Backscattering off a point impurity: Current enhancement and conductance greater thane2/hper channel

Conductance quantization and backscattering.

The transmission behavior of a quantum point contact in a magnetic field is calculated, exhibiting in detail the influence of intersubband scattering. In contrast to the commonly known reduction of backscattering by a magnetic field, it is shown here that a weak field can cause increased backscattering. Nevertheless, the present results serve to illustrate that backscattering can occur without ...

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

It is known that the conductance of a quantum point contact is quantized in units of 2e2/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 qu...

Conductance enhancement in quantum-point-contact semiconductor-superconductor devices

We present numerical calculations of the conductance of an interface between a phase-coherent twodimensional electron gas and a superconductor with a quantum point contact in the normal region. Using a scattering matrix approach we reconsider the geometry of De Raedt, Michielsen, and Klapwijk @Phys. Rev. B 50, 631 ~1994!# which was studied within the time-dependent Bogoliubov–de Gennes formalis...

Soft Disorder Effects in the Conductance Quantization in Quantum Point Contacts: Indirect Backscattering Statistics

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 r...

From Integrability To Conductance, Impurity Systems