Adiabatic population transfer

It fill is section we show how strong fields can be used to adiabatically control 

Bulation transfer between bound states and, especially, how to achieve complete nlatidn transfer between such states. In doing so we describe realistic methods for control, introduce a number of useful methods in strong-field control, and pave 

The ability to induce complete population transfer between states is intimately linked to the concept of a trapped state, that is, a state that remains invariant under the action of cw irradiation. These states, which only change when the field changes, often enable one to guide a quantum system from one state to another, a phenomenon known as adiabatic passage (AP), first introduced in the context of magnetic resonance [282] and described in detail below. 

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Sensitivity Enhancement Techniques by Adiabatic Population Transfer. 134... 

The idea exploited by Demirplak and Rice is very simple Given a fleld that would generate adiabatic population transfer from a selected initial state to a selected final state if strong enough, but which does not generate complete population transfer because of lack of intensity, find another fleld, called the CDF, that when combined with the first field generates the state that would have been generated by a strictly adiabatic transformation. Demirplak and Rice show that the CDF exists, and they show how it can be calculated. 

For reference purposes, we consider first adiabatic population transfer in a subset of three states decoupled from the full manifold of states. This adiabatic transfer can be driven by STIRAP. The subset of states we consider consists of 1200000), 1300000) and 200020), and the population transfer is from 200000) to 1200020). In the following paragraph, we refer to these states as 11), 5 ), and 6), respectively. We note that state 210011) with energy 5658.1828 cm is nearly degenerate with state 1200020) with energy 5651.5617 cm . We refer to 1210011) as state 9). Since the transition moment coupling states 11) and 6) is one order of... 

Suppose now that either the pulsed field duration or the field strength must be restricted to avoid exciting unwanted process that compete with the desired population transfer, with the consequence that condition (3.71) cannot be met. In an actual SCCI2 molecule //jg is nonzero, although it is one order of magnitude smaller than //j 9 and //5a 9 as mentioned. This situation prompts us to seek a CDF that restores the adiabatic population transfer. The counter-diabatic Hamiltonian for //rwa(0 ill Eq- (3.68) is obtained by using Eqs. (3.7) and (3.70) it is [11]... 

The Kobrak-Rice scheme generates adiabatic population transfer to one of a pair of degenerate states in a manifold of five states. In the application to thio-phosgene, as is also the case in application to other systems, a subset of five states is abstracted from the fiill manifold of states, as shown in Figure 3.14. In this subset of states, in addition to the pump and Stokes fields connecting 11) 2), 2) 3), and 2) 4), respectively, a third field is used to connect 3) 5) and 4) 5) this field acts throughout the duration of both the pump and Stokes fields. When the frequencies of the transitions 3) 5) and 4) 5) are... 

Note that rj defines the interval between the Stokes and pump pulses all of the above results correspond to t] = 1. The i -dependence of the efficiency in the STIRAP+CDF control for FWHM and 2 (5) given in Table 3.3 is shown in Figure 3.22. The efficiency for > 1 is higher than the efficiency (about 0.57) in the STIRAP control for = 1 and the same FWHM, 2 (5). The time dependences of the STIRAP + CDFs are shown for = 5 in Figure 3.23a, and the time dependences of the populations of 3), 4), and 5) in the STIRAP + CDF control are exhibited in Figure 3.23b. The time dependences of the populations of 3), 4), and 5) are similar to those found for adiabatic population transfer in a manifold without the background states. 

M. Demirplak and S. A. Rice. Adiabatic population transfer with control fields. J. Phys. Chem. A, 107(46) 9937-9945(2003). 

J. R. Kuklinski, U. Gaubatz, F. T. Hioe, and K. Bergmann. Adiabatic population transfer in a three-level system driven by delayed laser pulses. Phys. Rev. A, 40(11) 6741-6744(1989). 

Applications of control using moderate fields are discussed in Chapters 9 to 11. These fields allow for new physical phenomena in both bound state and continuum problems, including adiabatic population transfer in both regimes, electromagneti-cally induced transparency in bound systems, as well as additional unimolecular and bimolecular control scenarios. 

N.V. Vitanov, S. Stenholm, Adiabatic population transfer via multiple intermediate states, Phys. Rev. A 60 (1999) 3820. 

T. Rickes, L.P. Yatsenko, S. Steurwald, T. Halfmann, B.W. Shore, N.V. Vitanov, et al.. Efficient adiabatic population transfer by two-photon excitation assisted by a laser-induced Stark shift, J. Chem. Phys. 113 (2001) 534. 

S. Kallush, YB. Band, Short-pulse chirped adiabatic population transfer in diatomic molecules, Phys. Rev. A 61 (2000) 041401. 

Section 7.3 presents results of the numerical calculations. It is shown that, for well-chosen pulse parameters, total adiabatic population transfer can be achieved, so that all the pairs of atoms with interatomic distances within a range defining a photoassociation window are transformed into bound molecules. An estimation of the total number of such photoassociated molecules is given. 

Effect of the chirp sign. Changing the sign of the chirp does not significantly change the results obtained for since total adiabatic population transfer within the PA window is effective and since the number of Rabi oscillations during the pulse (1.5) is small the final population transferred by the pulse... 

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