120 W Miller Ave, Stillwater, Oklahoma 74078, USA.
Institute for Quantum Science and Engineering, Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77845, USA.
Sci Rep. 2017 Mar 24;7:45015. doi: 10.1038/srep45015.
Finding new phase of matter is a fundamental task in physics. Generally, various phases or states of matter (for instance solid/liquid/gas phases) have different symmetries, the phase transitions among them can be explained by Landau's symmetry breaking theory. The topological phases discovered in recent years show that different phases may have the same symmetry. The different topological phases are characterized by different integer values of the Berry phases. By studying one dimensional (1D) trimer lattices we report new phases beyond topological phases. The new phases that we find are characterized by piecewise continuous Berry phases with the discontinuity occurring at the transition point. With time-dependent changes in trimer lattices, we can generate two dimensional (2D) phases, which are characterized by the Berry phase of half period. This half-period Berry phase changes smoothly within one state of the system while changes discontinuously at the transition point. We further demonstrate the existence of adiabatic pumping for each phase and gain assisted enhanced pumping. The non reciprocity of the pumping process makes the system a good optical diode.
发现物质的新相是物理学中的一个基本任务。通常，物质的各种相或状态（例如固体/液体/气体相）具有不同的对称性，它们之间的相变可以用 Landau 的对称性破缺理论来解释。近年来发现的拓扑相表明，不同的相可能具有相同的对称性。不同的拓扑相的特征在于 Berry 相的不同整数值。通过研究一维（1D）三聚体晶格，我们报告了超越拓扑相的新相。我们发现的新相的特征是 Berry 相具有分段连续，在相变点处发生不连续。随着三聚体晶格的时变，可以产生二维（2D）相，其特征是 Berry 相的半周期。在系统的一个状态内，这个半周期 Berry 相是平滑变化的，而在相变点处是不连续变化的。我们进一步证明了每个相的绝热泵送的存在，并获得了辅助增强泵送。泵送过程的非互易性使系统成为一个良好的光二极管。
