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We characterize the linear and nonlinear electron transport in quantum point contacts (QPCs) realized by a hybrid combination of etching and gating. We demonstrate that the strong electron confinement generated through this hybrid QPC process results in quantized subbands with a large energy separation, leading to the observation of robust one-dimensional quantum-transport effects. Measurements of the nonlinear differential conductance reveal an unexpected bunching of curves at 0.20-0.25×2e2/h, rather than at the expected value of 0.5×2e2/h. Application of a simple analytical model indicates that this bunching is associated with the highly asymmetric manner in which the source-drain voltage is dropped across the QPC near pinch-off and under nonequilibrium conditions. [ABSTRACT FROM AUTHOR]

Presents information discussing the space charge limited ballistic electron transport through double quantum well segments. Simulation of three different structures; How the anode currents in the structures oscillate; Increasing of the space charge.

The authors show that both real and imaginary parts of the admittance of short (ballistic or quasiballistic) semiconductor structures are oscillatory functions of the frequency with the period determined by the inverse electron transit time with the Fermi velocity. This oscillatory dependence is caused by the phase difference between the electrons injected from the opposite contacts. [ABSTRACT FROM AUTHOR]

We study ballistic electron transport through a finite chain of quantum circular rings in the presence of spin–orbit interaction of strength α. For a single ring, the transmission and reflection coefficients are obtained analytically and from them the conductance for a chain of rings as a function of α and of the wave vector k of the incident electron. We show that due to destructive spin interferences, the chain can be totally opaque for certain ranges of k, the width of which depends on the value of α. A periodic modulation of the strength α or of the ring radius widens the gaps considerably and produces a nearly binary conductance output. [ABSTRACT FROM AUTHOR]

Recent experimental studies of ballistic electron transport have pushed the transit time well into the subpicosecond dynamical regime. By applying the quantum dynamical theory to study ultrafast transient transport, we report results that are dramatically different from those predicted by the classical Boltzmann theory. [ABSTRACT FROM AUTHOR]

Examines the switching properties of a T-shaped quantum waveguide. Transient analysis of ballistic transport; Spectral contributions in the terahertz range; Accounts on the pronounced mixing effects; Sharing of electron wave function between the bound and metastables states of the initial and final eigenspectra.