Macroscopically ordered state in an exciton system

Article

关键词: COUPLED QUANTUM-WELLS;    CONDENSATION;    GAS;   

DOI  :  10.1038/nature00943

来源: SCIE

【 摘 要 】

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.

【 授权许可】

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