Boulier T, Magnan E, Bracamontes C, Maslek J, Goldschmidt E A, Young J T, Gorshkov A V, Rolston S L, Porto J V
Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA.
Laboratoire Charles Fabry, Institut dOptique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau cedex, France.
Phys Rev A (Coll Park). 2017 Nov;96(5). doi: 10.1103/physreva.96.053409. Epub 2017 Nov 13.
Strong dipole-exchange interactions due to spontaneously produced contaminant states can trigger rapid dephasing in many-body Rydberg ensembles [E. Goldschmidt ., PRL 116, 113001 (2016)]. Such broadening has serious implications for many proposals to coherently use Rydberg interactions, particularly Rydberg dressing proposals. The dephasing arises as a runaway process where the production of the first contaminant atoms facilitates the creation of more contaminant atoms. Here we study the time dependence of this process with stroboscopic approaches. Using a pump-probe technique, we create an excess "pump" Rydberg population and probe its effect with a different "probe" Rydberg transition. We observe a reduced resonant pumping rate and an enhancement of the excitation on both sides of the transition as atoms are added to the pump state. We also observe a timescale for population growth significantly shorter than predicted by homogeneous mean-field models, as expected from a clustered growth mechanism where high-order correlations dominate the dynamics. These results support earlier works and confirm that the time scale for the onset of dephasing is reduced by a factor which scales as the inverse of the atom number. In addition, we discuss several approaches to minimize these effects of spontaneous broadening, including stroboscopic techniques and operating at cryogenic temperatures. It is challenging to avoid the unwanted broadening effects, but under some conditions they can be mitigated.
由于自发产生的杂质态而导致的强偶极交换相互作用，会在多体里德堡系综中引发快速退相[E. 戈德施密特等人，《物理评论快报》116, 113001 (2016)]。这种展宽对于许多相干利用里德堡相互作用的提议，尤其是里德堡缀饰提议，有着严重影响。退相作为一个失控过程出现，其中第一个杂质原子的产生会促进更多杂质原子的产生。在此，我们用频闪方法研究这个过程的时间依赖性。利用泵浦 - 探测技术，我们产生过量的“泵浦”里德堡布居，并通过不同的“探测”里德堡跃迁来探测其效应。当原子被添加到泵浦态时，我们观察到共振泵浦速率降低，并且在跃迁两侧的激发增强。我们还观察到布居增长的时间尺度显著短于均匀平均场模型的预测，正如从高阶关联主导动力学的聚集增长机制所预期的那样。这些结果支持了早期的工作，并证实退相开始的时间尺度缩小了一个与原子数的倒数成比例的因子。此外，我们讨论了几种将自发展宽的这些效应最小化的方法，包括频闪技术和在低温下运行。避免不必要的展宽效应具有挑战性，但在某些条件下可以减轻这些效应。
