From Earth orbit to the Moon and Mars, explore the world of human spaceflight with NASA each week on the official podcast of the Johnson Space Center in Houston, Texas. Listen to in-depth conversations with the astronauts, scientists and engineers who make it possible.
On Episode 257, Dr. Nathan Lundblad and Dr. Jason Williams discuss the importance of the Cold Atom Laboratory on the International Space Station, where NASA’s Biological & Physical Sciences Division out of NASA’s Jet Propulsion Laboratory remotely conducts quantum science. This episode was recorded on July 28, 2022.
Transcript
Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 257, “The Coolest Experiment in the Universe.” I’m Gary Jordan and I’ll be your host today. On this podcast we bring in the experts, scientists, engineers, and astronauts, all to let you know what’s going on in the world of human spaceflight. A huge impact at the smallest scale: when you hear “quantum science,” what’s the first thing that pops to your head? Would it be the coldest spot in the entire universe? Would you think that it’s just 250 miles away from Earth? Maybe you’re thinking about a different state of matter or quantum bubbles? What could only be imagined by science fiction writers is now possible with a facility called the Cold Atom Laboratory, or CAL. CAL is a facility on the International Space Station that allows researchers to dive into amazing atomic and quantum discoveries, which could only be possible due to the space’s microgravity environment. The lab launched in May of 2018 and over the past couple of years has already shown revolutionary breakthroughs for quantum research. Joining us today to discuss CAL we have two of the best in the field. Dr. Jason Williams is joining us from NASA’s Jet Propulsion Laboratory in Pasadena, California. Jason specializes in developing light pulse atom interferometers and optical atomic clocks, and how to use them in space. He currently serves as the project scientist and as a principal investigator studying space-based atom interferometry on the Cold Atom Lab or CAL project. During his time at JPL he’s been awarded both the Lew Allen Award for Excellence and the NASA Honor Award Early Career Public Achievement Medal for early-career contributions to the field. Jason received his Ph.D. from Pennsylvania State University in 2010, studying ultracold Fermi gases, and held an NRC Postdoctoral Research Appointment at JILA and the University of Colorado, developing high precision optical lattice clocks before joining the Quantum Sciences and Technologies group at JPL in 2013. We also have Dr. Nathan Lundblad, who is a professor of physics at Bates College in Lewiston, Maine. Before he did a Ph.D. in ultracold atomic physics at Caltech, working in a lab at JPL, and a postdoc at NIST (National Institute of Standards and Technology) Maryland applying cold atom techniques to potential quantum computing architectures. Majoring in astrophysics at Berkeley as an undergrad, thinking he wanted to be a radio astronomer beforehand, he changed his mind once he got to play with lasers and was pulled into the atomic physics side of things. At Bates he maintains a low-temperature physics lab where he works mostly with undergraduate researchers and also maintains a collaboration with NASA JPL to use the Cold Atom Lab facility aboard the International Space Station. Both Jason and Nathan will be shedding light on the Cold Atom Laboratory on this episode. They’ll be talking about what it is and the impact it’s having on us in the present, as well as what it will have in the future. With that, let’s discuss the coolest experiment in the universe — literally. Enjoy.
[Music]
Host: Jason and Nathan, thank you so much for coming on Houston We Have a Podcast today.
Jason Williams: All right. Thanks very much. Glad to be here.
Nathan Lundblad: Thank you so much. Glad to be here too.
Host: All right. The coolest experiment in the universe, that’s what we are talking about today. And of course, the idea here is, is we’re getting into some, some quantum mechanics, quantum physics, and I’m absolutely going to be leaning on you to help me and our listeners and guide us through just what is this and why this is important to the International Space Station. But to me, you know, of all the things that you could pursue, this one, it’s very intriguing but to me, it just seems so difficult. So I wanted to first start with, you know, who it is, who it is that we’re talking to and, and why it is that you pursued this quantum physics and what’s so interesting about it. Jason, I want to start with you. Can you talk about what led you to talk your, your education and, and your passion for this kind of research, what led you to pursuing this particular field and ending up working on CAL?
Jason Williams: Sure. Yeah, so going all the way back, I grew up in a relatively small town in Idaho. My father was actually a chemist and my mother was a teacher so I had a pretty healthy education in science and math growing up, but my love for physics and fundamental physics, including quantum mechanics, didn’t really blossom until my first few years in college. So, that time I was studying psychology. My daughter, who’s first of my four children, was under a year old, and I had a lot going on but I still found myself reading articles on physics for fun. There’s a lot going on at the time: Hubble was repaired and had been returning some great images, exoplanets had just been discovered, and there were some rumblings in this field of ultracold atomic gases that the new face of matter might be discovered or might not, might be impossible. And so I decided to switch to physics because it was just so interesting and so promising at the time. Worked in high energy physics in undergraduate at Idaho State University, and then after that went to grad school and there’s where I knew that I wanted to study ultracold gases. And so I worked with Ken O’Hara at Pennsylvania State University, studied some ultracold fermions making some really cold molecules, and then went to work with Jun Ye’s group in JILA, making one of the most accurate and precise clocks at the time using an optical transition in strontium, and all that really came together for me to want to work with NASA, to look in fundamental physics and specifically use quantum mechanics and ultracold gases to do that.
Host: Wonderful. Wonderful. Yeah, very interesting stuff. Great to have a fellow Penn Stater on. So this is going to be a very, very interesting conversation, I think. Nathan a, a little bit about your background as well. You, you, what, what exactly led you to this, seems like these, ultracold atomic physics seems to be, that passion seems to be shared with you and Jason, talk about what led you down that path?
Nathan Lundblad: Sure. Well, there’s some similarity there where my mom was a teacher growing up and I had a curiosity about science growing up as well. I had an uncle who gave me a copy of this book called “A Brief History of Time” by Stephen Hawking, which was a big popular science book in the 80s and 90s. And I didn’t understand much of it, but it kind of set off a, a little spark in my head that, like, there were some secrets here that needed to be uncovered and figured out. And so I went out to college thinking I would major in physics and maybe do astronomy or be a radio astronomer, like the Jodie Foster character in that movie “Contact” that came out when I was in college. But along the way, when I was in college, I worked in a lab that had some lasers and tabletop experiments with lasers, and I really got excited and motivated to build my own experiments and then be able to do experiments in a lab; honestly, playing with lasers is, it was kind of a, a mad scientist vibe as a, as a college student being what, or being allowed to play with these things. And it turns out the lab I was in was doing atomic physics, studying the properties of cold atomic samples. And so when I, when I went off to graduate school to study more physics I ended up getting routed into looking at the physics of what happens when you get really, really cold, and I got more and more into this as a, a Ph.D. student and then as a graduate student I studied how to use these cold samples, ultracold samples, to maybe build the bones of what’s called the quantum computer, which is getting a little more traction these days. And since my time at the national lab I’ve been at Bates College in Lewison, Maine, doing ultracold atomic physics there and with my students, and also collaborating NASA on this project.
Host: Very interesting. So, so let’s, let’s pull back for the both of you. There’s something, there’s something that was intriguing you both on, not only atomic physics but then this idea of what happens when you, when you cool atoms a significantly, a significant amount. And then there’s this idea of quantum. Nathan, I’ll, I’ll, I’ll pass to you to just sort of give our listeners just a high level, what’s happening here? What, what is, what is happening with the atoms when you cool them down? And then what truly is quantum mechanics?
Nathan Lundblad: The way I like to think about, about this is that the way we learn about atoms, maybe the first time and maybe the way I sort of even think about atoms most of the time, is that there are these little point particles zipping around the room, bouncing off of each other, and they’re like little billiard balls. And that’s how we usually think about what matter is, is like little, very, very small versions of balls or chunks of stuff that we encounter in our daily life. But the weird part about physics is that when you get them colder and colder and colder, they start behaving in really different ways and they start behaving like waves. And we’ve all encountered waves, you know, at the beach or, you know, sound waves, so we know that matter can behave like a wave like that. But you know, at the end of the day with a water wave it’s still water molecules bouncing around, touching each other, kicking around in the ocean or something like that. When we cool these gas samples down further and further and further, they actually behave in ways that are pretty crazy. They can actually pass through each other, tunnel through each other, interfere with each other in ways that are, is just totally counterintuitive to, you know, us big humans. Like if I run at you, you know, I run at a wall, I don’t tunnel through it, I don’t interfere with the wall or anything crazy like that. So what we’re doing in these experiments and trying to uncover is how can we make these things behave like waves in ways that are actually more visible to the naked eye, and a trick to do that is to get things cold. So ultimately when I think about quantum I think about waves, and I think about interference and I think about, sort of, matter behaving in ways that is counterintuitive to our daily experience.
Host: OK, I understand; you have this understanding of what’s happening at the atomic level and what, what defines, what defines the universe and what we understand about it. But this, this idea of quantum is just, it, it defies what we perceive as how the universe works. Is that, am I interpreting that right?
Jason Williams: You know, that, that’s right, but at the end of the day if you’ve taken some, you know, chemistry or something and you learn about how atoms behave, they’re all governed by these laws of quantum mechanics. It just that a lot of it is shielded from our daily experience because when [you’re] walking around the neighborhood you don’t actually interact in a way that feels quantum mechanical, but when you actually try to explain how atoms work and how stuff works at a microscopic level, these, it turns out these are the rules that actually apply.
Host: Very interesting. So, so Jason to, to help us lead into talking about the Cold Atom Lab, I want to talk about your, your research and, and what you understand about facilities and, and what, what it takes to design a facility to help us to look at this, right? It’s, it’s all about, it’s all about cooling things down, but I think what’s surprising and to me very, very difficult to comprehend is just how cold we’re talking. There’s this idea about absolute zero, but we’re not quite there, we’re getting, we’re getting close to there. So, so can you help us to understand, you know, this process of cooling down to, to this, this concept of, of absolute zero and, and how facilities on Earth do that?
Jason Williams: Yeah. And I think there are a couple of different, interesting aspects to the question that you ask. As, as Nathan had mentioned previously, when he went to work in an atomic physics lab for the first time, it was a interesting and unique experience on Earth. These ultracold physics, or atomic physics labs are generally relatively large. There’s many, many optics that are spread over many tables, a small team of graduate students that are working often long hours late into the night to make sure everything is working well. And really a lot of cutting-edge technology comes into making atoms ultracold. And so, I mean, [to pro]duce these cold gases you, you actually start with hot gas. Often you are taking some atomic species — rubidium, potassium, lithium, you name it — and you’re heating it up. But there are many stages where, thereafter where scientists use laser light actually to cool atoms, which is one of the first non-intuitive things that I ran into in the lab also is that usually you use lasers to heat things up, or even to weld, for example, or cut. But here, the lasers can be so precise, and really so tuned into atomic transition that they are removing energy and they’re, they’re, just in that process alone you can slow atoms down from say, moving around at the speed of a jet like we have at, for room temperature gases, to causing to go as slow as, as say a child crawls or for humans walking around. And then other technologies that, that were developed in the, the 90s and actually led to Bose-Einstein condensation and, and a number of Nobel Prizes, included evaporative cooling where you are, this is similar to if you have a hot cup of coffee and you’re blowing across the top, removing the hottest particles to cool it down. It’s a, a very efficient method and scientists use that to cool atoms down from microkelvin temperatures to nanokelvin, or, or below. And, and so these ideas of what is a microkelvin, what is a nanokelvin, these are, these are really slow temperatures. I mean, there, there is a, an idea of an absolute zero temperature, as you mentioned, zero Kelvin, in which all of the atoms would be perfectly stopped. There would be no motion in, in a gas. Quantum mechanics says that’s actually extremely hard to get to if you have, if you have a, a, a gas or anything there’s certain uncertainty of relations: the better you know its position, the worse you will have the ability to detect its momentum, and vice versa. And so by cooling things, particles, down, etc. etc., we’re knowing its velocity distributions better. It’s, the position becomes more uncertain, and that’s where the wave-like property of atoms come in. And so these are all technologies that have spent a few decades and really rapidly grown on the lab and a number of labs around the world. Our challenge with Cold Atom Lab was to take these technologies, take this large room-worth of stuff, lab equipment, and compact it all into an apparatus that could, that could operate in a, a single rack on the International Space Station. And not only that, to transfer from the paradigm of single-user instrument like often occurs in academic labs to a instrument that is run autonomously, remotely, and can produce science for, for many, many different users who are selected specifically by NASA to do fundamental physics research. That’s of interest to NASA and the U.S. strategic interest in the future. So there were, was not only a, a development on the instrument side to take commercial components, miniaturize them, but also a maturation on automation of how these experiments work and, and a bit of a culture shift, too, to make it work out well for NASA. But yeah, it’s all worked out very, very well. And I, I mean, very large part of that comes not only from the teams at JPL and the support of our sponsors, but, but all of the PIs (principal investigators) have, have really enabled the research that we’re doing on CAL.
Host: We talk to a lot of PIs on this podcast and that is by, by and large of, of one of the most common themes is this idea of taking some technology and, and this complicated technology that takes a lot of energy, a lot of space on Earth, and then coming up with some fancy engineering way to, to make it work. And I do want to dive, I do want to dive into that a little, a little bit more, and just, you know, how, how CAL was miniaturized and, and compacted and, and how it works. To better understand, though, this, this concept and, and why we’re doing this though, Nathan, I want to go to you for a second because and, and continue to explore this, this idea of, of quantum mechanics and, and what’s happening when you cool these, these atoms. One of the things that Jason just mentioned was this, this Bose-Einstein condensate, and I find this very fascinating, this, because this is, it is, how it’s characterized is, is a fifth state of matter. Can you help us to understand what exactly that means in terms of physics and relations to other, and to other matter?
Nathan Lundblad:Sure. I usually like to think about Bose-Einstein condensation as imagining a bunch of atoms bouncing around in a box kind of like the molecules in the room you’re sitting in. And if we make them go slower and slower and slower, the laws of quantum mechanics actually blur out where they are, they behave more and more like waves. And eventually that kind of that blurriness or the uncertainty of where the atoms are becomes so big that it actually overlaps with the other atoms in the box. And at a critical temperature or critical speed, you can’t actually say that you’ve got one atom here, one atom there, one atom over there: they actually all are everywhere in that box at the same time. Sometimes people call it the formation of a super atom; I, I find that a little confusing, I don’t really know what that, that means. But I think of it as all the atoms are located everywhere: it’s like a collective state that’s formed where they’re all acting together, all acting in concert with each other, and they’re not located in any one spot. And when this happens, you have to get below a critical temperature, and a critical temperature is pretty similar to anyone who’s tried freezing water or boiling water, right, it’s a temperature where something really special happens to a substance. And with the gases that we use, when we cool them down below a critical temperature, they form this collective distributed state where all the atoms are everywhere in the trap, as opposed to one side of it or, you know, an atom here, an atom there. And that’s, this is how I think of what the phenomenon of BEC, or Bose-Einstein condensation. It’s called a fifth state of matter because even though it’s still a vapor and it’s still a gas, it’s behaving fundamentally differently than any kind of gas that you would encounter in daily life.
Host: OK. It’s about its behavior. Now in terms of that, right, to, to help us to, to eventually lead to this Cold Atom Lab, this idea of a Bose-Einstein condensate, can you talk about the research done on facilities on Earth to explore this fifth state of matter, and then — this is a two-part — the second, the second one that helps us lead into that is, what is intriguing about microgravity and exploring quantum physics there, and Bose-Einstein condensate in microgravity that became intriguing to you as a researcher?
Nathan Lundblad: Sure. So in the last, I think it’s almost 30 years now, Bose-Einstein condensation was first discovered, there’s been a really explosive growth in number of labs around the world studying it. There’s probably, I’m going to guess 1,500 labs around the world that can actually achieve this state of matter on any given day. The things that they’re studying at this point are actually using BEC or Bose-Einstein condensate as a starting tool to understand how quantum mechanics works on a macroscopic scale. It makes something in a lab that behaves very quantum mechanically, but can actually be observed with a, you know, not super-expensive camera and a super-expensive laser as opposed to having a single electron or observing a single atom or smashing atoms together. That actually gives you a window into quantum mechanics as a, a branch of physics and testing some of our ideas of how quantum mechanics really works and testing some of our ideas of how quantum mechanics plays out when you do it on a macroscopic scale and not just the, you know, single atom or single electron. So the, the BEC actually is a tool that allows us to, I guess, kind of amplify quantum mechanics or make quantum mechanics bigger, if that makes sense. The, the specific interest of microgravity actually comes out of what are the limits of what we can actually do in the labs on Earth. A lot of what people try to do with some of these BEC machines is change the shape of the condensate, change the shape of the box that it’s in, try to make Bose-Einstein condensate that are in the shape of a donut or in the shape of a disc or in the shape of a, a needle; playing around with a geometry and the topology and the sort of almost dimensionality, whether it’s like almost two dimensional or one dimensional, can actually change the physics of how these things work quite a bit. So along the way, I think probably around 2000, there was a theoretical idea to make a Bose-Einstein condensate in the shape of a bubble or a shell. So just like a soap bubble, it has a hollow center and all the atoms exist on the surface of a sphere, something like that. And this would allow you to test some of these laws of quantum mechanics and the wave, the wave nature of matter but in a really strange environment, it’s like on the curved surface of the Earth, the same way you would get kind of like Coriolis forces as you move air around the Earth or the fact that you move around the Earth you’re actually moving on a curved surface, even though you might think it’s flat when you’re sitting in your room. All these physics ideas can come to the fore when you’re trying to make a BEC that’s shaped like a bubble. Trouble is if you try to do it on Earth, it just doesn’t work. It just sags and pops because of the influence of gravity. And so the, slid to the idea of trying to do it in space.
Host: Very interesting. So, so Jason, I, I expect you were thinking sort of the same things, this idea of geometry and trying to get the Bose-Einstein condensates in a, in a certain way. What led you and your team to start thinking about, hey, what if we took this facility and put it into low-Earth orbit? Can you talk about the genesis of Cold Atom Lab?
Jason Williams: Yeah, I can certainly talk about that. But I, I wanted to mention that geometry is, is, is very enabling in, in space. That actually was not one of the first realizations of the use of cold atoms in space; that was, I’m going to say sort of the genius idea of Nathan to, to bring this. That the original ideas of why you go to, go to space have been thought about for, for decades now. And one, it, it was recognized fairly early that we, we can cool these atoms on Earth, but there are certain limitations. You always have to have, hold the atoms in a trap of some kind, generally by magnetic or optical fields, and the strength of that trap is defined by gravity on Earth. If you make the trap too weak or perturb it too much, then atoms can easily spill out and you’ll lose your atoms altogether. By going to space, you can actually achieve regimes where atoms can get colder. You remove that limiting force of gravity and thereby getting colder you now have the ability to explore new energy regimes for these atoms, to look at the under-nanokelvin, look at atoms at picokelvin or cooled to a ten-billionth of a degree above absolute zero, where the atoms are now moving as slow as a snail. And what that brings with it is that many of the, the emergence of, of interesting dynamics in physics is slowed down to levels where you can, can take pictures of them. And I should mention that that’s one of the things that I love about our discipline and Cold Atom Lab is that all of our data comes in terms of pictures that we’re taking of these clouds. So you not only get to see a data point, you get to see any structure dynamics in real time as the data comes down. But anyway, I digress. And then another, another interesting benefit of microgravity is that on Earth if you want to do some studies of two different types of atomic species — rubidium and potassium, for example, is used in, in CAL — as you cool them down they can begin to separate, called gravitational sag. And that does not occur in space. Certainly there is no relevant sag, and so you can look at interactions, look at how two species interact with each other, and you can actually even tune their interactions and make molecules out of them — again, at energy levels that are unachievable on Earth. And of course, you can observe them in free fall for very long times in space. So there, there are many benefits of going to space that, that are useful for studying fundamental physics and, and also for potentially using these atoms as, as precise sensors for gravity and, and accelerations, rotations, and even looking at their, their interactions with each other and looking at the emergence of, of structure in the gases. So, so that, many of these promises have been thought about for quite some time. At JPL and, and how CAL came about, it was the dream of JPL physicists for well over a decade, I’d say, before it was funded. And so some of the scientists, like Rob Thompson, who is the original project scientist and now is program scientist for ultracold atom research at JPL, Dave Aveline, who’s science module and ground test bed lead and is Co-I (co-investigator) on Nathan’s project, and in fact Nathan worked at JPL in the early days to mature some of these technologies for BECs for flight. But, and from that, and during the time there were regular fundamental physics workshops to gauge interest from the community, CALs really a first of its kind. But it wasn’t until about 2011 or 2012 when, when a call came out for doing this type of fundamental physics research on the ISS, and after a number of efforts CAL was accepted and officially formed into a project in 2013. And then of course the, the call for researchers, called a NASA Research Announcement came out in 2013, and, and from there, the, the instrument was built up, until it launched in 2018. And so that, that period from 2013 to 2018 was, was a busy period, as you can imagine. We actually, using CAL, were able to use custom off the shelf parts to go to vendors, to grab some of their cutting-edge technologies and lasers and radio frequency drivers. And also, vendors like ColdQuanta, who are producing for the first time very small vacuum systems that we can produce our atoms in and very small ways to make compacted vacuum systems to produce Bose-Einstein condensates reproducibly and fast. A lot of this technology was really cutting edge. So there was an effort and, and I should say a number of lessons learned in what, what it takes to grab something off the shelf but actually mature it and make sure it will survive launch, will not impede other instruments or not give off electromagnetic fields that could be perturbing to other instruments, and be rigorous enough to have very high confidence that these, these devices will last for three years just running autonomously on the ISS because although we do have, one of the great things we have for CAL is that being on the ISS we have the ability to pull in astronauts if repairs or upgrades are needed, and we have done that a number of times, that’s worked out really great — we try to minimize that. The CAL generally is a system that’s designed to work without regular astronaut interface. And so, so yes, the, this mini, miniaturization effort was also a technology maturation effort to try to make it more robust. And a lot of the, the technologies like lasers, the lasers that we’re using had not been flown before. And so it, it was a, it was an interesting but now a, enabling effort. We had now, have a very nice baseline of the technologies that, that, that are ready for a number of other spinoff missions or relevant missions like CAL. But yes, we launched in 2018 and CAL has been making Bose-Einstein condensates almost on a daily basis; ever since that time it’s been going really well. We’ve gotten, we’ve run tens of thousands of experimental runs for PIs and gotten a, a lot of really great results out of CAL in that time.
Host: That’s got to feel good, but I, I, I bet particularly after that at, that challenging time that you were talking about the, the construction of Cold Atom Lab and really pushing the limits of, of design and engineering…
Jason Williams: Oh yeah.
Host:…it had to feel really good to see that thing launch to the International Space Station. Did you get to actually go out and see it?
Jason Williams: It was really great. I did not get to go out to that launch. But, Nathan, did you get to go to that lunch and see it go?
Nathan Lundblad: Yeah, I was, this is very, very, very early in the morning out of Wallops [Flight Facility], and I had never seen a live rocket launch before, and it was absolutely mind-blowing. But imagining something like I had built in my lab going onto a rocket, which is essentially, you know, this explosion pointing out one end of a rocket, it’s, it’s terrifying for anyone who’s actually had to deal with real hardware. And it means the, the level of respect for the JPL people who have actually figured out how to make these delicate machines withstand the violence of launch; it’s absolutely astounding.
Jason Williams: Yeah.
Host: Yeah, because Nathan, you were, you were involved in like the, you were involved in some of the early designs for Cold Atom Lab, right? And I’m sure, not only were you thinking about the hardware, but you were also thinking about the potential research, everybody who you knew was going to contribute, you were like, man, this thing’s, I hope, I really hope this thing works, right?
Nathan Lundblad: That’s right. And you know, as a potential user, when we were consulted about what we wanted for the machine or kind of a wishlist for capabilities, we could throw ideas out there and you could just see a couple of the engineers in the rooms just cringe as they like, think like, how are we possibly going to do that? And in general they, they made it work. There’s some, the lasers are better than I would’ve expected for, you know, if I took anything in my lab in Maine and started shaking it the way any of these, these things got shaken a launch, they would stop working immediately. So it’s, this is fantastic to see it actually work, actually, see these images come down from communication from the ISS.
Host: Yeah, let’s explore that a little bit. Oh, go ahead, Jason. Sorry. I, before I go, my next question,
Jason Williams: I was going to say, I did get the chance to see a launch of a spare science module that we put up, which is the, the heart of the, the instrument, includes the vacuum system, on a, a later launch in 2020. And it is a exciting experience, but there is a long period where you’re holding your breath, as Nathan had mentioned, while you’re watching this rocket. And they’re, they’re — seeing one in real life, that was also my first – they’re, it’s a striking experience. They’re very loud and very dramatic.
Host: I’m always interested to hear about, for the, the, the researchers and investigate and investigators, because I feel, I feel like it’s, it’s just a different experience from, from the typical, you know, like for, for just someone in the public watching a rocket launch it’s, it’s a, it’s a fascinating experience: you feel it, you, you can see it, it’s just a, it’s, it’s just a marvelous site, I’ve gotten to see a couple of launches myself. But I think the, the [e]motion behind knowing that something that you poured so much energy and time and effort into is on that rocket, I just feel, I that’s, that’s something that I always find extreme, very fascinating to, to researchers.
Jason Williams: Yeah, absolutely.
Host: Did you guys have those emotions, right? Those, yeah because just, you know, I, it seems like the first rocket launch that you got to see was something that is, it’s, it goes beyond just your typical viewing. It’s something that you’re, you have an emotional tie to.
Jason Williams: Yeah, absolutely. And, and you summed it up very well. We…
Nathan Lundblad: That’s right.
Jason Williams: And we, we have, we’ve worked very close with these apparatuses for, for many, many years, and we also have a pretty good sense of, of what type of environment it’s been in — clean room environment — for the last [few years], and have, I think each of us have some experiences maybe during our grad school years where there was a, one small issue that delayed our, our research for six months or more, so it’s, it’s, it’s actually for a couple of days until it’s, everything was installed and working properly, it was a lot of emotions for, for me, at least.
Host: I, it’s, it’s never really a smooth ride, right? Wouldn’t it be nice if it was, but especially on something that’s so novel and it’s a, it’s a first, you know, you’re always going to have those bumps. But, as you mentioned, like you said, you got it installed through, through some of those emotions, through some of the difficulties, the obstacles and, and, and you got it up and working. Jason, tell us about the operations of CAL. You, you mentioned making Bose-Einstein condensates on a daily basis. I mean, you’re, you’re running this thing seems like all the time, so what’s it like from the operations perspective of, of, you know, continuing to, to create these, this fifth state of matter?
Jason Williams: Yeah. So we, we produce Bose-Einstein condensates on a daily basis. In fact it’s, it’s one of our first steps in, after we start up each day, to calibrate the instrument and make sure that it’s all running well. So the instruments on the ISS, we, we actually command it remotely from the ground. And in the early days this was all operated by operators and the missions operations team from JPL, a command center in the JPL. During the pandemic we actually very quickly switched over so that the entire team could run the instrument remotely from our own homes or wherever we needed to in order to get the instrument going. And so this is not 24/7 operation. The instrument we, we can start up each day which includes turning on lasers, warming things up and heating up our atom sources, etc. etc. But the, the operators are provided a set of so-called tables, and basically what this is is it’s a time-ordered list that tells, that runs through a sequence of what, what your magnetic fields should be at for a given stage, what your laser of frequencies should, should go to to cool the atoms just right, and, and what you need to evaporatively cool the atoms, for example. Those, those tables are developed with the principal investigators and each table is unique, each table has a different goal in order to poke and probe the atoms or prepare them in a specific way to get just the, the right science that the PIs need out. So we run generally one, one table, probe the atoms one time every minute, and then that’s a destructive process. The, once we take pictures of the atoms they’re destroyed, and it starts over again, but the instrument is repeatable enough that you can just take the same, same picture over and over again and, and essentially get almost exactly the same results every time. And so we do, those are the operations that we do every day. Even now we often operate remotely, even from JPL, because we have a system where the operators and myself and the science team can see the data coming down in real time and we can tweak and, and probe, change as needed, so there’s, there’s actually minimized amount of time that we’re down or that a table doesn’t work out correctly. We, we have really fast feedback. It’s been really great experience. That actually was not obvious that we’d be able to run in such a smooth way with the potential delays to communicating to the ISS, there were concerns that, that we might have to, we might not be able to operate in such real time, but it, it has worked out really great.
Host: That’s really good to hear, and that’s a lot of science over a lot of time. So let’s, let’s, let’s explore exactly some of that research and, and what we’ve learned, what we’re doing. Nathan, we’ll start with you and your research. Tell us about, you, you mentioned, you know, not only helping with the facility itself but being a user; what was it exactly that you wanted to use CAL for? What was your research?
Nathan Lundblad: So probably, since I was a graduate student, I had known about some proposals from the, the theoretical physics community about what it would be like to make a Bose-Einstein condensate that was in the shape of a bubble. And at some point I had filed away this idea in my brain that was like, yeah, that’s neat but you’re never going to be able to do it because of the influence of gravity on Earth. And when NASA came out with this call for proposals, for potential users of a free-fall science machine, putting Bose-Einstein condensates in orbit, I immediately thought, hey, this is one kind of killer app that I could think of. So we wrote this proposal saying, hey, this is going to be one neat idea that is only possible if you could get into a, a lab that’s in perpetual free fall like the ISS. So over the course of the first few years of the project, where before CAL had gotten launched and even into launch it was basically my students and I, and some others, developing a lot of computer models of what it would actually be like to try to do this. So that involved modeling the, the magnets on the ISS, how the traps work on the Cold Atom Lab machine, and how this bubble creation process could actually work. Because it had been attempted on Earth and didn’t work for the reasons I said before — gravity just pops these bubbles. So we spent a few years essentially building up a model on our computers of how it would work. And then once CAL launched and was proven that it was a working machine, we started getting data weeks where it would be like, maybe, we would do bubble physics or these bubble inflation attempts for about a week and then analyze the data, and then maybe three or four weeks later get another week on, on the machine. Essentially, doing it back and forth between my college and, or my group at Bates in Maine, and with the folks at JPL where we would send them new ideas to try, new tables to run, and they would come back to us and show some things that they were seeing from the machine. And we would iterate from there. And given the time delay the way it would actually work most days is that I would have a conference call with a guy named Dave Aveline at JPL in the morning, you know, when he got to work, so it would be about noon my time; we would develop some tables, he would run them and then around nine or ten, my time, so end of the day on the West Coast, some of the screenshots of the data would start rolling in. So I would be putting my kids to bed or giving a kid a bath at my house, and I would get a text message from Dave sharing a screenshot of some of the things he was seeing. And I remember the, the first inflated bubbles we saw came when I was actually just settling down for the night after putting my kids to bed, and just feeling so excited this is actually working and couldn’t wait to try it again the next day.
Host: That’s amazing. So what, you, you know, you talked about the geometry and, and playing with it and, and getting them into these shapes, but for, from a research perspective, why, why do that? Why, why is it important? Why was it scientifically interesting to research these atoms, these super-cold atoms in this bubble formation?
Nathan Lundblad: So the main interest of doing this kind of thing really comes from the fact that atoms that are confined to the surface of the sphere behave a little differently than the ones that are just in a regular box or container. And one way to think about this is just moving around on the surface of the Earth: if you start from different points on the Equator and you move north initially, eventually you’re going to reach the North Pole and it means that parallel lines, the lines of longitude, actually bend and come together at some point. And it means that initially parallel flows of like air or water, if you go long enough, it will eventually converge and not be parallel the way we normally think about them. So that physics that we’re exploring there is what actually happens when you have these quantum mechanical flows of matter that are forced to be in a curved space or a curved geometry. And this could involve the vortices or the whirlpools of this quantum fluid behaving differently, it could involve the, what we call collective modes or what happens when you shake it — imagining shaking a, like a bowl of Jell-O and seeing the little vibrations that occur — and that fundamentally is going to be different in a curved space or a curved surface than it is in a flat surface. That’s what we’re looking for with these bubbles. The last thing we’re also looking for is kind of a curiosity-driven effect of it, seeing how big we can make these, how big we can make these quantum mechanical objects and have them still behave in a way that is described by these rules of quantum mechanics. And when you do this, the fact that you can get these up to about a millimeter scale, means that we are making some of the most delicate objects, I think, you know, in all of science: there are hundreds of thousands of atoms but spread out over the surface of a millimeter-size bubble, incredibly delicate, maybe about a millionth of a meter, sort of a percent of the hair thick around there, so almost kind of gossamer bubbles of atoms once you’ve inflated them to this, this size. And we don’t really, there’s some disagreement in the theoretical physics community as to how these actually work or the behavior of them once you get them up to the, roughly the millimeter scale, and we’re trying to resolve some of that tension.
Host: But really is it that size, as you mentioned before, it’s, it’s really about observation, once you, you know, cooling them down let’s, because lets you actually make observations and, and better understand quantum. Is that, is that the idea, increasing the size maybe?
Nathan Lundblad: Yeah, that’s right.
Host: And that’s the, and that’s the agreements you’re working through. OK. OK. Very good.
Nathan Lundblad: There’s, there’s some interesting links to the physics of turbulence and the physics of fluids and trying to understand how fluids work when they’re confined to these bubble shapes. And these are ideas or collaborations that have emerged since this proposal, they weren’t necessarily there at the beginning when we were proposing this idea but as we’ve given conference talks and talked to people around the, the world about this, we’ve gotten people reaching out to us saying, hey, like if you can actually make these, here’s some ideas of ways you could explore the physics of quantum turbulence or the physics of little whirlpools or vortices in these samples. And it’s really broadened our, our vision for what we can do.
Host: Is that one of the things I noticed about what’s, what’s interesting about these ultracold atomic physics, was these ideas of superfluidity and superconductivity? Are, is that sort of what you’re referring to or are these different concepts?
Nathan Lundblad: No, for sure. And superconductivity is this idea that below a critical temperature electrons can flow without electrical resistance; superfluidity is a very similar idea that below a critical temperature you can have liquids or gases that can flow without viscosity. Think of, you know, the, honey being a very high viscosity liquid, or motor oil being a very low viscosity liquid. Below some critical temperature you can have flows that have no viscosity. And if you can make one of these Bose-Einstein condensates they, they do exhibit superfluidity. And trying to figure out how superfluidity works when it’s confined to the surface of a sphere is pretty neat because one kind of, one fundamental property of being stuck on a sphere is if you walk all the way around it you come back to where you started. And that’s really not the norm for just a gases in a box, as you sort of leave it eventually you just leave the room, right, you don’t come, if I walk east out of the room I’m in I don’t end up coming in the west side door, but if you’re confined to a, a bubble or a surface of the sphere, you do. So these ideas of motion around a sphere and how that plays out quantum mechanically really drives what we’re trying to do.
Host: Yeah. I think there’s some engineering applications to this, right? Is that, I guess, is this idea of superconductivity, is that really the root of, of quantum computing?
Nathan Lundblad: Superconductivity has been this puzzle for, you know, maybe the better part of the century in that we can make these substances superconduct, and we don’t really know why it works. There’s a lot of competing theories and there’s some theories that are showing some signs of being accurate, but we really don’t have a, you know, lockdown, solid, you know, tell it to your kids, because its, its understanded, this type understanding of how superconductivity works. So a lot of the cold atom research over the last 20 years, people have been trying to find ways to attack that problem and try to look at superconductivity, which is usually done in solids, so chunks of stuff, to try to look at it from the angle of these ultracold gases and try to shed some light on it from another angle.
Host: OK. So, so definitely more research needed. OK. Very, I understand. And, and of course, Nathan you’re, you’re one user and, Jason, you sort of, you sort of alluded to the fact that, you know, to, to open up the Cold Atom Laboratory for, for more research and even, you know, beyond these bubbles, one of the, one of the interesting things is to, about putting the, a Cold Atom Lab in space is the idea to make it quite literally the, the coldest place in the universe, getting so close to absolute zero, I think closer than any ground-based facility. So, you know, that getting, getting super-cold and, and then some of the other research that you’ve seen for some researchers using this facility, can you give us a range of activities that have been happening in Cold Atom Lab since, since it was brought up the station?
Jason Williams: Sure. Yeah. So this quest for ultracold is actually one of the, one of the interesting and large goals for a couple of our principal investigators. The, the fact that we are in now in microgravity, there’s an ability to manipulate atoms and try to get them colder, is in itself an interesting question. And so there’s two PI teams: Nick Bigelow leads a consortium, he’s from University of Rochester, and Cass Sackett from University of Virginia, are both working on so-called quantum control. And this is the way, method of using the unique properties of these Bose-Einstein condensates to actually control and manipulate them to get them into the right state at the right temperature, to form them into the right shape, and really control these gases at unprecedented precision. And what, now that we go to space they’re, they’re a number of new cooling schemes that, that open up that are not as useful in, on the Earth to get very low temperatures. And so the, Nick Bigelow’s team in particular has gotten atoms down to about 52 picokelvin with expanse, expansion energies. And that is extreme[ly] cold, that is, I guess I would say that is the coldest region in outer space. And there’s, there’s one other group that is comparable that uses a very large drop tower to achieve microgravity on the Earth that has that, that is in Germany that has achieved 36. And so there, this, the work that’s going on in CAL has started, but that is, their efforts to, to go further and further in, in next generation. We’re, we’re really in the near future looking to try to get to picokelvin temperature regimes. And with that, your atoms are effectively stopped, are going extremely slow, studied now in the free fall of ISS for long amount of time. So going about, beyond the quantum control studies, we have a unique tool that was, as I mentioned, launched to the ISS in 2020 called an atom interferometer. And this uses the wave-like nature of atoms in a very blatant, very observable way. The idea in there is that if proper light is shined onto an atom it can actually split a single atom into two states so that, so that this single atom can separate along two different velocities. And with proper laser pulses you recombine the atoms and it interferes with itself, the wave function of the atoms interferes with themselves. And you get very similar sort of interference patterns as you would with light, like Nathan was discussing previously. Optical interferometers have been around for a long time where you do the same with lasers, and that’s the technology that’s at the basis of, of LIGO (Laser Interferometer Gravitational-Wave Observatory) to detect gravitational waves; can be an ultra-precise sensor. Here we are using atomically wave forms to, to also be highly sensitive in the near future to gravity. And so this is a technology that’s being matured by Nick Bigelow, Cass Sackett, and myself in order to use atom interferometry to be very sensitive to gravity, and now we have two species, rubidium and potassium, on the ISS and, we’re using this to try to mature the technology for eventually looking at possible different fuel signals, does rubidium and potassium, are they affected differently by gravity? Einstein’s general relativity says that they should not. Any possible deviations of that would actually signify new physics, and that’s one thing that we’re looking for is any new physics signatures, or we’re maturing the technology towards being able to look for deviations of, of these signatures for two quantum gases that, that could potentially give some insight into why quantum mechanics and general relativity for example, are not, not fully consistent models with each other. And then finally, having gases in space that can interact with each other, there’s a group [led] by Nobel laureate Eric Cornell and, and Peter Engels that are study, studying the quantum three-body problem where gases of potassium have this unique feature where their, the interactions among particles could be tuned with a simple magnetic field. What we mean is that you can make these particles attract each other or repel each other, make them so they’re almost infinitely interacting or there’s no interactions at all, just by applying a magnetic field. That’s really great. And with that, you can, we can form them into molecules or back in a very controlled way, and these molecules are very weakly bound. So-called halo molecules are much larger than anything you could form on Earth. So their team is, is studying few-body physics, how do these ultracold gases behave in space, how does the, the so-called three-body problem with three particles being bound into a state that’s not, not classically allowed or allowed for two particles, how does that behave at the ultra-low energies that we’re able to achieve in space? And so there’s quite a few very broad studies that are, that are opened up with CAL. I’d say each of the PIs are exploring something completely different but, and utilizing microgravity in very unique, unique ways.
Host: Yeah, you, you, you hear, you hear that, right, you hear that you’ve, you’ve spent some, so much time developing this, this facility and there’s so much interest, and this seems to be just a, a very unique thing, having this microgravity lab in, in space to, to do something like this. That, that opportunity for researchers to, to look at that seems to be important to not just, you know, a few researchers but a very, a very large amount of the scientific community looking at ultracold atomic research. Nathan, you hear this about a lot of the, of research going on and, and what comes to mind is, is just the importance of, of microgravity as a place to, to do research; when you think about the opportunities of, of, you know, why we do research in space, and, and folks are thinking, you know, why, why do we do this, what are some of the things that you say to, to, to people who ask, you know, why, why space is an important place, low-Earth orbit is an important place to do, to do research?
Nathan Lundblad: Well, I think the first answer I usually give depends on how old they are. You know, if they’re, if I’m talking to teenagers or younger, just the fact that we’re doing it in space immediately is justification in and of itself, just because, you know, I think there’s a visceral understanding of that, that, that, that space is a very intriguing place to go. But thinking about it more realistically about why we actually want to be up there, I think of being in space or being in, in orbit around the Earth as being the ultimate sort of clean laboratory for us. All these physics experiments that we’re trying to do on Earth, in general, we’re trying to isolate and create the, the most pristine lab environments that we can that are free from extraneous forces, extraneous influences that might hide the results that we’re trying to uncover or hide the, the physics that we’re trying to figure out. And by going into free fall and, you know, potentially later on exploiting the vacuum of space, you can actually get the, that sort of clean lab or sort of pristine lab quality without having a struggle for it on Earth. It just comes with the territory of being in orbit, in space. The other things that I, I like about moving toward a space-borne physics is the ability to just have a culture of science where we actually just set experiments to go and they just run and run and run, and we can kind of, we can use it as a remote laboratory that is either in a, the space station or in a free-flying satellite, or even in some kind of space probe where you design a mission, you set it and forget it, and you set it out, you know, out in the universe to go do its thing, and then years later you have the results that you were trying for without having to constantly monitor or struggle with it on Earth.
Host: So, so Jason, let me, let me, let me toss to you to, to, to wrap us up and, and thinking about that, leading off of, you know, why we do this research just, I wanted to end with this thing, with this idea of, of what’s next? You know, you, there’s been a lot of research, you’re using Cold Atom Lab, the design life I think I remember you saying was three years, so what are your hopes for not only Cold Atom Lab but for continued ultracold atomic research in space?
Jason Williams: Not only is this the first time we’re looking at this fifth state of matter called the Bose-Einstein condensate, in space, it’s also notable that unlike the other phases of matter that we know, Bose-Einstein condensates do not naturally occur, as far as we know, in the, in the universe, for, fully man-made phase. And so there is a lot to learn from this. But even building from that, and going from the fundamental physics questions, which are significant, I mean, with cold atoms we’re trying to look into fundamental physics to answer questions, tying together quantum mechanics and, and general relativity, trying to understand why, a potential link to what is the, the nature of dark matter and dark energy — there’s, there’s a number of investigations that have been pursued so far — and things like that. On the more applied side, quantum technologies are being built up and matured as a new class of technology and sensor that will influence our daily life in the future, I believe. The, the ability to use the control that we have with ultracold atoms and utilize unique quantum properties will bring us sensors and capabilities that I think are, can go far beyond what we can achieve with classical systems in the future. So things like atomic clocks have, have been, have changed our life as we know it right now. I mean, GPS (Global Positioning System) alone has been enabling for many applications. The next generations of sensors — those were just the beginning — the next generations of sensors are going to have levels of precisions that clocks will have to have, not only read out a time but it will be in relation to where you are on the Earth, for example, because it will be that sensitive to the gravitational redshift; applications for navigation; and, and yes, as we get ultra-high precision application and the ability to see new physics popping up, I think, will be really interesting in the future. So, so I, yeah, I see this as a, a very healthy subdiscipline that that’s growing up these studies in space, and I really hope what we find from Cold Atom Lab will, will have a very healthy heritage for the future.
Host: Yeah, absolutely. It’s very clear to me, right? There’s so much going on, so much to explore. And, and this idea that you mentioned of, of, you know, just, just really continuous research, there’s so much that you can just kind of keep going. It’s, there, there’s, it seems to be a good justification for, for why we’re doing this, for why we’re sending it up in space. There’s, there’s just a lot. Jason and Nathan, thank you so much for coming on Houston We Have a Podcast. I, I, I’m, I’m definitely not an expert in quantum mechanics, but you guys helped me to really understand what this is and, and why it’s important and just the applications are, are unbelievable. So thank you for coming on and talking about Cold Atom Lab and, and what you’re doing up there, and, and, and explain to us why, you know, this is, this is important stuff to do. I appreciate both of your times. Thanks.
Jason Williams: Thank you.
Nathan Lundblad: Thank you.
[Music]
Pat Ryan (Host): Hi, Pat Ryan to do the wrap-up today. Gary got Nathan and Jason to go into some great detail on quantum physics today; think they did a really good job explaining some complicated stuff. And you can learn more about Cold Atom Lab and other experiments on the International Space Station by going to research at NASA.gov/ISS; there’s a tab there called Research and Technology, it’ll tell you everything you need to know. I’ll remind you that you can go online to keep up with all things NASA at NASA.gov. Fact is, you can get all the NASA news you want delivered to you every week, if you go to NASA.gov/subscribe to sign up for the NASA newsletter. You can find the full catalog of all of our podcast episodes by going to NASA.gov/podcasts and scrolling to our name. You can also find all the other NASA podcasts right there at the same spot where you can find us, NASA.gov/podcasts. This episode was recorded on July 28th, 2022. Thanks to Will Flato, Gary Jordan, Heidi Lavelle, Belinda Pulido, Jaden Jennings, Bryana Quintana, and Chelsey Ballarte for their help with the production, and to Nathan Lundblad and Jason Williams for the enjoyable education on quantum physics. We’ll be back next week.