Two-body exceptional points in open dissipative systems

We study two-body non-Hermitian physics in the context of an open dissipative system depicted by the Lindblad master equation.Adopting a minimal lattice model of a handful of interacting fermions with single-particle dissipation,we show that the non-Hermitian effective Hamiltonian of the master equation gives rise to two-body scattering states with state-and interaction-dependent parity-time transition.The resulting two-body exceptional points can be extracted from the trace-preserving density-matrix dynamics of the same dissipative system with three atoms.Our results not only demonstrate the interplay of parity-time symmetry and interaction on the exact few-body level,but also serve as a minimal illustration on how key features of non-Hermitian few-body physics can be probed in an open dissipative many-body system.     

动力学淬火过程中的不动点及衍生拓扑现象

本文对近两年来有关淬火动力学过程中拓扑现象的研究做简要综述.这些动力学拓扑现象被动力学过程中的衍生拓扑不变量保护,与淬火前后体系的拓扑性质有密切关系.基于人工量子模拟平台的高度可控性,已在诸如超冷原子、超导量子比特、核磁共振、线性光学等众多物理体系中,通过对人工拓扑体系动力学过程的调控,观测到如动力学涡旋、动量-时间域的Hopf映射及环绕数、拓扑保护的自旋环结构、动力学量子相变、动量-时间斯格明子等诸多动力学拓扑现象.其中某些拓扑结构还可以在非幺正动力学淬火过程中稳定存在.这些研究将人们对拓扑物相的认识和研究从平衡态推广到非平衡动力学领域,具有重要的科学价值.     

二维三角格光子晶体等效非线性折射率系数研究

考虑光子晶体中场局域效应,在等效介质理论的基础上利用场平均法得到二维三角格光子晶体的等效折射率.该折射率与平面波展开法得到的结果非常吻合.考虑慢光效应对非线性效应的增强,引入慢光增强因子得到该光子晶体的等效非线性折射率系数.该光子晶体的等效非线性折射率系数表现出强烈的色散效应,即随归一化频率的增加而逐渐减小,达到最小值后迅速递增,体现了场局域效应和慢光效应对光子晶体中非线性效应的共同作用.本文研究对利用人工微结构调控光学非线性效应具有一定参考价值.     

Tuning Excitation Transport in a Dissipative Rydberg Ring

<正>We demonstrate the flexible tunability of excitation transport in Rydberg atoms, under the interplay of controlled dissipation and interaction-induced synthetic flux. Considering a minimum four-site setup, i.e., a triangular configuration with an additional output site, we study the transport of a single excitation,