Bose-Einstein Condensates - Interview with Randy Hulet

n our analysis of Bose-Einstein condensate research, Dr. Randy Hulet ranked at #8 among scientists publishing in this field over the past decade, with 24 papers cited a total of 2,647 times. In the ISI Essential Science Indicators Web product, Dr. Hulet has 35 papers cited a total of 3,036 times to date in the field of Physics. His most-cited paper, "Evidence of Bose-Einstein condensation in an atomic gas with attractive interactions," (Phys. Rev. Lett. 75[9]: 1687-90, 28 August 1995), ranks at #3 in our list of the top 20 papers in the field, with 1,262 total citations. Dr. Hulet is the Fayez Sarofim Professor of Physics at Rice University in Houston, Texas.

Why do you think your work is highly cited?

Bose-Einstein condensation (BEC) has become an extremely exciting and active area of research, and many hundreds of papers on the subject are published every year. I was fortunate enough to have begun working towards an experimental realization of BEC several years before it was achieved, and our group was one of the first to get there. Also, the condensates that we made were different; they were made with lithium atoms, which attract each other. People had believed that atoms with attractive interactions could not Bose condense, but we showed that indeed they could. Since then, we have used a fermion isotope of lithium to study quantum degenerate Fermi gases. These papers have also received a great deal of interest.

What are the circumstances which led you to your work?

“…contrary to a long-held belief, we showed that atoms with attractive interactions can form Bose-Einstein condensates.”

I had been a post-doc with Dr. David Wineland at NIST in Boulder, Colorado. I learned the technique of laser cooling of atoms from Dr. Wineland, who is one of the inventors of the technique. When I began my own research program at Rice University, I proposed to use laser cooling to make a Bose-Einstein condensate of lithium atoms. Lithium seemed the best candidate to me because it was light (this turned out not to be so important), and it had both Bose and Fermi isotopes. We soon learned that laser cooling alone was not going to be sufficient to achieve the low temperatures needed (100 nano-Kelvin), but the field took off with the invention of an evaporative cooling technique.

Would you describe the significance of this work for your field?

First, contrary to a long-held belief, we showed that atoms with attractive interactions can form Bose-Einstein condensates. These condensates undergo a cataclysmic collapse, when the number of atoms exceeds a critical value. We also showed that when the condensate is confined in two dimensions but is free in the third, it will form solitons, localized wave-packets that do not spread in time. These experiments have produced a better understanding of quantum collective behavior. The significance of the fermion work is just emerging. Fermions can form correlated pairs, Cooper pairs, that underlie the phenomenon of superconductivity. Research with atomic Fermi gases, for which the experimental control is extraordinary and the theoretical capabilities remarkable, will lead to a better understanding of superconductivity, and perhaps to other quantum degenerate Fermi systems such as neutron stars or atomic nuclei.

Have any practical applications sprung from your work?

Not yet, but I feel that there will be applications for Bose-Einstein condensates in years to come. These will mainly be in the precision measurements (measurements of time and frequency, gravitation, and other inertial effects). We hope that Bose-Einstein solitons will be useful as the input source to an atom interferometer. Such a device could measure rotation or gravitational gradients with unprecedented precision. There may also be applications for atom lasers made from Bose-Einstein condensates.

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

I see the quantum gas field, which has its origins in atomic physics, merging with condensed matter physics. Many of the paradigms of modern condensed matter physics, including spin-charge separation, Luttinger liquids, the Hubbard model, the T-J model of high temperature superconductivity, and many others, can be realized with great clarity in atomic gases. Because of the prominence that electrons play in condensed matter, fermions will lead the charge.

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

Work on interesting problems, even if they seem beyond current capabilities. Experimental progress can occur so quickly that it takes your breath away.

Randy Hulet, Ph.D.
Rice University
Houston, TX, USA

ESI Special Topics, January 2004
Citing URL - http://www.esi-topics.com/bose/interviews/RandyHulet.html