What are the circumstances which led you to your work?

I got into the field when Carl Wieman invited me to work in his lab the summer before I started graduate school. Prior to that, I had planned to study general relativity. I enjoyed the lab work, however, and had at least some inkling of the potential importance the experiments would have. My situation was complicated by the fact that my girlfriend was at Rice, and after spending a year apart I decided to move there. Scientifically, I suppose that ended up being the wrong choice, but I can’t say I really regret it. I certainly feel that I got to do important work at Rice, even if we missed out on the Nobel. It has always been important to me to balance my personal and scientific lives, and at the time, moving was the right way to do that. Naturally enough, our relationship didn’t end up working out, but I did meet my wife in Houston, and I wouldn’t want it any other way.

  How much has this research advanced since you first started publishing on it?

The field of BEC research has exploded over the past eight years. There are now dozens of groups worldwide that have created condensates, and nearly all the analogs between them and superfluids have been observed, such as persistent vortices, resistanceless flow, and a sound-like excitation spectrum to name a few. The consequences of non-zero atomic interactions have been explored, and dual species condensates are being studied. The work has been extended to fermionic atoms (atoms that behave like regular electrons) to study a closer analog of the process that permits superconductivity in metals. And condensates have been used to create atomic "crystals," in which the atoms are uniformly distributed across a three-dimensional array of microscopic traps. To put the activity in perspective: I just finished reviewing nominations for the APS prize for the best doctoral thesis in atomic, molecular, and optical physics. About one-third of the nominations were for work in BEC or closely related fields. So progress has really been breathtaking, and has lived up to our highest expectations.

  Where do you see this research going 10 years from now?

The field has been moving so fast that it’s hard to imagine what things might be like in 10 years. One of the big directions now is a push for "BEC on a chip," in which the required lasers, optics, and electromagnets are integrated onto a single substrate that can be placed in a vacuum can. A simplification like this will be required if condensates are to have any kind of commercial or military applications. I imagine this might be coming to fruition in 10 years or so.

The connection between atomic physics and condensed-matter systems is certain to see much more growth. I am confident that within a few years, experiments will be able to load either bosonic or fermionic atoms into a nearly arbitrary lattice potential and observe their behavior. As the capability for more complex arrangements grows, it will start to strain the computational ability of condensed matter theory, which will be a valuable test for different approaches. The dream of those of us in atomic physics is that we will develop an atomic crystal with some particularly interesting property, and that materials scientists will be able to create a real crystal with a similar structure and observe the effect we predict.

Finally, I expect that the range of atomic and molecular species we can condense will have expanded dramatically, which might start to draw chemists into the field. This could have an interesting effect: the recent advances in ultra-fast laser technology have allowed chemists to make great strides by directly probing molecular dynamics in the time domain. It is possible that ultra-cold molecular samples could revitalize the more traditional approach of frequency domain spectroscopy, since many sources of spectral broadening are eliminated and, at least in principle, information about the quantum phase of the wave function can be obtained. This is more speculative, but perhaps it will be a research direction 10 years from now.

  What lessons would you draw from your work to share with the next generation of researchers?

The effort to achieve BEC in 7-Li was started at Rice long before the details of the atomic interactions were known. When we found that the interactions were attractive, the prospects for success seemed dim because of the instability problem. But we decided to keep going, so that we could see for ourselves what would happen. A bit later, when we came up with the idea that the condensate could be stabilized by the zero-point energy, the theorists we talked to didn’t agree. But we still kept going, and in the end we did obtain BEC. The lesson I learned from that is you can’t take theory too seriously; you always need to do the experiment to be sure what will happen.