量子点接触中的动态量子输运

Dynamical transport measurements of a quantum point contact

摘要:

实验测量量子点接触结构的动态量子输运. 观察到导纳的实部和虚部都出现明显的台阶, 为负值的虚部反应了器件的电感性响应的特性. 但是零磁场条件下的导纳坪台有波动, 这是背散射导致的结果. 外加磁场可以有效的抑制背散射, 改善坪台的平整程度, 实验观察到当磁场为0.3 T左右时就可以得到比较理想的坪台. 当磁场进一步增大时, 可以观察到磁耗散效应, 并且由此可以估算器件的零磁场子能带的间距.

Abstract:

We report the experimental measurements of dynamic quantum transport in a quantum point contact structure. Both the real and the imaginary parts of the admittance show significant steps, and the imaginary parts of the admittance reflect the inductive response of the time-dependent oscillating voltage. However, the plateaus around zero magnetic field are not perfect flat due to backscattering. The external magnetic field can effectively suppress backscattering and improve the quantity of the quantized steps. The flatter plateaus are observed when the magnetic field extends to 0.3 T. Continuing to increase the magnetic field, the magnetic depletion effect will play role, and thus the sub-band spacing of the zero magnetic field can be estimated.