The Influence of Electrostatic Lenses on Wave Packet Dynamics

The control of coherent electrons is becoming relevant in emerging devices as (semi-)ballistic transport is observed within nanometer semiconductor structures at room temperature. The evolution of a wave packet – representing an electron in a semiconductor – can be manipulated using specially shaped potential profiles with convex or concave features, similar to refractive lenses used in optics. Such electrostatic lenses offer the possibility, for instance, to concentrate a single wave packet which has been invoked by a laser pulse, or split it up into several wave packets. Moreover, the shape of the potential profile can be dynamically changed by an externally applied potential, depending on the desired behaviour. The evolution of a wave packet under the influence of a two-dimensional potential – the electrostatic lens – is investigated by computing the physical densities using the Wigner function. The latter is obtained by using the signed-particle Wigner Monte Carlo method.