Excitation of a symmetry broken state in an optical lattice of rubidium atoms

铷原子光学晶格中对称破缺态的激发

• 批准号: 53142000
• 负责人: Professor Dr. Andreas Hemmerich
• 金额: --
• 依托单位: Institut für Laser-Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/53142000?language=en
• 关键词: Excitation; symmetry; broken; state; optical

We propose to prepare a stationary quantum state with dx2-y2-geometry in a twodimensional optical square lattice of rubidium atoms. This state, characterized by alternating rotational flux in each unit cell, is excited by a simple stimulated Raman scattering process, which does not require internal atomic structure apart from a non-zero polarizability, thus permitting a straight forward experimental implementation. The proposed Raman-technique exploits the interference between two appropriate light fields with slightly different frequencies, in order to produce a two-dimensional square array of microscopic rotors, each applying angular momentum to a single unit cell of the lattice with alternating rotational direction for adjacent cells. In the framework of the Bose-Hubbard model, this Raman-coupling gives rise to a two-body ring exchange interaction, which should lead to novel quantum phases near the Mott-insulator phase. We will experimentally investigate the phase diagram of the system by studying the interference capability of the atoms in presence of the ring exchange interaction. Our findings will be confronted with calculations by condensed matter theorists at Utrecht University.

我们提出在二维光学正方晶格中制备具有dx ~ 2-y ~ 2-几何构型的铷原子定态量子态。这种状态，其特征在于在每个单元格交替旋转通量，激发一个简单的受激拉曼散射过程，它不需要内部原子结构除了一个非零的极化率，从而允许一个简单的实验实现。所提出的拉曼技术利用两个适当的光场之间的干涉与略有不同的频率，以产生一个二维正方形阵列的微观转子，每个应用角动量的晶格的一个单一的单元格与交替的旋转方向相邻的细胞。在玻色-哈伯德模型的框架中，这种拉曼耦合引起了两体环交换相互作用，这应该会导致莫特绝缘体相附近的新量子相。我们将通过研究原子在环交换相互作用下的干涉能力来实验研究系统的相图。我们的发现将与乌得勒支大学凝聚态理论家的计算结果进行比较。