The Bose-Einstein condensate (BEC) is a state of matter in which a large number of atoms, cooled to near absolute zero, occupy the same quantum state. This phenomenon, theoretically predicted by Satyendra Nath Bose (1894-1974) and Albert Einstein (1879-1955) in 1924-1925, was first observed experimentally in 1995 by Eric Cornell (1961-) and Carl Wieman (1951-) using rubidium.
In a Bose-Einstein condensate, atoms collectively behave as a single macroscopic wave, perfectly illustrating wave-particle duality. Atomic density and quantum coherence allow the observation of phenomena such as superfluidity and interference on a macroscopic scale.
The typical temperature to achieve a Bose-Einstein condensate is on the order of nanokelvins (\(\approx 10^{-9}\, K\)). At this scale, the kinetic energy of the atoms is so low that quantum effects completely dominate their dynamics.
Main techniques include magnetic trapping and laser cooling. Atoms are first slowed by photon absorption and re-emission, then confined in magnetic or optical potentials to reach the temperatures required for condensation.
Bose-Einstein condensates allow the study of quantum physics at a macroscopic scale, simulation of astrophysical phenomena, and development of technologies such as ultra-precise interferometry, atomic clocks, and gravity sensors.
State | Typical Temperature | Quantum Behavior | Example |
---|---|---|---|
Solid | 300 K | Local quantum effects | Diamond |
Liquid | 300 K | Partial quantum effects | Liquid H₂O |
Gas | 300 K | Classical | O₂ gas |
Bose-Einstein Condensate | ≈ 10⁻⁹ K | Full macroscopic quantum coherence | Rubidium, Sodium |
Source: NIST – Bose-Einstein Condensates and Physics World – BEC 20 Years.
The Bose-Einstein condensate spectacularly illustrates how quantum physics can dominate the collective behavior of matter, opening the way to unprecedented experimental and technological applications.