Recoil temperature
Encyclopedia
In laser cooling
, the Boltzmann constant times the recoil temperature is equal to the recoil energy deposited in a single atom initially at rest by the spontaneous emission
of a single photon
. It is defined as
where
is the wavevector of the light, 
is the mass of an atom, 
is Boltzmann's Constant and 
is Planck's Constant. It is typically on the order of 1 μK, and thus lower than the Doppler temperature. An example of a process where the recoil temperature can be reached is Sisyphus cooling
.
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...
, the Boltzmann constant times the recoil temperature is equal to the recoil energy deposited in a single atom initially at rest by the spontaneous emission
Spontaneous emission
Spontaneous emission is the process by which a light source such as an atom, molecule, nanocrystal or nucleus in an excited state undergoes a transition to a state with a lower energy, e.g., the ground state and emits a photon...
of a single photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
. It is defined as
where
is the wavevector of the light, is the mass of an atom, is Boltzmann's Constant and is Planck's Constant. It is typically on the order of 1 μK, and thus lower than the Doppler temperature. An example of a process where the recoil temperature can be reached is Sisyphus coolingSisyphus cooling
Sisyphus cooling is a mechanism through which atoms can be cooled using laser beams below the temperatures expected to be achieved by Doppler cooling. It comes about as a result of a polarization gradient created by two counter-propagating laser beams with orthogonal polarization...
.