Magneto-conductance fingerprints of purely quantum states in the open quantum dot limit

Abstract

We present quantum magneto-conductance simulations, at the quantum low energy condition, to study the open quantum dot limit. The longitudinal conductance G(E,B) of spinless and non-interacting electrons is mapped as a function of the magnetic field B and the energy E of the electrons. The quantum dot linked to the semi-infinite leads is tuned by quantum point contacts of variable width w. We analyze the transition from a quantum wire to an open quantum dot and then to an effective closed system. The transition, as a function of w, occurs in the following sequence: evolution of quasi-Landau levels to Fano resonances and quasi-bound states between the quasi-Landau levels, followed by the formation of crossings that evolve to anti-crossings inside the quasi-Landau level region. After that, Fano resonances are created between the quasi-Landau states with the final generation of resonant tunneling peaks. By comparing the G(E,B) maps, we identify the closed and open-like limits of the system as a function of the applied magnetic field. These results were used to build quantum openness diagrams G(w,B). Also, these maps allow us to determine the w-limit value from which we can qualitatively relate the closed system properties to the open one. The above analysis can be used to identify single spinless particle effects in experimental measurements of the open quantum dot limit.

Exclusive sub-lattices for extended and localized states in graphene ribbons: their role in Klein tunneling, disorder and magnetic field effects

“…Also, this pattern is analogous to the one found in a conductance map (as a function of B and E) of a 2DEG quantum box. In a 2DEG quantum box the magnetic field B plays the same role of the quantity V/t considered in this work [47]. The pattern observed in the Fano resonances of figure 6 for B=8T arises from the Figure 5.…”

Optimization of the polarized Klein tunneling currents in a sub-lattice: pseudo-spin filters and latticetronics in graphene ribbons

“…where the self-energies R and L of the contact leads are numerically calculated using the recursive Green function method [27,37,38]. The polarization P of the sub-lattice (A or B, also called pseudo-spin) is calculated according to…”

Recovery of the scattering symmetry looking at the conductance in asymmetric graphene nano-ribbons systems using pseudo-spin filters

“…where E is the energy of the incoming electrons, the selfenergies [34] Σ R (right) and Σ L (left) of the contact leads are numerically calculated using the recursive Green function method [24,25,35], and H defines a central region that does not consider the contact leads Hamiltonians, H R and H L (all assembled via equation ( 1)). Using the above definitions we can write…”

“…For example, in an GaAs heterostructure the resonant tunneling only occurs for specific energies when two potential barriers are applied. For the rest of the energy spectrum the transmission is totally reduced in comparison with the case without barrier [23][24][25]. As far as we know, an enhancement of the transmission through the system due to the application of potential barriers was never reported.…”