Fast adiabatic passage

In an adiabatic fast passage experiment, the sweep rate is chosen so that no appreciable relaxation takes place during the sweep (the "fast condition), and the nuclear precession around He is always rapid compared with the rotation of He (the "adiabatic" condition). The first condition means that M remains constant in length during the sweep while the second condition ensures that whatever initial relationship the magtiz-ation had with respect to Hg remains throughout the sweep. In particular, if the nuclei were in thermal equilibrium with... 

Another technique for ADRF is identical to the first except that an adiabatic fast passage (section I.B.) to the center of the line is used to spin-lock rather than a phase manipulated pulse sequence. First the applied field is... 

The preparation of circular Rydberg levels require, in addition to the laser excitation, a stage of circularly polarized microwave photon absorptions performed by adiabatic fast passage in a directing electric field. ... 

Dinesh and Rogers [22,1] have also measured T and T2 for the proton in CHCl as a function of temperature (- 54°C to + 90 0. They employed an NMR Specialties multi-purpose NMR spectrometer. T2 was measured using the Carr-Purcell-Meiboom-Gill method and also by the adiabatic fast-passage method at room temperature. The sample of CHCl was carefully purified and degassed. The measured values around room temperature are... 

Fig. 9.2.7 Illustration of the fast adiabatic passage through resonance. The magnetization M follows the direction of the effective field The effective field in the rotating frame is the vector sum of the fictitious field Sbc and rf excitation field B. Both fields are applied in orthogonal directions. Because the fictitious field is proportional to the resonance offset S2, the magnitude of the fictitious field and thus the direction of the effective field can be changed by adjusting the resonance offset frequency S2.

V. A. Sautenkov, C. Y. Ye, Y. V. Rostovtsev, G R. Welch, and M. O. Scully. Enhancement of field generation via maximal atomic coherence prepared by fast adiabatic passage in Rb vapor. 

The formula nevertheless reflect the essential physics in nonadiabatic transition. The exponential dependence on parameters reflects the non-perturbative nature of this problem. The non-dimensional exponent hv Fi-F2 " hich represents adiabaticity, ensures the correct limiting behavior (the adiabatic limit v —> 0 and its opposite v — 00 correspond to P = 0 and P = 1, respectively). One also sees the correct scale in this problem for example, whether the passage velocity v is fast or not should be measured in unit V / h Fi — F2 ). Qualitative accuracy of this formula is known to be rather robust see for example, Ref. [445], in which they compare exact result with LZ formula as well as their proposed (surface hopping) method. These virtues are favorable for making rough estimate as well as constructing new guiding principle of one s study see, for example, Ref. [404] to see that the LZ estimate is still conceptually important even in the state-of-art studies. 

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