Macroscopically ordered state in an exciton system
Macroscopically ordered state in an exciton system
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DOI：
10.1038/nature00943
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发表时间：
2002-08-15
期刊：
影响因子：
64.8
通讯作者：
Chemla, DS
中科院分区：
文献类型：
--
作者：
Butov, LV;Gossard, AC;Chemla, DS
有丰富的量子液体，如超导体，液氦和原子玻色-爱因斯坦凝聚体，表现出有序的涡旋阵列形式的宏观相干性（1-4）。然而，半导体中宏观有序电子态的实验观察仍然是一个具有挑战性和相对未探索的问题。实现这种状态的一种有希望的方法是使用激子，即可以在半导体系统中形成的电子和空穴的束缚对。在低密度下，激子是玻色粒子（5），在几开尔文量级的低温下，激子可以形成量子液体-即统计简并的玻色气体，甚至是玻色-爱因斯坦凝聚体（5-7）。本文报道了GaAs/AlGaAs耦合量子威尔斯阱中准二维激子气体的光致发光测量和宏观有序激子态的观察。我们的空间分辨测量揭示了环形发射图案分裂成圆形结构，形成长度达1 mm的周期性阵列。
There is a rich variety of quantum liquids-such as superconductors, liquid helium and atom Bose-Einstein condensates-that exhibit macroscopic coherence in the form of ordered arrays of vortices(1-4). Experimental observation of a macroscopically ordered electronic state in semiconductors has, however, remained a challenging and relatively unexplored problem. A promising approach for the realization of such a state is to use excitons, bound pairs of electrons and holes that can form in semiconductor systems. At low densities, excitons are Bose-particles(5), and at low temperatures, of the order of a few kelvin, excitons can form a quantum liquid-that is, a statistically degenerate Bose gas or even a Bose-Einstein condensate(5-7). Here we report photoluminescence measurements of a quasi-two-dimensional exciton gas in GaAs/AlGaAs coupled quantum wells and the observation of a macroscopically ordered exciton state. Our spatially resolved measurements reveal fragmentation of the ring-shaped emission pattern into circular structures that form periodic arrays over lengths up to 1 mm.