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Doppler cooling

When the red frequency detuning of the laser radiation is optimal for cooling purposes, that is, when Z = — 7, the temperature T, reaches the minimum value given by eqn (5.3), which usually lies in the millikelvin range. As stated earlier, the temperature Td is usually referred to as the Doppler cooling limit. [Pg.77]

Another ultimate temperature, determined by the recoil energy R (eqn 2.22) is defined by [Pg.77]

The fluctuations of the velocity and coordinates of an atom cause it to move in a diffusive fashion. This will take place if the length of the path the atom travels during a time t I/7 is much smaller than the size of its region of interaction with the field. Such a diffusive motion of the atom is well described by the Fokker-Planck equation (Minogin 1980). Diffusive redistribution of atomic velocities has been observed in an atomic beam propagating in a counterrunning light wave (Balykin et al. 1981). In the three-dimensional case, the diffusive motion of the atom takes place in the space of both velocities and coordinates. It is similar to the motion of a particle in a viscous medium and has therefore been termed optical molasses (Chu et al. 1985). [Pg.77]

In accordance with the above temperature-scale estimates (Fig. 5.4), it is convenient to consider consecutively the cooling of atoms first to the Doppler limit Td, then sub-Doppler cooling to Tree, and finally subrecoil cooling. Various mechanisms for cooling atoms in light fields of various configurations are considered below in the same sequence. The reader can find more detailed analysis in the book by Metcalf and van der Straten (1999). [Pg.77]

The Zeeman technique for compensating for the Doppler shift is to use the Zeeman shift of the atomic transition frequency while keeping constant the frequency of the cooling radiation. The Zeeman technique is applicable to cooling by means of t+- or (T -polarized radiation. In a magnetic field directed along the atomic beam axis z, the laser light is in resonance with the atomic transition under the condition [Pg.79]


However, die atom will not cool indefinitely. At some point die Doppler cooling rate will be balanced by die heating rate coming from die iiiomentum fluctuations of die atom absorbing and re-emitting photons. Setting diese... [Pg.2461]

Equation (Cl.4.35) yields two remarkable predictions first, tliat tire sub-Doppler friction coefficient can be a big number compared to since at far detuning Aj /T is a big number and second, tliat a p is independent of tire applied field intensity. This last result contrasts sharjDly witli tire Doppler friction coefficient which is proportional to field intensity up to saturation (see equation (C1.4.24). However, even tliough a p looks impressive, tire range of atomic velocities over which is can operate are restricted by tire condition tliat T lcv. The ratio of tire capture velocities for Doppler versus sub-Doppler cooling is tlierefore only uipi/uj 2 Figure Cl. 4.6 illustrates... [Pg.2465]

Figure C 1.4.6. Comparison of capture velocity for Doppler cooling and Tin-periD-lin sub-Doppler cooling. Notice tliat tire slope of tire curves, proportional to tire friction coefficient, is much steeper for tire sub-Doppler mechanism. (After [17].)... Figure C 1.4.6. Comparison of capture velocity for Doppler cooling and Tin-periD-lin sub-Doppler cooling. Notice tliat tire slope of tire curves, proportional to tire friction coefficient, is much steeper for tire sub-Doppler mechanism. (After [17].)...
MOT Magneto Optical Trap. The well established technique for Doppler cooling and trapping of a thermal cloud of cold atoms. [Pg.675]

DOPPLER COOLING The first ideas for laser cooling of atoms [6] and ions [7] were published in 1975. The basic idea of what is now called Doppler cooling can be understood by referring to the famous picture. Here we see a typical atomic resonance curve, which we can take to show the rate at which an atom... [Pg.19]

SUB-DOPPUIR COOLING In 1988 the NIST-Gaithersburg group made careful measurements of the temperature of atoms laser cooled in optical molasses, cind found temperatures significantly below the Doppler cooling limit 113). The initial measurements on laser cooled sodium atoms gave temperatures of about 40 pK, about six times lower tham the predicted lower limit of 240 pK. [Pg.20]

Atoms in an optical trap (Doppler cooling Wineland, et al., 1978 optical molasses Chu, et al., 1986 magneto-optic trap Steane and Foot, 1991 Helmerson, et al., 1992) are confined and cooled to translational temperatures on the order of << 1 mK. Ultracold collisions between such trapped atoms permit the recording of bound<—free spectra with resolution limited only by the translational temperature (1 mK, which corresponds to a frequency resolution of 7 x 10-4 cm-1) (Julienne and Mies, 1989 Lett, et al., 1995 Burnett, et al., 2002). This makes spectroscopically accessible the extremely long-range regions of potential energy curves (R >10A 5Re) and otherwise only indirectly observable weakly bound or repulsive electronic states. [Pg.43]

For small ion velocities the Doppler cooling force in Equations 10.11 and 10.12 can be approximated by a viscous damping force that is proportional to velocity, Pooppd =. where Y is a constant that depends on the laser wavelength, inten-... [Pg.303]

In this section, various effects that can limit the accuracy of the SCSI-MS technique are considered. In particular, deviations from the idealized case considered in Section 10.3.4, due to finite size motional amplitudes and the effects of the Doppler cooling force will be discussed. [Pg.312]

The effects of anharmonic terms have been sought experimentally by measuring the COM mode frequency at different amplitudes for two " Ca ions. Because the non-linearity of the Coulomb force does not affect the oscillation frequency in this case, any amplitude dependence should be due to either anharmonicity or the nonlinear velocity dependence of the Doppler cooling force as discussed in Section 10.5.1. As shown in Figure 10.7, at amplitudes between 15 pm and 35 pm, the measured COM frequencies near 95.625 kHz differ by less than 20 Hz and are equal within the error bars. Hence, at least at the level of 2 x 10" anharmonic effects can be ignored. Furthermore, if anharmonic effects were significant, a frequencypulling effect should have been apparent, but no such effect was observed. [Pg.316]


See other pages where Doppler cooling is mentioned: [Pg.2456]    [Pg.2458]    [Pg.2462]    [Pg.2462]    [Pg.2462]    [Pg.2463]    [Pg.2465]    [Pg.2467]    [Pg.470]    [Pg.549]    [Pg.915]    [Pg.935]    [Pg.470]    [Pg.549]    [Pg.591]    [Pg.20]    [Pg.20]    [Pg.21]    [Pg.23]    [Pg.33]    [Pg.49]    [Pg.69]    [Pg.451]    [Pg.2456]    [Pg.2458]    [Pg.2461]    [Pg.2462]    [Pg.2462]    [Pg.2462]    [Pg.2463]    [Pg.2465]    [Pg.2467]    [Pg.303]    [Pg.312]    [Pg.252]   
See also in sourсe #XX -- [ Pg.72 , Pg.82 , Pg.83 , Pg.104 ]




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Atoms Doppler cooling

Doppler

Doppler cooling force

Doppler cooling limit

Doppler laser cooled

Laser polarization gradient cooling below the Doppler limit

Sub-Doppler cooling

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