The tunneling of Gaussian wave packets has been investigated by numerically solving the one-dimensional Schrödinger equation. The shape of wave packets interacting with a square barrier has been monitored for various values of the barrier width, height and initial width of the wave packet. Compared to the case of free propagation, the maximum of a tunneled wave packet exhibits a shift, which ca...

At total filling factor νT = 1, interlayer phase coherence in quantum Hall bilayers can result in a tunneling anomaly resembling the Josephson effect in the presence of strong fluctuations. The most robust experimental signature of this effect is a strong enhancement of the tunneling conductance at small voltages. The height and width of the conductance peak depend strongly on the area and tunn...

We investigate the atomic-scale tunneling characteristics of bilayer graphene on silicon carbide using the scanning tunneling microscopy. The high-resolution tunneling spectroscopy reveals an unexpected negative differential resistance (NDR) at the Dirac energy, which spatially varies within the single unit cell of bilayer graphene. The origin of NDR is explained by two near-gap van Hove singul...

– We studied spin-polarized tunneling through a vacuum barrier using spinpolarized scanning tunneling microscopy on Co(0001). By varying the tip-to-sample distance in a controlled way, the tunneling magnetoresistance, i.e., the tunneling current asymmetry for parallel and antiparallel configuration of tip and sample magnetization, was measured as a function of the gap width. At large gap widths...

We consider fundamental problems on the understanding of the tunneling phenomena in the context of the multi-dimensional wave function. In this paper, we reconsider the quantum state after tunneling and extend our previous formalism to the case when the quantum state before tunneling is in a squeezed state. Through considering this problem, we reveal that the quantum decoherence plays a crucial...

Electron tunneling through self-assembled monolayers of alkanethiols is investigated. Temperature-dependent current– voltage measurements are performed to distinguish between di erent conduction mechanisms. Temperature-independent electron transport is observed, proving direct tunneling as the dominant conduction mechanism of alkanethiols. An exponential dependence of tunneling current on molec...

The energy levels of CdSe quantum dots are studied by scanning tunneling spectroscopy. By varying the tip−dot distance, we switch from “shell-filling” spectroscopy (where electrons accumulate in the dot and experience mutual repulsion) to “shell-tunneling” spectroscopy (where electrons tunnel, one at a time, through the dot). Shell-tunneling spectroscopy provides the single-particle energy leve...

We measure electron tunneling in transistors made from C(140), a molecule with a mass-spring-mass geometry chosen as a model system to study electron-vibration coupling. We observe vibration-assisted tunneling at an energy corresponding to the stretching mode of C(140). Molecular modeling provides explanations for why this mode couples more strongly to electron tunneling than to the other inter...

The exact semiclassical wave function for a tunneling electron, coupled to the degrees of freedom of the host medium, is constructed. In our derivation the tunneling path is divided into an infinite set of infinitezimal segments and the decaying solutions of the stationary Shrödinger equations are matched for each neighboring segment from the beginning to the end of the tunneling path. This sol...