Soft Disorder Effects in the Conductance Quantization in Quantum Point Contacts: Indirect Backscattering Statistics
Year: 1994
Type: preprint
Abstract: The breakdown of conductance quantization in a quantum point contact in the presence of random long-range impurity potential is discussed. It is shown that in the linear response regime a decisive role is played by the indirect backscattering mechanism via quasilocalized states at the Fermi level; this can provide much higher backscattering rate than any direct backscattering process. For the realistic contact lengths ($\leq 2000$nm) the scattering processes prove to be independent, in spite of coherence of the electron wave. The distribution function of conductance fluctuations is obtained by direct numerical calculations as well as estimated within an analytical model for the first time. It is shown to be a generalized Poisson distribution. Estimates are made for quantum point contact performance at different choice of parameters. In particular, it is the better the larger the intermode distance is compared to the amplitude of the random impurity potential.
Source: arXiv (Cornell University)
Institutions: Chalmers University of Technology, University of Gothenburg
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2952754711