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Ultracold atom
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<p>In <a href="/facts/Condensed_matter_physics/EBVI5nmL">condensed matter physics</a>, an ultracold atom is an <a href="/facts/Atom/FoQ4kGN5">atom</a> with a <a href="/facts/Temperature/QyGe4gmj">temperature</a> near <a href="/facts/Absolute_zero/U3UyPl2K">absolute zero</a>. At such temperatures, an atom's <a href="/facts/Quantum_mechanics/BRc3Mzgr">quantum-mechanical</a> properties become important, especially through what's known as a <a href="/facts/Superfluidity/QuePDujN">"superfluid"</a>, such as <a href="/facts/Superfluid_helium-4/J0YToKcL">Superfluid Helium 4</a>. </p><p>To reach such low temperatures, a combination of several techniques typically has to be used. First, atoms are trapped and pre-cooled via <a href="/facts/Laser_cooling/hU2c6tdk">laser cooling</a> in a <a href="/facts/Magneto-optical_trap/thqk1QsG">magneto-optical trap</a>. To reach the lowest possible temperature, further cooling is performed using <a href="/facts/Magnetic_evaporative_cooling/vHkRopRL">evaporative cooling</a> in a <a href="/facts/Magnetic_trap_(atoms)/rrx8gGLH">magnetic</a> or <a href="/facts/Optical_tweezers/wsPxwmX6">optical trap</a>. Several Nobel prizes in physics are related to the development of the techniques to manipulate quantum properties of individual atoms (e.g. 1989, 1996, 1997, 2001, 2005, 2012, 2018). </p><p>Experiments with ultracold atoms study a variety of phenomena, including <a href="/facts/Quantum_phase_transition/XP5W2kYs">quantum phase transitions</a>, <a href="/facts/Bose%25E2%2580%2593Einstein_condensate/76peCwfW">Bose–Einstein condensation</a> (BEC), bosonic <a href="/facts/Superfluidity/QuePDujN">superfluidity</a>, <a href="/facts/Quantum_magnetism/nrfq6B17">quantum magnetism</a>, many-body spin dynamics, <a href="/facts/Efimov_state/2jjxkor1">Efimov states</a>, <a href="/facts/BCS_theory/KmlyhxPS">Bardeen–Cooper–Schrieffer (BCS) superfluidity</a> and the BEC–BCS crossover. Some of these research directions utilize ultracold atom systems as <a href="/facts/Quantum_simulator/x5fYot4j">quantum simulators</a> to study the physics of other systems, including the unitary Fermi gas and the <a href="/facts/Ising_model/lvBpj2h1">Ising</a> and <a href="/facts/Hubbard_model/5pphLNde">Hubbard</a> models. Ultracold atoms could also be used for realization of quantum computers. </p>