Giant Rydberg excitons in the copper oxide Cu2O
Giant Rydberg excitons in the copper oxide Cu2O
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DOI：
10.1038/nature13832
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发表时间：
2014-10-16
期刊：
影响因子：
64.8
通讯作者：
Bayer, M.
中科院分区：
文献类型：
--
作者：
Kazimierczuk, T.;Froehlich, D.;Bayer, M.
一个高度激发的原子，其电子已经移动到具有大主量子数的能级，是一个类似氢的物体，称为里德伯原子。里德伯原子的巨大尺寸导致了巨大的相互作用效应。监测这些相互作用为单量子水平上的原子和分子物理学提供了见解。激子是半导体中最基本的光学激发，由一个电子和一个带正电的空穴组成，是氢的凝聚态类似物。具有类似于里德伯原子的延伸的高度激发的激子是令人感兴趣的，因为它们可以使用微观能量势能景观以高精度在晶体中放置和移动。这种里德伯激子的相互作用可以允许形成有序的激子相或在量子水平上感测其周围的元激发。在这里，我们证明了里德堡激子的存在，在氧化铜Cu 2 O，与主量子数为n = 25大。这些状态具有超过两微米的巨大波函数扩展（即电子和空穴之间的平均距离），而基态的波函数扩展约为一纳米。这种激子之间的强偶极-偶极相互作用由阻断效应指示，其中一个激子的存在防止其附近的另一个激子的激发。
A highly excited atom having an electron that has moved into a level with large principal quantum number is a hydrogen-like object, termed a Rydberg atom. The giant size of Rydberg atoms(1) leads to huge interaction effects. Monitoring these interactions has provided in-sights into atomic and molecular physics on the single-quantum level. Excitons-the fundamental optical excitations in semiconductors(2), consisting of an electron and a positively charged hole-are the condensed-matter analogues of hydrogen. Highly excited excitons with extensions similar to those of Rydberg atoms are of interest because they can be placed and moved in a crystal with high precision using microscopic energy potential landscapes. The interaction of such Rydberg excitons may allow the formation of ordered exciton phases or the sensing of elementary excitations in their surroundings on a quantum level. Here we demonstrate the existence of Rydberg excitons in the copper oxide Cu2O, with principal quantum numbers as large as n = 25. These states have giant wavefunction extensions (that is, the average distance between the electron and the hole) of more than two micrometres, compared to about a nanometre for the ground state. The strong dipole-dipole interaction between such excitons is indicated by a blockade effect in which the presence of one exciton prevents the excitation of another in its vicinity.