Our group typically consists of one to three undergraduate students, two to four graduate students, and four to six post-doctoral researchers, making a total of eight to twelve members. Our work has produced on average about ten refereed publications a year. Of these, on average three per year were in Physical Review Letters. Occasionally, we published papers in Science because they were of particularly broad interest which extended beyond the Physics community. A significant fraction of our papers consists of detailed articles, mostly for Physical Review E and for the Journal of Low Temperature Physics.
We are very pleased that our former postdoctoral associates and graduate students have been quite successful in obtaining suitable positions after they completed their work with us. Some of them now have academic positions. Examples are Wing-Yim Tam (Associate Professor of Physics at Hongkong University of Science and Technology), Victor Steinberg (Harry de Jur Professor of Physics at the Weitzmann Institute in Israel), Robert Duncan (Professor of Physics at the University of New Mexico in Albuquerque, NM), Ingo Rehberg (Professor of Physics at the University of Bayreuth, Bayreuth, Germany), Tim Sullivan (Associate Professor of Physics and Chair at Kenyon College), Mike Dennin (Associate Professor of Physics at UC Irvine), Eberhard Bodenschatz (Professor of Physics at Cornell University), John de Bruyn (Professor of Physics, Memorial University of Newfoundland, Canada), Stephen Morris (Professor of Physics at the University of Toronto), and Mingming Wu (Assistant Professor at Occidental College). Others have staff positions at national labs (Christopher Meyer at NIST, Lori Goldner at NIST, Ning Li at LANL, Melora Larson at JPL, Feng-Chuan Liu at JPL). Others now hold productive industrial jobs (Alan Singsaas, Ken Babcock, Kristina Lerman , and Yu-Chou Hu).
We have been active in two distinct subfields of experimental condensed matter physics. Here we give a brief description. A more detailed account can be found via the links below.
(1.) Critical Phenomena near the superfluid transition in liquid Helium
The superfluid transition in liquid 4He is unique in that the resolution of the experimental measurement is not limited by sample quality but rather by experimental techniques. In this system, it is possible to test the predictions of the renormalization-group theory of critical phenomena at a highly quantitative level. In order to exploit this opportunity, we have developed new methods of temperature measurement which can resolve temperature changes of less than a nano-Kelvin. In addition to testing older theoretical predictions at a highly quantitative level, we find with this technique qualitatively new phenomena very close to the transition which have to do with surface and nonequilibrium effects upon critical phenomena. We are also engaged in a study of impurities in the form of aerogel (a few percent of intertwined strands of colloidal particles of SiO2) on the critical behavior of this system.
(2.) Pattern-Forming Nonlinear Systems.
In nonlinear dissipative systems subjected to an external stress R, a transition frequently occurs from a spatially uniform state to a state of reduced symmetry having a spatial structure with a characteristic wavelength, when R exceeds a critical value Rc. Examples include formation of convection rolls in a horizontal layer of fluid heated from below, Taylor vortices in flow between two concentric cylinders with the inner one rotating, and thermally or electrically induced convection in a nematic liquid crystal. Our group is investigating these systems in an effort to answer many important questions about the mechanism of pattern selection, the temporal evolution of patterns, the conditions for temporal periodicity or chaos, the role of boundaries, and the importance of external noise.