Sympathetic cooling
Encyclopedia
Sympathetic cooling is a process in which particles of one type cool particles of another type.
Typically, atomic ions that can be directly laser cooled
are used to cool nearby ions or atoms, by way of their mutual Coulomb interaction
. This technique allows cooling of ions and atoms that can't be cooled directly by laser cooling. This includes most molecular ion species, especially large organic molecules. However, sympathetic cooling is most efficient when the mass/charge ratios of the sympathetic- and laser-cooled ions are similar.
The cooling of neutral atoms in this manner was first demonstrated by Christopher Myatt et al. in 1997. Here, a technique with electric and magnetic fields were used, where atoms with spin in one direction were more weakly confined than those with spin in the opposite direction. The weakly confined atoms with a high kinetic energy
were allowed to more easily escape, lowering the total kinetic energy, resulting in a cooling of the strongly confined atoms.
Myatt et al. also showed the utility of their version of sympathetic cooling for the creation of Bose–Einstein condensate
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Typically, atomic ions that can be directly laser cooled
Laser cooling
Laser cooling refers to the number of techniques in which atomic and molecular samples are cooled through the interaction with one or more laser light fields...
are used to cool nearby ions or atoms, by way of their mutual Coulomb interaction
Coulomb barrier
The Coulomb barrier, named after Coulomb's law, which is named after physicist Charles-Augustin de Coulomb , is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo a nuclear reaction...
. This technique allows cooling of ions and atoms that can't be cooled directly by laser cooling. This includes most molecular ion species, especially large organic molecules. However, sympathetic cooling is most efficient when the mass/charge ratios of the sympathetic- and laser-cooled ions are similar.
The cooling of neutral atoms in this manner was first demonstrated by Christopher Myatt et al. in 1997. Here, a technique with electric and magnetic fields were used, where atoms with spin in one direction were more weakly confined than those with spin in the opposite direction. The weakly confined atoms with a high kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
were allowed to more easily escape, lowering the total kinetic energy, resulting in a cooling of the strongly confined atoms.
Myatt et al. also showed the utility of their version of sympathetic cooling for the creation of Bose–Einstein condensate
Bose–Einstein condensate
A Bose–Einstein condensate is a state of matter of a dilute gas of weakly interacting bosons confined in an external potential and cooled to temperatures very near absolute zero . Under such conditions, a large fraction of the bosons occupy the lowest quantum state of the external potential, at...
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