Conductance Quantization in a Periodically Modulated Quantum Channel: backscattering and mode mixing

TL;DR

This paper investigates how periodic modulation in quantum channels can restore conductance quantization despite the presence of strong defects, highlighting the robustness of quantization under certain periodic structures.

Contribution

It demonstrates that periodic arrangements of double-stubs and constrictions can recover and maintain conductance quantization even with strong defects present.

Findings

Periodic double-stubs lead to remarkable conductance quantization.

Small separation between constrictions enhances quantization.

Quantization is robust in periodically modulated channels.

Abstract

It is known that the conductance of a quantum point contact is quantized in units of $2e^2/h$ and this quantization is destroyed by a non-adiabatic scatterer in the point contact, due to backscattering. Recently, it was shown [Phys. Rev. Lett. 71, 137 (1993)] that taking many non-adiabatic scatterers periodically in a quantum channel, the quantization can be recovered. We study this conductance quantization of a periodic system in the presence of a strong defect. A periodic arrangement of double-stubs give remarkable quantization of conductance. A periodic arrangement of double-constrictions also gives a very good quantization only when the separation between the constrictions is small. We conclude that conductance quantization of a periodically modulated channel is robust.