Bose-Einstein condensate

A Bose-Einstein condensate is a gaseous superfluid phase formed by atoms cooled to temperatures very near to absolute zero. The first such condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder, using a gas of rubidium atoms cooled to 170 nanokelvins (nK). Under such conditions, a large fraction of the atoms collapse into the lowest quantum state, producing a superfluid.

Discovery

In 1938, Pyotr Kapitsa, John Allen and Don Misener discovered that helium-4 became a new kind of fluid, now known as a superfluid, at temperatures below 2.2 kelvins (K). Superfluid helium has many unusual properties, including zero viscosity (the ability to flow without dissipating energy) and the existence of quantized vortices. It was quickly realized that the superfluidity was due to Bose-Einstein condensation of the helium-4 atoms, which are bosons. In fact, many of the properties of superfluid helium also appear in the gaseous Bose-Einstein condensates created by Cornell, Wieman and Ketterle (see below). However, superfluid helium-4 is not commonly referred to as a "Bose-Einstein condensate" because it is a liquid rather than a gas, which means that the interactions between the atoms are relatively strong. The original Bose-Einstein theory has to be heavily modified in order to describe it.

Related Topics:
1938 - Pyotr Kapitsa - John Allen - Don Misener - Helium-4 - Superfluid - Viscosity

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The first "true" Bose-Einstein condensate was created by Cornell, Wieman, and co-workers at JILA on June 5, 1995. They did this by cooling a dilute vapor consisting of approximately 2000 rubidium-87 atoms to 170 nK using a combination of laser cooling (a technique that won its inventors Steven Chu, Claude Cohen-Tannoudji, and William D. Phillips the 1997 Nobel Prize in Physics) and magnetic evaporative cooling. About four months later, an independent effort led by Wolfgang Ketterle at MIT created a condensate made of sodium-23. Ketterle's condensate had about a hundred times more atoms, allowing him to obtain several important results such as the observation of quantum mechanical interference between two different condensates. Cornell, Wieman and Ketterle won the 2001 Nobel Prize for their achievement.

Related Topics:
JILA - June 5 - 1995 - Rubidium-87 - Laser cooling - Steven Chu - Claude Cohen-Tannoudji - William D. Phillips - 1997 - Nobel Prize in Physics - Magnetic evaporative cooling - Wolfgang Ketterle - MIT - Sodium-23 - Quantum mechanical - Interference - 2001

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The initial results by the JILA and MIT groups have led to an explosion of experimental activity. For instance, the first molecular Bose-Einstein condensates were created in November 2003 by teams surrounding Rudolf Grimm at the University of Innsbruck, Deborah S. Jin at the University of Colorado at Boulder and Wolfgang Ketterle at MIT. Jin also went on to create the first fermionic condensate.

Related Topics:
Molecular - 2003 - Rudolf Grimm - University of Innsbruck - Deborah S. Jin - University of Colorado at Boulder - Wolfgang Ketterle - MIT - Fermionic condensate

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Bose-Einstein condensates are extremely fragile, compared to other states of matter more commonly encountered. The slightest interaction with the outside world can be enough to warm them past the condensation threshold, causing them to break back down into individual atoms again; it is likely to be some time before any practical applications are developed for them.

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