What does game development have in common with quantum physics? Take a listen to Episode 5 of insideQuantum to find out!

This week we’re featuring Dr Elliot Bentine, who was at the time of recording a senior postdoctoral researcher at the University of Oxford, an experimental researcher working with ultracold atomic gases, and in his spare time a video game developer. Dr Bentine did his undergraduate and postgraduate studies at the University of Oxford. He is the developer of ProPixeliser for the Unity game engine, and the AtomECS package for the simulation of ultracold atoms.

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🟢 Steven Thomson (00:06): Hi there and welcome to insideQuantum, the podcast telling the human stories behind the latest developments in quantum technologies. I’m Dr Steven Thomson and as usual, I’ll be your host for this episode.

In previous episodes, we’ve talked a bit about the theory behind quantum technologies and concepts like error correction and learning theory, but what are we actually applying these theories to? In order for them to be useful, we need to apply them to something in the real world, and that’s what we’re going to talk about in this episode. It’s a pleasure to be joined today by Dr. Elliot Bentine, a senior postdoctoral researcher at the University of Oxford who works on ultracold gases and in his spare time is also a programmer and video game developer. Elliot, thank you so much for joining us here today.

🟣 Elliot Bentine (00:48): Very nice to be here. Thank you for having me.

🟢 Steven Thomson (00:50): So before we get to the video games, which I’m sure people are desperate to hear more about, let’s first talk a bit about your career journey to this point, and let’s go right back to the start and ask what first got you interested in quantum physics.

🟣 Elliot Bentine (01:03): I think when I was very, very young…the backstory is, my grandfather, who I had a lot of respect for had basically been a very successful comedian in the UK. And he was quite, quite famous in his day and sort of show business. He was called Michael Bentine. He was a member of The Goons, which was a sort of famous British comedy group back in the fifties and sixties. But he’d actually originally wanted to go into physics and, and…He’d wanted to do that, and then I think that plan sort of got disrupted when the war had happened and he’d not been able to go to into university, but he, he was sort of…maintained that passion through life. And he had a lot of kind of physics textbooks. He had things like Einstein’s relativity, and electronics books and things like that in his library.

And I think one of my early memories when I was young was going into his study and looking at these books. And I, I think in a way I, you know, I sort of respected him. He died when I was very young when, I was about five or so. So I only have some memories of him. Very fond memories, but then in a way I sort of…I guess I felt that as I ead those books in his study, I kind of got to learn him a bit more that way and kind of saw another side to him that that was possibly less well known. And so, yeah, he, he had all these books on physics and I think that’s what kind of really kindled my interests in it.

He was always…he very much enjoyed making things as well. And I think I have a lot of fun memories of him when I was very, very young watching him making things. You know, I think originally he’d used that in comedy for making lots of different props and things like that, but, you know, he was very keen into, yeah, making all these cool contraptions and things, and that sort of inspired my interest when I was younger. And then from that, it’s sort of carried on. So when I was much younger I’d made sort of dangerous things in the garden. We made a sort of potato gun which was terrifying actually. We used to sort of fire kind of spears across the garden, basically. It used compressed air - we’d pump it up to about sort of 200 PSI or so and we had a sort of dowel that we tied a throwing knife to the end of it, and we could fire it about 30 feet and send it through a sort of that three inch thick wooden construction timber board.

So, yeah, that was, it was good fun.

🟢 Steven Thomson (03:19): So you were destined to be an experimental physicist from a young age then?

🟣 Elliot Bentine (03:22): Yeah. Yeah, I think, I mean, I was very lucky in that we had that stuff available as well. So, my dad works as a handyman and so he has a lot of tools around. He has a kind of workshop and, you know, effectively a space to make things and he’d make a lot of these things with me as well. And I think that definitely got me into it. And then I think the other thing which sort of helped was, was being into video games at a young age, because I think that’s actually how I originally got into programming, which has been very, very useful obviously throughout physics. You know, whether it’s for doing experimental controls to kind of, you know, bright timing systems and things like that, that we use for these experiments or, or whether it’s for, for instance, simulating some of the physical phenomena that we have to look at, which is, what we’ll talk about a bit later as well…sort of how some of that video game technology has made it into our research.

🟢 Steven Thomson (04:17): So you acquired all the skills from these various different sort of childhood experiences in your youth, and then was physics an obvious way that you could apply these and explore these skills in more detail?

🟣 Elliot Bentine (04:29): So I think it’s definitely like…I did also like the aspect of physics, which I think most physicists will say, which is kind of, you know, wanting to know how the universe works and, and, you know, trying to understand a bit better the universe around us. But I think also for me, it was very much skills based and that I did like doing these things. They were kind of hobbies as much as they were about personal development, in terms of learning how to do things and, and wanting to do cool things with it. And then physics just seemed like a very natural choice, because to be honest, when I got to the end of undergrad…if I’m honest, I hadn’t really enjoyed undergrad physics as much as I thought I would.

And then by the end of undergrad, I was pretty confident that I would be leaving physics, but then I went…in fourth year I basically went and did a project in, in the group where I am now with, with Chris Foot. And basically I really enjoyed the research. I hadn’t enjoyed the undergraduate teaching as much. I think probably because it didn’t really play to those skills as much. And then, once I started doing an undergraduate project, it was much more about kind of programming or making things. That was kind of much more in my comfort zone and also the things that I enjoyed a lot more. And so I thought, well, you know, this is what research is and this is what physics is and physics is gonna let me kind of play with all these cool things then yeah, I should give that a go. And so I went from there into then doing the…the PhD. And then since then, I guess the toys have gotten more expensive and more complicated. That’s kind of how I’ve ended up where I am.

🟢 Steven Thomson (06:03): It’s interesting that the undergrad degree almost put you off physics. I think I’ve heard quite a few people say that the research experience of physics is quite different to the undergrad learning experience and that it can be a difficult jump. It can be something quite difficult to adjust to when you’re sort of thrown into research and suddenly the questions don’t have nice, neat textbook answers. And sometimes the questions are not even particularly well defined in the first place. You know, finding the question, I guess, is the first step of research as opposed to the undergrad experience where normally, you know what the question is, the task is to find the answer.

🟣 Elliot Bentine (06:37): I think for me, it was fortunate in that I went from liking undergraduate physics less to liking postgraduate physics more, but I’m fully aware that there are many people where that’s the other way around. They’ve basically gone from loving undergraduate physics and loving, you know, the way physics is presented there to then absolutely hating research. In a way it must be a shortcoming of…basically the undergraduate physics course is not preparing people properly for what research is. And I think, or at least I hope…I know there was this push recently to move to this kind of CDT model where the way it used to be is that you’d go from your undergrad and then you’d basically get plunged into the deep end of the PhD project. And I think now they try and encourage people to do something that’s more like you, you do your undergraduate and then you do effectively like a year masters project where you can test the waters of research, you get a feel for the group and sort of what the research will be like. And then there’s still time at the end of that to effectively make a change or, you know, change group or change project or, or, you know, decide altogether that you don’t want to do a PhD. Because, you know, I think it isn’t something that everyone will enjoy basically, and people should be able to leave if they don’t like it and also still get something for their efforts so far.

🟢 Steven Thomson (07:54): Yeah, absolutely. In fact, I came through a CDT. That’s where I got my PhD and it’s something I’ve always been curious about is to see after, I dunno, five years, ten years, how does that compare to the more traditional PhDs, you know, where are people? Are people in research, are people in industry, are they still using these skills or have they gone into a completely different field? I think it would be really interesting to see after some time has passed, you know, what proportion of people in academia came through CDTs and is it any higher than from the traditional model - but I guess probably not enough time has passed since CDTs became a thing to really answer that question.

🟣 Elliot Bentine (08:31): I wonder if there’s a sort of good…because also the other thing is like the whole purpose of PhDs shouldn’t necessarily be to produce academics as well. I think it…you know, if we’re gonna assess it, how successful that is, we need to kind of figure out…you know, I think probably the answers should, should like, do people enjoy doing it that way more than they used to enjoy the other way? Maybe some people end up just going into to industry afterwards and you know, that’s a perfectly valid route as well.

🟢 Steven Thomson (08:58): This is true. In fact, the CDT, I was part of had a very strong focus on industrial placements and giving people the opportunity to…yeah, to get some experience outside of academia, in a variety of different companies and just, yeah, explore your options. You could take a few months of just…you can put your PhD on pause essentially for a few months, go work for patent lawyer, go work for a technology company, go work for anything that you liked and then just what, what worked for you. Yeah, it was an interesting scheme. I have to admit, I didn’t really take advantage of that myself at the time.

🟣 Elliot Bentine (09:28): Another area where I feel that it should be easier to try out when you are doing a PhD would be something like policy. Because obviously I dunno, I feel at the moment that scientists are quite underrepresented in policy making decisions. I think- isn’t there some statistic about the number of members of parliament in the UK who actually hold like a science A level? I think it’s something like four MPs or something like that. It’s just like, oh…

🟢 Steven Thomson (09:55): Wow, it’s really that low?

🟣 Elliot Bentine (09:56): Yeah. I can’t remember what the exact number is, but I do remember reading it and thinking like, wow, that’s…that’s, that’s actually quite frightening. And I guess, you know, especially with things like academia, it…people always say it’s kind of a one way door as well. Like if you get off the train at any point, you know, at any point in the journey, it’ll sort of leave without you. I don’t actually think that that’s true. I think these days there’s a lot more ability to go back and forth between these things.

🟢 Steven Thomson (10:22): I certainly get that impression. Yeah.

🟣 Elliot Bentine (10:23): Yeah. Be interested to see if…if there’s a better way to get people in PhD programs to actually take part in policy making processes, things like that.

🟢 Steven Thomson (10:34): Yeah. I think a large part of that also is knowing the options that are available to you. And I think as time goes on, we’re more aware that a PhD is not a…it’s not like a death sentence to do research for the forever. You can leave and do different things. And even within a PhD, I guess, or within a research career, you still have quite some freedom to change fields and experiment a bit, which I think we’ll talk about a bit later when we get onto some of your work, So, okay. We’ve talked there about different career options. So let me also ask you, if you had not gone down the research route and you were not a postdoctoral researcher, what do you think you would’ve done instead?

🟣 Elliot Bentine (11:13): I genuinely dunno to be honest. I probably would’ve gone into programming. Just based on the fact that…so in my undergrad, I’d done some sort of internships at software companies. I like programming a lot. I think, yeah, probably I would’ve gone down something like enterprise programming. I had sort of friends and contacts, particularly from the open source community and various projects I’d been in when I was back in school who went on to go and, you know, take up probably much better paid programming jobs , and they seem to work much, much healthier hours than we do in research. So yeah, maybe would’ve done that.

🟢 Steven Thomson (11:53): Okay. So can you tell us perhaps a little bit about the field that you work in? So you’re an experimental physicist, the first experimental physicist who we’ve had on the podcast and you work in the field of ultracold quantum gases. Can you tell us a bit about what are ultracold atoms and why are they interesting? What kind of challenges can they be used to address?

🟣 Elliot Bentine (12:14): Okay, so ultracold atoms, obviously the, the most obvious thing in the name is the cold temperature. And I guess, firstly, we should ask, why do we need to have things that are so cold in the first place? The kind of physics that we are interested in is predominantly quantum mechanics and the reason that we want to go so cold is basically that, in quantum mechanics you have this quantisation of the energy levels of the system. And obviously that’s a true behavior of the universe all around us, it’s just that normally the splittings of those energy levels are so small that the energy scales we are used to in a classical world…we can’t resolve them. It’s like the graduations on a ruler are too fine for us to see. So what we do is we make the temperatures much, much colder and in doing so, what we’re really doing is reducing the energies in the system - the characteristic energies that are involved - until our system then reaches a state where those energies are comparable to the splittings so that we can begin to make out the types of changes in behavior that occur when something is dictated by quantum mechanics, rather than by classical physics.

🟢 Steven Thomson (13:20): So how cold are we talking here? How cold is ultra cold?

🟣 Elliot Bentine (13:23): So ultimately we’re going down to, depending on the type of experiment you want to do, maybe 10 nanokelvin or colder. It’s quite hard to picture what these temperature scales are. I think probably, you know, if you think of what the hottest thing is, probably most people would say the sun, and the sun has a surface temperature of about 6,000 Kelvin. And then room temperature is 300 Kelvin or so, so really to go from room temperature to the sun, you are really only going up kind of like one or two orders of magnitude. So when we then say, we are working at, you know, 10 to the minus eight Kelvin and room temperatures are ten to the two Kelvin. So you go from room temperature to the sun and that’s two orders of magnitude. And then, you know, we are going kind of like 10 orders of magnitude colder. So, that puts into perspective really just how cold we have to go. I think if you ask most people “What is the coldest thing that you can imagine?” I think almost all of them will probably say…well, I think a lot of people would say liquid nitrogen, that’s like, what, 70 Kelvin, I think, and then liquid helium, which is like four Kelvin. And then people might say outer space or so, and outer space is…what is it, a millikelvin?

🟢 Steven Thomson (14:35): It’s, I think…isn’t it 2.73? [Ed Note: Steven’s undergraduate degree was originally astrophysics…!]

🟣 Elliot Bentine (14:37): Ah, 2.7. Okay. So that’s hot, really hot. That’s basically sort of summer holiday. So yeah, so we’re substantially colder. And then, the question is…so that’s sort of the “why” - you wan to get cold enough so that you are able to make out these laws of quantum mechanics, and then you can push and you can probe your system and and you can watch how it responds. And that’s kind of the general idea behind quantum simulation - it’s that you are making your system look like something else dominated by quantum mechanics. And then you’re sort of seeing how it would react to solve a problem that that would be intractable. Otherwise, you know, you couldn’t necessarily sit down and work out that theory for it. The other reason you want to go very cold is because when you’re very, very cold, your environment is very quiet.

And so when you are very, very cold and you have these kind of systems dictated by quantum mechanics, you can then make very accurate measurements of things, be it time or magnetic fields. And so then that’s also the whole field of quantum sensing as well comes out of that. So that’s the kind of “why”. And then the how - we use predominantly two techniques that are used to get down to very, very cold temperatures. The first one is laser cooling, which is almost certainly the first stage that people use to get to those temperatures. And that might sound like it’s slightly paradoxical because most people would associate lasers with heating things up. You know, it’s a stream of energy. You have this kind of bombardment of photons, and each photon’s carrying some energy with it.

So you’d expect that might cause your thing to heat up. But in laser cooling, you are using the fact that each of those photon carries momentum as well. And so you arrange your system so that each atom is absorbing photons traveling in a direction opposite to it. So actually that absorption of the photons acts to slow the atom down. As it sort of takes that momentum from the photon, it’s decreasing the velocity of the atom. And so you can use that to reduce the temperatures of your atoms. You can only use laser cooling to go so far, but laser cooling is very effective and is more or less the starting point for all of these experiments. And then the way you go down to the absolute cold temperatures tends to be in most labs a method called evaporative cooling.

And what you’re doing in evaporative cooling is very similar to how you would cool down a cup of coffee…if when you have your cup of coffee, you blow on the top of it, for instance, by blowing on it, you are removing the atoms with the highest energy that are able to sort of momentarily break out of the surface of the coffee and your breath then sweeps them away. And by removing the atoms which have greater than average energy, the atoms that remain must then have less average energy than the average energy of your entire atoms beforehand. And so by doing this process again, and again, kind of cutting away the sort of highest energy atoms and letting the remaining atoms thermalise, you can basically act to sort of reduce the temperature of your system. And so that’s how we can take our atoms all the way down to kind of tens of nanokelvin.

🟢 Steven Thomson (17:26): So you’re cooling atoms down to temperatures colder than space, I guess - temperatures that are probably not found naturally anywhere in the universe, as far as we know.

🟣 Elliot Bentine (17:36): Yeah.

🟢 Steven Thomson (17:36): And you’re doing this so that you can study this kind of very quantum regime where there’s no thermal fluctuations, nothing else. There’s only…quantum mechanics is the only game in town. And you have this very kind of clean system where you can study sort of quantum phenomena that are very difficult to access in other ways. Is that a fair summary?

🟣 Elliot Bentine (17:55): Yeah, exactly.

🟢 Steven Thomson (17:56): Okay. Interesting. And you mentioned there are a couple of different applications. So in previous episodes of this podcast, we’ve talked about quantum computing and how you can use certain experimental setups to act as quantum computers, but you mentioned a very different application in there of quantum sensing. What’s the advantage of having quantum mechanics in a measurement device?

🟣 Elliot Bentine (18:19): So I guess there’s two separate aspects to it. One is that when you’re looking at the level of individual atoms quantum mechanics is present in almost every part of…what you can do with those atoms. For instance, quantum mechanics will be present in determining the energy level structure. That then dictates how you can interact with the atom, whether you can use magnetic fields to perturb the atom or optical fields, what kinds of fields you can use, you know, whether the different polarizations or frequencies they are, et cetera. So I think one part of it is that the atoms have a very high degree of sensitivity to external fields, depending on whichever state they may be, because you have an ability to measure, for instance, the energy separation between two energy levels to a very high degree of precision. If an external field were to change that energy level separation, it would allow you to basically determine that to a high degree of accuracy. What that external field is…because effectively you have a way to, you know, if you can very accurately measure what this separation is, you can then look for very small deviations in it. And therefore that gives you a very, very precise ability to determine what the external field is.

🟢 Steven Thomson (19:32): I see. So because these atoms are so cold and so well controlled, you can characterize them really well. You know in quite a lot of detail all the properties of these atoms and that lets you watch for when these properties are changed and you can measure these changes. And this is why cold quantum matter can be used for very precise sensors then?

🟣 Elliot Bentine (19:54): Well, so yes, so that’s kind of one part of the story. And then the other part is that you can…there are several specifically quantum mechanical effects that you can use to also perform precision measurements, you know, in a slightly different way. So, so one is almost like the precision and control that you have over these systems to then measure these energy levels very precisely. And the other way is that you can use…so for instance, you can use quantum effects like interference. You can take an atom, you can put it into a superposition. And then when, so when your two different states are then affected differently by some external field - you know, you separate your two states, some external field changes the energy of these two states in a different way. You sort of let time do its thing for a little while, and then you bring the states back together that then produces a kind of differential signal that, that you can can measure. So you’re looking for, you know, at an interference signal that you can measure very precisely.

🟢 Steven Thomson (20:52): I see. So by comparing these two different atoms, these two different copies of your system…by comparing them and by, I guess, physically moving them on top of each other and looking for interference effects…this gives you another way to really accurately probe any changes that have been made.

🟣 Elliot Bentine (21:09): So I guess I should rephrase it slightly in that it doesn’t necessarily have to be a spatial separation. It depends what kind of field you’re looking for. So for instance, if you were wanting to measure a magnetic field, you might actually want to keep the two different states of your interferometer at the same location, but just have one of them sensitive to the magnetic field. And one of them not. So then when the magnetic field is applied, you get some energy splitting between them. Then you bring them back together and you look at your differential signal. If you wanted to measure, say like rotation, for instance then you’d need to send…you’d need to find a way of separating your states in space so that they could, you know…maybe you send them round a ring in two different directions so that when your ring is rotating, one of them has traveled further than the other has traveled. And then that would be the path length difference that the produces a signal in your interferometer.

🟢 Steven Thomson (22:00): So you mentioned there the word interferometer a couple of times. So that’s a device that uses interference to make measurements. Can you give us any examples of use cases of interferometers - either historical uses or more modern cutting edge uses?

🟣 Elliot Bentine (22:14): So I think the most…probably the most well known interferometer is the Michelson-Morley interferometer. Historically…It’s a very simple device. You have, you know, effectively a beam comes in from the bottom. You have a beam splitter, you send your beams down two directions, your sort of two different paths and you reflect them off mirrors, and then you bring them back to the beam splitter, and then you send them off to a detector. And then what, what I think Michelson and Morley were trying to measure was whether or not there was a sort of ether, like, was there a…a stuff that we were moving through, some sort of absolute reference frame of the universe, so that then if your interferometer was moving you might see one of the lengths kind of change compared to the other one, but they didn’t see that . So, then that was, I guess, quite an important proof of relativity - the idea that all inertial frames were equivalent to each other.

🟢 Steven Thomson (23:06): So the idea of it is you split a beam of light in two, you let the two paths do their thing, you recombine them. And then you’re looking to see, is there some difference between the two paths and that tells you that they’ve been affected differently. And in the case of this experiment, that would tell them something about what the universal was made of and if there was an ether.

🟣 Elliot Bentine (23:25): Yeah. And so I think it’s probably worth mentioning that, that, you know, one of the projects that was more recently working on is AION, which is this UK attempt to build a sort of large scale atom interferometer that can look for things like gravitational waves and dark matter. And then what AION wants to do…AION is not a traditional interferometer in the normal sense. It’s actually more equivalent to using the precision measurement techniques of optical clocks as a way to time how long it takes for a laser pulse to travel between two test masses. The test masses are individual atomic clouds that are freely falling. So it does use interferometry, but it’s slightly different to the normal case. What it means is that you can use the techniques developed for measuring time very precisely to now measure a length very precisely. And then if a gravitational wave travels through your device, there’s a very slight fluctuation in this distance. And so what you are really doing then is using the timing of these pulses to precisely measure the small contractions of that space so that you can then measure the passing of your gravitational wave going through the device.

🟢 Steven Thomson (24:33): I see. Okay. So the idea then is you have these two clouds of cold atoms that are separated in space. You’re using lasers to measure very precisely the separation of these two things. And if a gravitational wave comes by, that changes the separation. I guess the two clouds will wobble in space.

🟣 Elliot Bentine (24:51): Yeah, they’ll move, they’ll move up and down slightly, for instance. And so you look at that kind of very subtle contraction of their separation, right.

🟢 Steven Thomson (24:59): Okay. That’s interesting because if I think about gravitational wave detectors, like LIGO or Virgo, these, these reasonably well known big experiments…these are BIG experiments, right? These are, what, tens…hundreds of kilometers long? These are very, very large scale experiments. What kind of size of an experiment do you need to do this with an atom interferometer? Do you also need to have these clouds of atoms separated by tens of kilometers? Or is this something you can do in a single room in a lab?

🟣 Elliot Bentine (25:32): So the kind of threshold length I believe where you can start to look at gravitational waves is when it reaches round about a hundred meters or so.I believe it’s because your kind of characteristic wave length for a matter is actually much smaller than that for light. And so, as a result, you know, you need a much smaller length scale to observe the same change.

🟢 Steven Thomson (25:53): Right. So you don’t need an experiment to quite as large as these light based enterers then in, in principle, these atom ones could be much more compact.

🟣 Elliot Bentine (26:02): But it’s interesting - the comparisons between the two types of technology are actually not necessarily as straightforward. So basically each type of device has a sensitivity that falls in a different frequency range. And so AION, and other kind of atom interferometers would be sensitive to the what’s called the mid band frequency. So worth also mentioning there is a project in the US, MAGIS, which is sort of leading the way or much of this, which AION is kind of collaborating with.

🟢 Steven Thomson (26:30): I see. So these are, these are complimentary to the existing gravitational wave systems. They’re not a replacement.

🟣 Elliot Bentine (26:37): Yeah, exactly. I think obviously that works out nicely in that it feels like everyone can win.

🟢 Steven Thomson (26:44): . Yeah. Okay, nice. That covers some of the cold atoms aspects of what you work on. But at the top of the episode, we mentioned a bit about video games. We mentioned this a few times, so let’s come back to this now. Outside of your day job as a postdoc, you’re also a video game developer. How did this come about? How do you have the time?

🟣 Elliot Bentine (27:05): I guess the thing is, it truly is a hobby. I mean, it’s something that I enjoy doing very greatly. So, you know, it’s quite nice to do it in an evening. There’s a very creative part to video game development as well, particularly things like graphics programming, because…and, you know, also quite a lot of overlap, to be honest with atomic and laser physics, you know, atomic and laser physics is all about the interaction of atoms with light, and matter with light. And you have to think a lot about how that sometimes gives rise to different optical properties as well. When you do graphics programming, what you are really writing is ways to determine the color of pixels on the screen, based on things like, you know, the normal of some mesh, you know, the direction it’s facing, the way the light’s illuminating it, what it’s made of. And obviously these are all kind of…what you’re really doing is finding ways to approximate how that should look because the real world around us, you know, and the colors we see and the types of phenomena we observe, they’re made up of a very great number of different aspects. So if you think of, for instance, water, you know, the sun reflecting off the sea, there’s a lot going on. There, there’s things like sub scattering of the…you know, the sun’s rays hit the water, they go under the water a bit, there’s then sort of random directional scattering. And then some of it comes back up. There’s also the fact that different polarizations will reflect differently. You then have the kind of rippling surface of the water. So, you know, some parts will be bright, some parts will be dark. You might have things like foam and surf on the, on the surface of the water.

Maybe now your water isn’t water, maybe it’s oil. And so you have a sort of iridescent…so kind of, you know, colorful rainbow that you see on the edge of the oil, all of these things, you know, if you kind of think of them, even at a sort of undergraduate level of physics, you might be able to work out where some of these individual things come from. And so when you’re writing graphics shaders, you’re kind of adding more and more of these approximations to better approximate the behavior that you want to reproduce, but to do it at a really fast frame rate, because when you’re doing graphics programming, it all comes down to the fact that ultimately your programs have to be fast because they need to render it to the screen multiple times a second. You know, you have to run these programs sometimes for millions of pixels and they need to be done, you know, in a way that you get that nice smooth sort of 120 frames per second gaming that people expect these days.

So there is a lot of overlap in, in the sense that it’s, you know, there’s physics you have to think about sometimes. There’s a lot of mathematics as well. There’s also kind of high performance programming techniques. And yeah, personally I enjoyed a lot. So, I was sort of doing that just for fun anyway and then I joined the kind of Oxford Indies - they’re a kind of group of independent developers in Oxford. And so I joined them and sort of went along and kind of met them for a few different lunches and things and Tim Watts, who I’ve become very good friends with basically said to me , “You know, this particular one you’re working on…” which was a sort of set of shaders to, to render a 3d object, to look as if it’s a 2d sprite - it’s just like a very stylized graphical style that happens to be quite popular at the moment. And he sort of said, “Oh, you should, you should look into selling that”. And so he convinced me to sort of pursue putting it onto the Unity asset store. So Unity is a big game engine. I think something like 70% of all games are now made in Unity. So it’s got a very large number of users, extremely popular resource and it has an asset store. So you can basically upload things and then sell them. Unity obviously takes some royalty on that, but it has a great many users. And so he sort of convinced me to do that. And I’m very glad I did. So it’s, yeah, selling quite well.

🟢 Steven Thomson (30:50): It’s interesting that you mentioned the performance aspects actually, because in science, I guess that’s not something we really have to contend with in the same way. I suppose that you want your simulations to run in a reasonable timeframe or if you have access to some kind of national cluster computer, maybe you have a few hundred thousand hours and you’ve got to get your code to run in those few hundred thousand hours, but that’s different to, to video games where you’ve got, what is it, something like 33 milliseconds to target a playable frame rate, something like this?

🟣 Elliot Bentine (31:19): Even less now cause people are, I mean, people get incredibly fussy

🟢 Steven Thomson (31:23): Yeah. So I guess there’s some really different pressures and different things you have to think about when coding a game when you’re talking about performance. It’s really how quickly can you draw this frame and get it on screen, as opposed to how accurately can I compute this quantum phenomenon? There’s some trade off between how realistic do I want it versus how long is it gonna take to render this scene? Okay. So we’ve talked a bit about your interest in games as well as your interest in science, but you’ve also managed to combine these two. Can you tell us a bit about how game engines can be used to demonstrate and to teach some aspects of quantum physics?

🟣 Elliot Bentine (32:05): So, yeah, so it…I have a lot of respect for the kinds of technologies that go into modern game engines. So a lot of these are now very, very well engineered pieces of software…that hopefully isn’t too surprising, because they’re worked on by sort of thousands of people at a time now. And you know, the kinds of tasks they have to do are very computationally intense. There’s the graphics rendering side, which I I’ve said a little bit about, but there’s also usually a whole host of other calculations that are going on under the surface to sort of determine how the game should play. And so one of the patterns which has become particularly popular in video games recently is a particular architectural pattern called Entity Component System. So we’ve used this particular approach to great effect in some software that we’ve written recently for sort of doing simulations in ultracold atoms.

Ultimately we’d like to use this for outreach as well as for research, but our main reason for writing this software was actually for the research side. So the reasons we decided to use this particular pattern is because it’s really highly performant. As I said, one thing is that you can write this code and it can run in parallel very easily. And it’s also very modular and kind of easy to extend and easy to test it. And obviously if we are writing code, that’s used to research, it’s very important that we know that it gives the right answers. And so that…I put a lot of value in us being able to write tests very easily to verify that individual core components of this software are doing what we would like them to do. And so we, we wrote this code called AtomECS.

So, I did this in collaboration with Dr. Tiffany Harte who’s over in Cambridge and we had to students that we worked with as well for this and we basically used this to, to simulate a variety of different cold atom systems now. So we were sort of building this up to be a kind of general purpose cold atoms research code. So we do it for things like simulating the laser cooling processes for the atom sources and AION, also things for, you know, simulating the transport of cold atoms in optical traps for simulating the evaporative cooling of atoms. So there’s a whole host of problems that we can look at using this code. One of the very nice things is that because we are using a pattern from video game development, we’re also then very easily able to integrate it into sort of existing video game software ecosystems.

And what that’s given us for free basically is the ability to then use the rendering software from video games to make very nice demonstrations of this physics, and even cooler, we can actually compile it for web as well. So hopefully we can, we can add a link to, you know, at the end of the podcast to, to one such demo, which is sort of showing how the laser cooling source works for AION. So it’s a demo that shows basically an oven, which is emitting a bunch of strontium atoms, and then those atoms interact with some sort of cross diagonal laser cooling beams, the atoms are slowed down and then a third beam kind of pushes them out of the chamber. And what I would really like to do is, is see multiple of these demos made, you know, ideally I’d, I’d go around and collect all the CAD files from, from different PIs and see which of them want you know, a sort of demo of their apparatus made.

Because I think it would be a really good opportunity for sort of teaching and outreach. You know, I think it would give hopefully people a bit more of kind of intuitive feel for what’s going on in these experiments. Cause I think when someone looks at, at these kind of cold atom apparatus, they can be quite daunting, you know…they’re large pieces of vacuum apparatus with lots of sort of windows, lots of beams going everywhere. And it’s, it can be quite hard at first to disentangle what each of those beams is doing. But hopefully if you’ve got some demo that you could, you know, change some sliders to sort of change the detuning or turn beams on and off, then, you know, you could give that simulation to people and they’d be able to sort of play around with it and find out what what’s going on and sort of look under the hood a little bit. So that’s a bit of the dream there, is that we can use this research quality code also for doing outreach because we can cross compile it against the sort of video game rendering libraries that are out there and then, you know, basically compile it for web assembly and, and put it up. So yeah.

🟢 Steven Thomson (36:13): So physicists and other research scientists have something that they can learn from video game developers. And in terms of how do you…how do you write good, fast code that can be tested well, and that as a bonus also allows you to have some kind of intuitive view into the physical system that you’ve simulated.

🟣 Elliot Bentine (36:31): I think so, but I think, I mean, to be honest and without being too rude to physicists, I think a lot of physicists could learn a lot about code full stop. You know, I think academia is famously bad when it comes to keeping up with modern programming practices. I’m very pleased to see that, that things like Git and version control are now more widely used in academia. But you know, I mean, even until recently, you know, I know of research groups who still just take each version of the code and put it in a new folder, labeled version one, underscore new or something like that. And obviously that leads to errors and ultimately will lead to incorrect conclusions that then go on and get, you know, sort of appear in papers. So I think when you compare that to the whole software industry, that’s had to figure out ways of solving these problems and also to work collaborative as well. You know, they’ve got very good collaborative tools that are quite well suited to, to doing programming in any team, not just theirs, but also in the kind of teams you have in research that it seems a shame not to use those tools.

🟢 Steven Thomson (37:40): It’s a good point. I mean, there’s a serious point in there about reproducibility of your code and your numerics, because if you can’t reproduce the conclusions of an earlier study, then that’s a really big problem. And you’re right. That being able to use these sorts of these sorts of best practices, I guess, from an industry that really requires them…if we can borrow these best practices and use them also in research, then that does really benefit us as well. Have you seen much interest in the wider community in adopting these tools or have groups that have longstanding codes, have they been quite content to keep their closed code and work with that? Or have they showed some interest in becoming a part of this project?

🟣 Elliot Bentine (38:24): So I think we now have had kind of pull requests accepted from quite a few different groups. Now, I think there’s…it is quite hard to estimate how many different groups have used it because often people on GitHub will use a handle that, that, you know, doesn’t necessarily correspond to their real name. So it can be quite hard to track and work out, you know, who different contributors are actually, like, which groups they’re coming from. But we know, I mean, I know of at least five or six different groups now who have used it for simulating different things. We’d still like to improve it a bit more and make it so that it’s really, really user friendly, you know, so that people can quickly take it and use it in their projects.

🟢 Steven Thomson (39:05): Okay, great. So there’s one question that I like to ask all guests on this podcast and that’s to do with the gender balance in this field. So you’ve talked a bit about your experience, both in physics and also in programming and more kind of computer science based fields. These are both fields that in the, in recent history, let’s say, have been very, very male dominated. Is this something that you’ve seen changing over the years of your career? Have you seen these fields become more equal or noticed any appetite, any kind of momentum towards making these fields more equal, any kind of positive changes in these fields?

🟣 Elliot Bentine (39:42): There’s obviously a lot of issues that are still very entrenched in physics quite often. I see, you know, all male panels at conferences, for instance…it’s a terrible balance in physics. And, you know, I think that there was a recent analysis maybe two years ago that said that physics is actually going…is actually sort of one of the only STEM subjects that’s going backwards and where the divide is actually getting worse.

🟢 Steven Thomson (40:07): Oh really? I hadn’t heard about this.

🟣 Elliot Bentine (40:08): That is kind of possibly…I hope that’s outdated now. I don’t really know how, how to fix it. I mean, my own personal view is that I’ve sort of largely given up on, on academia just as a…as an entire culture, basically. I mean, that, that’s somewhat, you know, my reasons for basically leaving physics in the near future. Like, it’s very reluctant to change. I don’t have the answers of how to fix it. And personally, I’m really tired of it and I just sort of feel, I just can’t really carry on working in it so, yeah, I’ve sort of taken the decision to leave academia basically and, and trying and do research a different way. That’s not what I was thinking of doing a few years ago, but I don’t really…I know I feel at some point if I stay, I’m just sort of enabling the culture, you know? The culture exists as long as there are people around to sustain it.

And I dunno, gender imbalance is obviously one important thing. It is just very white male dominated at the moment. You know, there’s all kinds of groups who are very poorly represented in physics. And I don’t know how to fix that or change that. So some people will claim for instance, that that’s down to, you know…effectively access needs to be made sort of earlier on in people’s careers to get them into physics. But also, I’ve seen enough of people having horrible times within academia and within physics to feel a little bit of like, well, you know, if it is broken and it’s not gonna give people opportunities, even once they’re actually in it, then am I actually doing something of a disservice encouraging people to just throw themselves into a, into this like completely broken system?

🟢 Steven Thomson (42:01): That’s an interesting point, I guess, rather than trying to fix the system from within, your preferred approach then is just abandon that system and create a new and better one in the first place that doesn’t have these entrenched…sort of years and years of biases and problems that are built up over a very long period of time.

🟣 Elliot Bentine (42:21): I would like to create a system like that. As in, I would like to create a new place where you could do research that wouldn’t have the sort of problems of academia. I wonder to what extent the private sector - and kind of industries that are basically very physics heavy in the private sector - have they found out ways and solutions for fixing this problem? I know some of them haven’t because some of those companies are also still very white male dominated. But I hope somewhere there are companies that have, yeah…

🟢 Steven Thomson (42:53): Well, if there are, then I hope the rest of industry and research can learn from them and adopt some of their practices and make physics a bit more welcoming to people from all backgrounds, really from all walks of society and yeah, make things a bit more equal and a bit more diverse. As a final question to end on, then: if you could go back in time and give yourself one piece of advice, what would it be?

🟣 Elliot Bentine (43:23): I think probably the most important thing that I’ve always tried to encourage other people to do during the PhD is to basically…I try and encourage people to just learn as many different skills as possible to kind of work on, on the level of personal development. Like on the one hand, it, it should be because you enjoy doing those things. Like follow…you know, follow your interests and, and kind of work on the things which you are enthusiastic about. But I think it’s sort of…get out of your comfort zone a bit and, and, you know, try and learn as many different things as you can. Because you don’t really know necessarily when things are gonna be useful. And, you know, the sort of slightly eclectic bunch of skills that I’ve picked up over the various years ranging from things like the graphics programming, which has become useful in, in physics and also kind of, you know, game programming, which has now also become useful in physics as well, you know, to all these other kind of things…like, so for instance, with the physics, you know, in doing cold atoms, you learn - and experimental cold atoms - you learn a lot about different computer aided design things or like how to manufacture things or you learn about optics and lasers. And at the time, you’re kind of learning them because you need to learn them for your experiment, but you know, those are actually very, very useful and valuable skills in and of themselves. So one of the projects that I’m, I’m now working on with a postdoc from cardiovascular medicine called Dr. Winok Lapidaire is a sort of imaging device for cardiovascular medicine. And that’s obviously is completely different to the, the quantum physics that I’m more usually used to. But really, you know, what it draws on is that whole experience of working with lasers and optics and designing those types of systems for imaging cold atoms. But now instead I’m trying to image for instance, small blood vessels you know, instead for medical care rather than for doing physics. So yeah, I guess if I was gonna, if I was gonna say some advice, I would just say learn as many things as you can, and learn them because you’re interested in them and just kind of follow your passions that way.

🟢 Steven Thomson (45:39): Okay. Learn as much as you can. You never know when it could be useful or what kinds of unanticipated opportunities could come your way because of it.

🟣 Elliot Bentine (45:47): Yeah. Okay.

🟢 Steven Thomson (45:48): I think that’s a great place to end. So, if our audience wants to learn a bit more about you or check out some of these simulations that you’ve mentioned, where can they find you on the internet?

🟣 Elliot Bentine (45:59): So on Twitter, I’m Dr. Bentine. So D R B E N T I N E.

🟢 Steven Thomson (46:06): Okay, great. We’ll make sure to leave a link to your Twitter profile and possibly I think also your GitHub repository and various other links so our audience can always check out some of the things that you’ve talked about here today. Okay, great. Well, thank you very much, Dr. Elliot Bentine for your time today.

🟣 Elliot Bentine (46:24): Thanks very much for having me.

🟢 Steven Thomson (46:25): Thanks also to the Unitary Fund for supporting this podcast. If you’ve enjoyed today’s episode, please consider liking, sharing and subscribing wherever you like to listen to your podcasts. It really helps us to get our guest’s stories out to as wide an audience as possible. I hope you’ll join us again for our next episode, and until then, this has been insideQuantum, I’ve been Dr. Steven Thomson and thank you very much for listening. Goodbye.