论文标题
固体中高谐波产生的半导体Bloch方程的结构和激光仪
Structure- and laser-gauges for the semiconductor Bloch equations in high-harmonic generation in solids
论文作者
论文摘要
半导体BLOCH方程(SBE)通常用于凝结物质中强场激光器相互作用的模拟。在没有反转或时间反转对称性的系统中,浆果连接和过渡偶极相(TDP)必须包括在SBE中,而SBE则需要为Bloch状态构建平滑且周期性的结构规。在这里,我们说明了这种用于拓扑琐碎系统的结构规结构的一般方法。此外,我们研究了长度和速度测量值的SBE,并讨论了它们在高谐波生成(HHG)过程中的优势和缺点。我们发现,如果我们需要将电流进行分离或分离为带间和内的贡献,则长度量规SBE在计算上更有效。在无需驱动的计算和仅需要总电流的情况下,速度量规SBE独立于结构规范,并且在计算上更有效。我们采用两个系统作为数值示例来突出我们的发现:ZnO的一维模型和2D单层六角形硝化硼(H-BN)。 SBE中H-BN的浆果连接或TDP的粘附性导致非物理HHG光谱。当前工作中的结构和激光规范的考虑不限于HHG过程,并且适用于所有具有SBE的强场仿真。
The semiconductor Bloch equations (SBEs) are routinely used for simulations of strong-field laser-matter interactions in condensed matter. In systems without inversion or time-reversal symmetries, the Berry connections and transition dipole phases (TDPs) must be included in the SBEs, which in turn requires the construction of a smooth and periodic structure gauge for the Bloch states. Here, we illustrate a general approach for such a structure-gauge construction for topologically trivial systems. Furthermore, we investigate the SBEs in the length and velocity gauges, and discuss their respective advantages and shortcomings for the high-harmonic generation (HHG) process. We find that in cases where we require dephasing or separation of the currents into interband and intraband contributions, the length gauge SBEs are computationally more efficient. In calculations without dephasing and where only the total current is needed, the velocity gauge SBEs are structure-gauge independent and are computationally more efficient. We employ two systems as numerical examples to highlight our findings: an 1D model of ZnO and the 2D monolayer hexagonal boron nitride (h-BN). The omittance of Berry connections or TDPs in the SBEs for h-BN results in nonphysical HHG spectra. The structure- and laser-gauge considerations in the current work are not restricted to the HHG process, and are applicable to all strong-field matter simulations with SBEs.