just one of many quantum fluid lab
things you may not understand

      We see various objects everyday, butÖ how are they staying together, how do they interact on a microscopic level (or smaller), and why isn't everything just melting into everything else, creating a large, unpleasant brownish-green puddle of sad existence?  You may not realize this (or fully understand it), but there is an entire field of physics devoted to such questions and their more complicated siblings. Physics professor Fred Ellis is currently the head of this lab, and his involvement stems from asking such seemingly simple, but actually quite complex questions.  After a pre-grad-school summer job working in a low temperature physics lab and performing various experiments, Ellis learned that "there are a lot of strange things in everyday physics that people don't understand", and became interested in the field.  A graduate of the University of Massachusetts, where he earned both a bachelor's in science and his PhD, Ellis was attracted to Wesleyan because of its combination of actual teaching and scientific research, and, having grown up and gone to school in Massachusetts, its New England location.  He's in his sixteenth year at Wes and has become head of the quantum fluid lab.  There had been a low-temperature physics history at Wesleyan before Ellis's arrival, but he and fellow heads of lab groups built their own labs and wound up quite independent of what came before them.
         Low-temperature physics can be difficult to explain, but I'll take a shot at it. First of all, quantum mechanics is a field of physics that deals with the manner in which objects behave on a microscopic scale, and how everything is made of individual, invisible particles.  Around eighty years ago, it was discovered that particles exhibited wave-like behavior, and low temperature physics brings matter into a wave-like state without having to operate on such a small scale; at a low enough temperature, the properties of any given material will adhere to those of quantum mechanics.   The fluid aspect is explored at the Wesleyan labs, among other places; fluids are cooled to a low enough temperature "so that the wave nature of the individual particles really takes overÖ It makes the whole fluid or whole collection of particles act in a similar wave-like fashion, that's not obvious in everyday experience," Ellis notes. That is to say, work at the quantum fluids lab allows scientists to observe larger versions of what goes on all around us, invisibly, all the time.
    There are, though, other quantum mechanics that are more obvious in everyday experience. For example, he cites magnetism, "a manifestation of the quantum nature of microscopic particles acting together to create a macroscopic field, or macroscopic thing that can be observed by large objects, by compass needles, things like thatÖ And just like magnetism, these quantum fluids have macroscopic fields associated with them, that do funny things at low temperatures.  It just turns out that room temperature is effectively a low enough temperature for magnetic spins-- little nuclear and electron spins of particles that they can align."
         Ellis cites a laser pointer as another everyday object that displays larger-scale quantum mechanics: "The laser beam is a column of light in which all of the light has been forced into exactly the same stateÖ the laser is a situation where light is actually acting like particles [instead of vice versa], and that makes protons, electrons, and photons all kind of the same, in some of the ways that they behave; the laser beam is getting all of the light to be in all of the same state.  A super-fluid is kind of like that: all of the particles are exactly in the same state.  So in some sense, a super-fluid and a laser are already very similar to each other."  One of his current experiments is an idea not previously proposed: taking this laser-like condensing of fluid particles and applying it to "acoustic modes." "I want to try to get the collective nature of superfluid to show itself in a vibrational state, like a guitar string vibratesÖ and I want to get the quantum mechanical macroscopic energy to show up in that vibrating state," placing it in an easier state to remove energy from, just as scientists can remove energy from lasers when it comes out in concentrated beams.   "All the property of a super-fluid is just kind of sitting there, quantum mechanically doing its thing, but there's nothing you can get out of it," says Ellis. "If I can do this with a vibrating state, I could get the same kinds of output, [and] extract some of the acoustical energy.  We're just trying it; it's very difficult.  We've been working on it for a year and a half now, unsuccessfully, but we're gonna get it-- these things take time."
         Low temperature quantum physics has an interesting combination of the ordinary and the extraordinarily complicated, and it is this duality that Ellis seems to enjoy about the subject: "There's some very simple concepts in physics, relatively simple I guess, that are still complete mysteries, as to how they fit into the overall picture in physicsÖ the field of condensed matter physics, which superfluids is part of, has a lot these situations simply because we're dealing with many, many particles acting together, so that's interesting to try to uncover better techniques to describe what's going on."  There is also a duality about his appreciation for Wesleyan: the opportunity to both do research and teach eager college students. "You need a school this size to really concentrate on the undergraduate experience, and yet have a graduate presence, which we really need as experimentalists to do our researchÖ the process of getting here was a long one, but I certainly very much enjoy being able to determine exactly what I'm doing, and not having someone else tell me what to do.  I can decide to do research on a particular thing, and spend a year and a half trying to do it, like I have, without pressures of a bottom line, of some CEO telling me I've got to get this product out!  It's a good way to do science."
 

perhaps you are intrigued and wish to visit the quantum fluids lab webpage: well, here it is!
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