School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Phys Rev Lett. 2013 May 24;110(21):213005. doi: 10.1103/PhysRevLett.110.213005. Epub 2013 May 21.
The laser excitation of Rydberg atoms in ultracold gases is often described assuming that the atomic motion is frozen during the excitation time. We show that this frozen gas approximation can break down for atoms that are held in optical lattices or microtraps. In particular, we show that the excitation dynamics is in general strongly affected by mechanical forces among the Rydberg atoms as well as the spread of the atomic wave packet in the confining potential. This causes decoherence in the excitation dynamics-resulting in a dissipative blockade effect-that renders the Rydberg excitation inefficient even in the antiblockade regime. For a strongly off-resonant laser excitation-usually considered in the context of Rydberg dressing-these motional effects compromise the applicability of the Born-Oppenheimer approximation. In particular, our results indicate that they can also lead to decoherence in the dressing regime.
在超冷气体中，里德伯原子的激光激发通常是在假设原子运动在激发时间内被冻结的情况下进行描述的。我们表明，对于被束缚在光学晶格或微阱中的原子，这种冻结气体近似可能会失效。具体来说，我们表明，激发动力学通常会受到里德伯原子之间的机械力以及束缚势中原子波包的扩散的强烈影响。这会导致激发动力学中的退相干——产生耗散阻塞效应——即使在反阻塞 regime 中，也会使里德伯激发效率降低。对于通常在里德伯修饰背景下考虑的强非共振激光激发，这些运动效应会影响 Born-Oppenheimer 近似的适用性。具体来说，我们的结果表明，它们也可能导致修饰 regime 中的退相干。
