Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Phys Rev Lett. 2014 Apr 11;112(14):146804. doi: 10.1103/PhysRevLett.112.146804. Epub 2014 Apr 10.
The gapless edge modes of the quantum spin Hall insulator form a helical liquid in which the direction of motion along the edge is determined by the spin orientation of the electrons. In order to probe the Luttinger liquid physics of these edge states and their interaction with a magnetic (Kondo) impurity, we consider a setup where the helical liquid is tunnel coupled to a semiconductor quantum dot that is excited by optical absorption, thereby inducing an effective quantum quench of the tunneling. At low energy, the absorption spectrum is dominated by a power-law singularity. The corresponding exponent is directly related to the interaction strength (Luttinger parameter) and can be computed exactly using boundary conformal field theory thanks to the unique nature of the quantum spin Hall edge.
无带隙边缘模式的量子自旋霍尔绝缘体形成了一种螺旋液体，其中电子的运动方向由自旋方向决定。为了探测这些边缘态的 Luttinger 液体物理及其与磁（Kondo）杂质的相互作用，我们考虑了一种设置，其中螺旋液体通过隧道耦合到半导体量子点，该量子点通过光吸收而被激发，从而有效地对隧道进行量子猝灭。在低能下，吸收光谱主要由幂律奇异点主导。相应的指数直接与相互作用强度（Luttinger 参数）相关，并可以通过边界共形场理论精确计算，这要归功于量子自旋霍尔边缘的独特性质。
