Ballistic electronic transport in quantum cables

Ballistic spin transport without net charge transport in quantum wells

We demonstrate the ballistic transport of electron spin in the absence of net transport of electron charge. Spin-up electrons move in one direction, while an equal number of spin-down electrons move with the same velocities in the opposite direction, yielding no net charge motion. This effect, also referred to as a ‘pure’ spin current, results from the quantum mechanical interference of the tra...

Quantum transport through ballistic cavities: soft vs hard quantum chaos

We study transport through a two-dimensional billiard attached to two infinite leads by numerically calculating the Landauer conductance and the Wigner time delay. In the generic case of a mixed phase space we find a power-law distribution of resonance widths and a power-law dependence of conductance increments apparently reflecting the classical dwell time exponent, in striking difference to t...

Ballistic electron transport in stubbed quantum waveguides: experiment and theory

We present results of experimental and theoretical investigations of electron transport through stub-shaped waveguides or electron stub tuners (ESTs) in the ballistic regime. Measurements of the conductance G as a function of voltages, applied to different gates Vi (i =bottom, top, and side) of the device, show oscillations in the region of the first quantized plateau which we attribute to refl...

Transport through evanescent waves in ballistic graphene quantum dots

Crossover from Diffusive to Ballistic Transport in Periodic Quantum Maps

We derive an expression for the mean square displacement of a particle whose motion is governed by a uniform, periodic, quantum multi-baker map. The expression is a function of both time, t, and Planck’s constant, ~, and allows a study of both the long time, t → ∞, and semi-classical, ~ → 0, limits taken in either order. We evaluate the expression using random matrix theory as well as numerical...