Recoil temperature

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.^[1] It is defined as

$T_{recoil}=\frac{\hbar^2k^2}{2mk_B}$

where $k$ is the wavevector of the light, $m$ is the mass of an atom, $k_B$ is Boltzmann's Constant and $\hbar$ 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.

References

↑ Metcalf and van der Straten (1999). Laser Cooling and Trapping. New York: Spinger-Verlag. ISBN 0-387-98728-2.