Time evolution of topological magneto-optics and superconducting qubits

拓扑磁光和超导量子位的时间演化

基本信息

批准号：
16F16027
负责人：
NORI FRANCO
金额：
$ 1.41万
依托单位：
Institute of Physical and Chemical Research
依托单位国家：
日本
项目类别：
Grant-in-Aid for JSPS Fellows
财政年份：
2016
资助国家：
日本
起止时间：
2016-10-07 至 2019-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16F16027/
关键词：
Nonlinear response topological insulators flat-band optical conductivity Kubo formula master equation disorder topological materials Gaussian quantum states topological

项目摘要

We study the nonlinear response to an external driving electric field E characterized by a conductivity tensor which depends on the magnitude of E. The quasiparticles (helical Dirac fermions) observed in topological insulators possess an important feature: the Fermi contours are circular for small acquire a snowflake shape at large values of the chemical potential. If a gap opens (e.g., by doping with magnetic impurities) the inversion symmetry is broken. We develop a nonlinear response theory based on a generalized Kubo formula to explain the frequency up-conversion in topological insulators.Flatbands, which may emerge as a consequence of symmetries or finetuning in certain tight-binding Hamiltonians, are characterized by a completely dispersionless single-particle energy spectrum. Remarkably, flat bands feature the existence of “compact localized states”, free of any dynamical evolution and with tailorable shape, the latter by judiciously superposing the entirely degenerate Bloch states. We start from the cross-stitch model that most simply describes a flat-band (FB) and a dispersive-band (DB). And consider the disorder effect by setting on-site energies with correlated random numbers. The disorder will induce decay from FB to DB together with dephasing in momentum space. This will limit the lifetime of the FB state.

我们研究对外部驱动电场 E 的非线性响应，其特征在于电导率张量取决于 E 的大小。在拓扑绝缘体中观察到的准粒子（螺旋狄拉克费米子）具有一个重要特征：费米轮廓是圆形的，对于小获得如果化学势值很大，就会出现雪花形状（例如，通过掺杂磁性杂质），反演对称性就会被打破。解释拓扑绝缘体中频率上转换的广义久保公式。平带可能是由于某些紧束缚哈密顿量的对称性或微调而出现的，其特征是完全无色散的单粒子能谱。值得注意的是，平带。特征是“紧凑局域态”的存在，没有任何动态演化，并且具有可定制的形状，后者是通过明智地叠加完全简并的布洛赫态来实现的。十字绣模型最简单地描述了平带（FB）和色散带（DB），并通过设置具有相关随机数的现场能量来考虑无序效应，无序会导致从 FB 到 DB 的衰减。动量空间的相移会限制 FB 状态的寿命。