Winners: Eric Cornell and Carl Wieman, who made the first condensate, and Wolfgang Ketterle (right). Credit: K. ABBOTT/UNIV. COLORADO; EPA/PA

Wolfgang Ketterle of the Massachusetts Institute of Technology (MIT) and Carl Wieman and Eric Cornell of JILA, an interdisciplinary research centre in Boulder, Colorado, have won this year's Nobel Prize in Physics for their work in making and understanding Bose–Einstein condensates (BECs).

This new form of matter, a strange state in which a group of atoms behaves as a single particle, was first created in 1995 by Wieman and Cornell by cooling atoms of rubidium to within less than a millionth of a degree of absolute zero. Ketterle's group at MIT managed to make a condensate only months later.

The theoretical existence of BECs was first proposed by Albert Einstein in 1924, building on work by the Indian physicist Satyendra Nath Bose. All particles are either bosons or fermions. Quantum theory says that no two fermions can occupy the same quantum state, but that any number of bosons can, in principle, exist in the same state. Einstein predicted that, at very low temperatures, all the particles in a sample of bosons — such as the rubidium atoms used by the JILA team — should fall into the same state and act as a single particle, later termed a BEC.

The realization of BECs was long-awaited, and Wieman and Cornell's 1995 paper (see Science 269, 198–201; 1995) caused a storm in the world of fundamental physics. Ketterle and his colleagues at MIT have subsequently clarified many of the properties of condensates. Together, the winners' work has made possible a host of other experiments that probe fundamental aspects of quantum theory.

Few prizes have been as widely predicted as this year's physics award. The original 1995 discovery was thought by many at the time to be worthy of a Nobel prize. Some physicists suspect that the physics prize in 1997, awarded to the pioneers of the atom-trapping technologies that Wieman, Cornell and Ketterle used to cool their atoms — while undoubtedly deserved in its own right — was also given to prepare the path for honouring the breakthroughs at JILA and MIT.

Research into BECs is still highly active. Jakob Reichel and colleagues at the Ludwig-Maximilians University in Munich, for instance, have recently created an 'atom chip' in which electromagnetic fields control the movement of a condensate hovering above an electronic circuit (see Nature 413, 498–501; 2001). BECs are also allowing the investigations of imperfectly understood quantum phenomena such as entanglement (see Nature 413, 400–403; 2001). Entanglement will be one of the key features of future quantum computers.

Applications of the work are currently distant, although several possibilities exist. “I'm sure fascinating applications will happen,” says Claude Cohen-Tannoudji of the École Normale Supérieure in Paris, one of the 1997 laureates. He cites the example of atom lasers, in which a beam of atoms from a condensate is used to build high-precision structures.

The Nobel chemistry prize was announced after Nature went to press. For coverage, see → http://www.nature.com/nature/news/011011.html