electrons are lots of energy for them to leap from your bound valence band up into your conduction band where they can flow around, and you can measure a charge, okay, so that’s an insulator, the conductor is basically no band gap, it takes barely any energy and electrons are just inherently in that conduction band, semiconductors are in between, so they have an intermediate band gap. And that means that it can take very little energy for us to get an electron from that valence band into the conduction band. So for example, adding energy and we can shoot a photo now that shoot a laser. And we can excite an electron up into that conducting energy and then it can flow around. So that’s basically what semiconductors are. And these, the property of being able to kind of control how many electrons we can put up into that conducting state helps us sort of make devices like the transistor.
Sarah
Okay, and do you have some examples from our daily lives? With an insulator with a semiconductor and conducter, just for people to maybe guess, but a bit what, like, exciting and energy and what what is the energy? Where does that energy actually come from?
Daisy
So an insulator, I mean, something like wood would be an electrical insulator, so it’s very hard to pass a current through it because that, that the electrons are kind of bound. And yeah, it just, it doesn’t really have any electrical, what we call conductivity, okay, and a conductor example would be copper, you know, or any sort of metal that we use in electronics.
Sarah
I mean, but then wood is basically a chemical mixture of lots of different atoms and you know, chemicals and stuff. Well, copper is just one ion or like one atom, one chemical? Because you said wood as an example for an insulator? No? Okay. But in wood, you have like a different atoms, like you have carbon, you have hydrogen, you have whatever. So that’s why I mean, can you actually compare these things just because there’s different chemical backgrounds or then also different physical backgrounds? Because you know, the chemicals they are the atoms are bound to each other, which does that make make the electrons stuck with each other? So they can’t get excited to their higher state? Or is a property of an insulator? Or is it just one example?
Daisy
That’s just one example. Like, essentially, an insulator is anything where electrons can flow easily? I am going blank on other examples. Right now, unfortunately. But yeah, I mean, the classic conductor, all metals, and also wires and stuff.
Sarah
Okay, I gotcha, gotcha. Okay. So everything where we have electrons somehow free that it can get excited so they can slow and spin out to others.
Daisy
Yeah. And that you can pass a charge through it. With ease.
Sarah
Yes. Okay. Gotcha. Nice. That’s really exciting. So can you say, can you just maybe I’m really curious, like, how do you do experiments for your PhD? Is that truly theoretical, but that you’re then you also mentioned magnets, and you know, what is basically a normal day going for you in the lab, or at the computer?
Daisy
So I’m primarily an experimental physicist. And so I’m mostly in the lab, and I also dabble in the materials sort of engineering side of things these days. So yeah, there’s that. Sometimes I’m doing making those different geometries and stuff with new devices. But sort of the main bulk of my work is working with magnets and with sort of measuring the properties of my devices. So I work with a superconducting magnet. So it’s a big, dark green cylinder.
Sarah
How big? How big are we talking? A meter, two meters, three meters?
Daisy
With a meter and a half diameter. Oh, she’s pretty big.
Sarah
It is “she”! I love it!
Daisy
And it’s cool cryogenically cooled, so is liquid helium, to cool down on the magnet. So it’s made of superconductor. Yeah, another term, which is a material that’s like, when you cool it down far enough beyond what’s called its critical temperature, it goes into a superconducting phase, which means that a flow of electrons can flow through without any electrical resistance at all. So it means you can get a really, really large flow of current going through and because we can use a coil you remember from physics, a coil of wire can create a magnetic field around it. Yeah, yeah. So basically, for all magnets, she can go up to seven Tesla’s, which is more than sort of a MRI machine. But I have worked with a magnet that goes up to 15 Tesla’s and there are even 45 15 Tesla magnets, which is an incredible amount of magnetic field.
Sarah
Isn’t that a bit dangerous? Like, are you allowed to wear piercings or whatever?
Daisy
It’s, it’s, yeah, you’re allowed to go in within a certain distance of , yeah, like a pacemaker and stuff. Yeah. So risk assessed. So but yeah, there are, you know, risks associated with it. So essentially, this magnet, I’ll put my devices inside.
Sarah
Why a device now sorry, a device?
Daisy
A semiconductor. So like I say, a semiconductor I’ve made into a spin attempted to make a spin polarizer they are these. So the actual device would be nanoscale. But the, the chip that goes on, is probably about five millimeters, okay. And then, on the chip, we wire it up with really teeny, tiny golden wires, so that we can then measure electrical current across it and we can also put an electrical current through it. So once we put it inside the magnet, and we can then from the outside, we have a breakout box. That was one of the things I made early on in my PhD. You can wire it up in different ways and pass it pass currents through them and measure the because we mostly measure electrical properties to prove them. So then we’ll call it down to about four Kelvin usually is where I sit so really, really, really cold. And then apply electrical field. And what we find is that we can then prove the electrical properties. And that can reveal things about the spins. So the spin orbit coupling is something that we we look at and something called spin splitting. So essentially, when you apply a field, yeah, there’s so much jargon, I know, yeah, that’s fine. You get these peaks, and a, at a certain magnetic field, the peaks will start to split. And you can measure the amount of sort of double peaks that you get, and that that can tell you about the spin. And that what the electrons are doing energy wise within my semiconductor.
Sarah
Okay, so what are the waves, these waves are?
Daisy
So, flow? So, yeah, this, these would be like, basically, conductivity, so the amount of electrons flowing through.
Sarah
And they send it because at some point, they go, like, I don’t know, the maximum, they reach a maximum, and then something happens and they go down, or?
Daisy
So the spins, basically, it’s really difficult to go and…
Sarah
Try you’re doing better than you think.
Daisy
So how do I explain this? So there’s something called the quantum hall effect, okay. Which is basically a something that we observe in semiconductors, like the ones that I work with. And there, we find that as we increase the external magnetic field, that the resistance like, has these plateaus. And then we in one direction, so essentially, the geometry that we use is called a hall bar. So it’s kind of like a rectangle with two, four legs on it. Yeah. So if you apply a current across it, and then you can measure the voltage across waves and long waves. Yeah. And then this gives us these two, basically two different relationships that we find one of them is this plateauing. And the other one is that these oscillations that we see, which are those peaks, I was talking about that get that get split. And the really interesting thing about the quantum hall effect is that these plateaus and the corresponding peaks because the peaks happen in line with these plateaus. They’re consistent, so they can actually give us a, like a standard for measuring conductivity. Okay, gone off the deep end of it here.
Sarah
It’s all right. Yeah, so that is your baseline for everything else. Yeah. Okay. Okay. I get it. I think I do. More or less. Okay, so maybe we should switch the topic of it. Because we know that doing a PhD or beating academia for you is a bit more difficult bit more challenging than maybe for others. Can you maybe explain to us why that is? And yeah, what exactly are the challenges you’re facing? In academia?
Daisy
Yeah, sure, say, I am autistic. I was diagnosed when I was 21. So was not too long ago, cuz I’m 25 now, okay. And I find being autistic, quite disabling and identify as disabled. So that I have some, like, additional challenges associated with that, especially with the sensory environment and communication differences. And also sort of, in my home life, independent living and self care, they can be quite challenging and often I have to focus on that and then having the energy for my research.
Sarah
Yeah, okay.
Daisy
And everything else.
Sarah
Okay, and how was your supervisor supporting you with this?
Daisy
Um, he’s really great. Um, I didn’t disclose up front, but a few months in I did disclose him and sort of said, Me, by the way, I have this diagnosis. Yeah, kind of impacts the way that I interact. And he’s been really, really supportive and trying to understand that my mind slightly differently wired and also sort of coming to compromises and supposedly me and my reasonable adjustments. So I have access to a little private room that I can go to if I started to feel a sensory overwhelm, because we are based mostly in an open office. Okay, which is not a good environment for me, I’ve had several shutdowns up out in that. And so yeah, I had this adjustment where there’s this room I can go to, and I can switch off all the lights, and I can just self regulate again so that I can back out to work. Okay.
Sarah
And it’s really good to hear that this exists. I’ve honestly never heard of this. And I’m really happy and glad that you have this opportunity. That’s amazing. Yes.
Daisy
Yeah, I’m very thankful that I have that because otherwise I would not be as functional at all. Okay. So yeah, and we also sort of have some communication compromises. So from time to time, it’s very unpredictable, I will go nonverbal. And in those cases, we will do our one to one meetings using instant messaging. So things like that. And my, yeah, my supervisor and my university have been really, really supportive of me, which is great. But of course, there are always challenges. Like, you’re never going to get rid of some of the sort of broader systemic issues. And yeah, managing my needs can sometimes be a bit more difficult. But on the whole, like, yeah, had a lot of really great support.
Sarah
That’s good. That’s really good to hear. Okay. Especially since Yeah, academia and doing a PhD is, I think, more challenging than some others people’s journey through road life. So yeah, I’m really glad to hear that. And you’re also advocating for Autistics in STEM, if I remember correctly. What are your science communication projects involved in that regard?
Daisy
In terms of autism and stuff, I have a project called neuro divergent in STEM. So that’s all about connecting neurodivergent people, so neurodiversity, and kind of involves an umbrella of different conditions, autism being one of them, but also like ADHD, Tourette’s, dyslexia, dyspraxia, things like that, and people who have neurodevelopmental conditions. So I run this project that’s all about sharing the stories of different neurodivergent people’s paths in STEM, trying to provide role models for young people who are neurodivergent and might feel that they can’t see themselves in different STEM roles. And so, Yeah, we it’s were so inspiring reading all of the, like biographies that people submit, it’s community driven. So it’s all depends on people coming in close, because, you know, there’s never any pressure to disclose because it can be really challenging, and sometimes kind of dangerous to openly disclose. But for those who are happy with that, then then we share them and, and we also have a Facebook group and a LinkedIn group for people to join, if they identify as neurodivergent in STEM, and sort of making internal connections there and peer support and things like that.
Sarah
Nice. That’s amazing. Yes. Okay. And what do you feel most grateful for when people come to you and what? What, like, what makes you the happiest when they join your community? Or like, share experiences or want to help? What’s, what makes you the happiest and that moment?
Daisy
Probably people sharing experiences, and like the solidarity that comes with that, and seeing people like helping each other and sort of saying, oh, I’ve had a similar experience. Like for me, I’ve, a few people have said, Oh, I’ve had zero experience with this and that and it just makes you feel so much less alone. When there’s someone else going through it say.
Sarah
Yeah, that’s great. That was really interesting. That’s, that’s really amazing. Thank you. And at the end of our STEMterviews, you might have seen that we always have a couple of random questions. So the first one is, what was your favorite subject at school?
Daisy
My favorite subject in school, kind of it fluctuated between chemistry and physics. So yeah, I mean, by the time I was 15, it was quite securely physics. But yeah, I also liked art as well. That was kind of probably my third subject. Yeah, bit of a creative side as well.
Sarah
Okay, that’s good. I using it for anything. Like some science art? Are you drawing cool electron waves or something?
Daisy
I would love to like, once I finished my PhD and have more time. I really want to do some of that. But I think the creative it seems, like, being creative is a really key skill as a researcher and, that’s something that like, having that kind of creative side is really important and something I use every day.
Sarah
I couldn’t agree more. I feel exactly the same. Yeah. Okay, so in one sentence is that sentence? What are you truly passionate about?
Daisy
Helping people discover a passion for science.
Sarah
Nice. Nice. That’s amazing. And with you being here, you’re already doing a good job to achieve. That’s amazing. Okay, what do you do in your free time?
Daisy
I like to bake. And I’m also a gardener. So I do a lot of gardening actually did an outreach project called the quantum garden. So that kind of brought that together with those communications. So yeah, but baking and gardening and my main hobbies.
Sarah
Okay, what is a quantum garden? It sounds super fun.
Daisy
It was a little project that we ran, where, with my university, I kind of designed this little mini garden based off of a paper that some of my colleagues published a few years back. And it sort of tried to explore some quantum concepts like superposition and entanglement, like I was trying to find plants that were like, two, two of the same type. And then what in between that was meant to be like superposition things. And it was also shaped like a wave function with these sort of shells and stuff. And it was exploring different aspects of applications of quantum computing. So we had these little signs around that sort of explored potential applications. And it was in the local community. We put it out near where a lot of our students live out there. And it entered in the local gardening competition, and we won a gold medal and things. So it was basically just a fun little project to try and get the local community to engage with some of the research we’re doing at the university because a lot of them don’t know that. We have the Advanced Technology Institute, which is where I’m based and, and we’re doing quite a lot of exciting research there. So yeah, it was a really, really fun time.
Sarah
It sounds really cool. Yeah. Yeah. Nice. Okay, the next question is, what is your favorite movie, including quantum technology? Or does it not exist yet?
Daisy
Yeah, I’m not sure I’ve seen any movies. The thing about science and films is that often, yeah, it’s wrong. And it’s really annoying. So I’m not sure so…
Sarah
So superficial that it’s like, Man, I wish there was a tiny bit more explanation. Yeah.
Daisy
Yeah. So I’m not sure I have an answer to that one, to be honest.
Sarah
Okay. That’s fine. We could add that later. Yeah, I think. Okay. And then that last one is, what would you do if you were donated $10 million to your project.
Daisy
I’d like to set up the scholarship fund for disabled students to pursue STEM degrees and PhDs.
Sarah
Okay, that’s amazing. Yeah. I would love to give that money to you. Yes. Okay. Daisy, thank you so much for your time for answering all these questions has been absolutely amazing. I learned a lot about physics today. And yeah, a lot of my memory from physics and physical chemistry classes came back today. That was amazing. Thank you so much. And I hope you enjoyed it as well. And yeah, have a nice rest of the day. I guess.
Daisy
You too. Thanks for having me on. Thank you.
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