National Enterprise for nanoScience and nanoTechnology, Istituto Nanoscienze-CNR, and Scuola Normale Superiore, I-56126 Pisa, Italy.
Science. 2011 Jun 3;332(6034):1176-9. doi: 10.1126/science.1204333.
Artificial crystal lattices can be used to tune repulsive Coulomb interactions between electrons. We trapped electrons, confined as a two-dimensional gas in a gallium arsenide quantum well, in a nanofabricated lattice with honeycomb geometry. We probed the excitation spectrum in a magnetic field, identifying collective modes that emerged from the Coulomb interaction in the artificial lattice, as predicted by the Mott-Hubbard model. These observations allow us to determine the Hubbard gap and suggest the existence of a Coulomb-driven ground state.
人工晶体格子可以用来调整电子之间的排斥库仑相互作用。我们将电子捕获在一个纳米制造的具有蜂窝状结构的格子中，这些电子被限制在砷化镓量子阱的二维气体中。我们在磁场中探测激发谱，从人工格子中的库仑相互作用中识别出了集体模式，这与莫特-哈伯德模型的预测相符。这些观察结果使我们能够确定哈伯德能隙，并表明存在一个由库仑驱动的基态。
