Coherent matter waves

Abstract

I am delighted to be writing this Editorial for a very special issue of J. Phys. B: At. Mol. Opt. Phys. Studies of coherent matter waves and Bose-Einstein condensation are now an important and growing part of atomic, molecular and optical physics around the world. These investigations are giving us new insights into the nature of coherent assemblies of ultra-cold atoms. These mesoscopic systems, newly available in the laboratory, are accessible to first principles theory, making them a superb test ground for many-body physics. Articles in this issue show how this has driven the development of new quantitative techniques for the finite temperature quantum fields needed to represent trapped and partially condensed gases. The fact that condensates are trapped and inhomogeneous means one has to deal with matters glossed over in the homogeneous case. A good example is the scale lengths relevant for vortex formation that can be comparable to the size of the whole condensate. The dynamics of formation and evolution of these features, as well as many others, can also be accessed directly in real time. The ability to manipulate directly the state of a condensed gas has enabled experimentalists to perform an extraordinary range of observations of the many-body dynamics of condensates. The fact that the interactions between the particle are tuneable, using external fields, adds enormously to the range of issues we shall see explored in the next few years. In the years to come, I expect us to see a yet wider range of studies where molecular systems play an increasing role. The coupling of controlled radiation and matter wave fields will also, I am sure, produce broad new avenues for new investigations. The subject has brought together physicists from atomic and optical physics with others from different areas; in particular condensed matter physics. Indeed, this cross-fertilisation has been a real treat for those of us involved in the field. It is difficult not be excited about the possibilities for this rapidly advancing field!