Nonequilibrium Phase Transition in a Dilute Rydberg Ensemble
Nonequilibrium Phase Transition in a Dilute Rydberg Ensemble
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DOI：
10.1103/physrevlett.111.113901
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发表时间：
2013-09-10
影响因子：
8.6
通讯作者：
Weatherill, K. J.
中科院分区：
文献类型：
--
作者：
Carr, C.;Ritter, R.;Weatherill, K. J.
我们演示了稀热原子气体中的非平衡相变。里德堡原子之间的共振偶极-偶极相互作用引起了里德堡原子低占据态和高占据态之间的相变。这种气体可以被认为是稀薄的，因为原子之间的距离远远大于用于激发它们的光学跃迁的波长。在频域中，我们观察到里德堡态的平均场移动，这导致了高于临界里德堡数密度的本征光学双稳态。在时间域中，我们观察到对系统扰动的恢复时间不同的临界减速，临界指数α=-0.53+/-0.10。高Rydberg占有率相的原子发射光谱为超辐射级联提供了证据。
We demonstrate a nonequilibrium phase transition in a dilute thermal atomic gas. The phase transition, between states of low and high Rydberg occupancy, is induced by resonant dipole-dipole interactions between Rydberg atoms. The gas can be considered as dilute as the atoms are separated by distances much greater than the wavelength of the optical transitions used to excite them. In the frequency domain, we observe a mean-field shift of the Rydberg state which results in intrinsic optical bistability above a critical Rydberg number density. In the time domain, we observe critical slowing down where the recovery time to system perturbations diverges with critical exponent alpha = -0.53 +/- 0.10. The atomic emission spectrum of the phase with high Rydberg occupancy provides evidence for a superradiant cascade.