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The Doppler temperature is the minimum temperature achievable with Doppler cooling. When a photon is absorbed by an atom counter-propagating to the light source, its velocity is decreased by momentum conservation. When the absorbed photon is spontaneously emitted by the excited atom, the atom receives a momentum kick in a random direction.
Sub-Doppler cooling is a class of laser cooling techniques that reduce the temperature of atoms and molecules below the Doppler cooling limit. In experiment implementation, Doppler cooling is limited by the broad natural linewidth of the lasers used in cooling. [ 1] Regardless of the transition used, however, Doppler cooling processes have an ...
While Doppler cooling lowers the translational temperature of a sample, anti-Stokes cooling decreases the vibrational or phonon excitation of a medium. This is accomplished by pumping a substance with a laser beam from a low-lying energy state to a higher one with subsequent emission to an even lower-lying energy state.
Polarization gradient cooling (PG cooling) is a technique in laser cooling of atoms. It was proposed to explain the experimental observation of cooling below the doppler limit. [1] Shortly after the theory was introduced experiments were performed that verified the theoretical predictions. [2] While Doppler cooling allows atoms to be cooled to ...
In general, the recoil temperature is below the Doppler cooling limit for atoms and molecules, so sub-Doppler cooling techniques such as Sisyphus cooling [2] are necessary to reach it. For example, the recoil temperature for the D 2 lines of alkali atoms is typically on the order of 1 μK, in contrast with a Doppler cooling limit on the order ...
It is a type of laser cooling of atoms used to reach temperatures below the Doppler cooling limit. This cooling method was first proposed by Claude Cohen-Tannoudji in 1989, [1] motivated by earlier experiments which observed sodium atoms cooled below the Doppler limit in an optical molasses. [2]
Temperatures achieved in a MOT can be as low as several microkelvin, depending on the atomic species, which is two or three times below the photon recoil limit. However, for atoms with an unresolved hyperfine structure, such as 7 Li, the temperature achieved in a MOT will be higher than the Doppler cooling limit.
Resolved sideband cooling. Resolved sideband cooling is a laser cooling technique allowing cooling of tightly bound atoms and ions beyond the Doppler cooling limit, potentially to their motional ground state. Aside from the curiosity of having a particle at zero point energy, such preparation of a particle in a definite state with high ...