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Copyright by Kirsten Viering 2006 - Raizen Lab - The University of ...

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where m is the atomic mass. By setting ∆xsp = ∆xacc one finds the optimal pulse<br />

duration<br />

Tacc =<br />

2m<br />

F 2<br />

1/3<br />

and the acceleration limited resolution thus becomes<br />

∆xacc =<br />

2<br />

2mF<br />

(5.6)<br />

1/3<br />

. (5.7)<br />

Let us assume that only the final state is shifted <strong>by</strong> the potential. <strong>The</strong> transition<br />

between the initial state |i〉 and the final state | f 〉 can occur at any time during the pulse<br />

time T, and so the uncertainty in the final momentum <strong>of</strong> the atoms is ∆p = FT. Simple<br />

multiplication with the spectral resolution limit (eq. 5.2) leads to the fundamental limit<br />

given <strong>by</strong> the uncertainty relation between space and momentum<br />

µm<br />

5.3 Raman transitions in a three level atom<br />

∆x∆p = . (5.8)<br />

<strong>The</strong> total electro-magnetic field driving a stimulated Raman transition can be described<br />

<strong>by</strong> the sum <strong>of</strong> the two individual light beams with frequencies ω1 and ω2,<br />

E(r, t) = 1<br />

2 ·<br />

<br />

E1 · e i(k·r−ω1t) + E1 · e −i(k·r−ω1t) + E2 · e i(k·r−ω2t) + E2 · e −i( <br />

k·r−ω2t)<br />

. (5.9)<br />

<strong>The</strong>re exist three possible configurations <strong>of</strong> a three-level system with the initial<br />

state |i〉, an intermediate state |I〉 and a final state | f 〉, that is driven <strong>by</strong> a two-photon pro-<br />

cess, usually called the ”ladder”, ”V” or ”lambda” configurations, which are schemat-<br />

ically shown in fig. 5.3 [26]. A stimulated Raman transition between two hyperfine<br />

levels <strong>of</strong> the ground state corresponds to the Λ-configuration.<br />

29

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