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