Tunnelling transmission resonances through a zero-dimensional structure

2010

Phys. Rev. B

We propose numerical simulations of longitudinal magnetoconductance through a finite antidot lattice located inside an open quantum dot with a magnetic field applied perpendicular to the plane. The system is connected to reservoirs using quantum point contacts. We discuss the relationship between the longitudinal magnetoconductance and the generation of transversal couplings between the induced open quantum dots in the system. The system presents longitudinal magnetoconductance maps with crossovers ͑between transversal bands͒ and closings ͑longitudinal decoupling͒ of fundamental quantum states related to the open quantum dots induced by the antidot lattice. A relationship is observed between the distribution of antidots and the formed conductance bands, allowing a systematic follow up of the bands as a function of the applied magnetic field and quantum point-contact width. We observed a high conductance intensity ͓between n and ͑n +1͒ quantum of conductance, n =1,2,. . .͔ in the regions of crossover and closing of states. This suggests transversal couplings between the induced open quantum dots of the system that can be modulated by varying both the antidots potential and the quantum point-contact width. A new continuous channel ͑not expected͒ is induced by the variation in the contact width and generate Fano resonances in the conductance. These resonances can be manipulated by the applied magnetic field.

Section: Discussionmentioning

confidence: 99%

Fingerprints of transverse and longitudinal coupling between induced open quantum dots in the longitudinal magnetoconductance through antidot lattices

Ujevic

2010

Phys. Rev. B

“…5 Open quantum dots ͑OQDs͒ with highly transmitting channels are systems wherein the single-electron charging effects are not relevant and single-particle resonances should be robust with respect to electron-electron interactions. A example of this type of system is described experimentally by Lundberg et al 6 OQD structures with such characteristics are candidates for the wave function mapping based on shifts in energy of the resonances, induced by an atomic force microscope ͑AFM͒ tip. 7 Such a procedure could also be extended to imaging of quantum billiard states.…”

Section: Introductionmentioning

confidence: 99%

Imaging and switching of Fano resonances in open quantum cavities

Schulz

2005

Phys. Rev. B

We present a systematic numerical investigation of the imaging of states in highly transmiting open quantum dots within a Green's function method applied to a tight-binding lattice model. We show evidence that images obtained from conductance change are not bona fide images of the unperturbed probability densities, because the coupled quantum dot-tip system induces coupling between several resonances, hindering a reliable interpretation of the conductance maps. We suggest that mapping the energy shifts of the resonances may provide the necessary complementary tool for good wave function imaging in quantum billiards.

“…Open quantum dots (OQD) with highly transmitting channels are systems where single-particle resonances should be robust with respect to electron-electron interactions. An example of this type of system is described experimentally by Lundberg et al [3], OQDs with such characteristics are suitable for the wavefunction mapping of the quasi-bound states, based on shifts in energy of the resonances induced by AFM tip [4]. This procedure might be also useful for imaging of quantum billiard states [5].…”

Section: Introductionmentioning

confidence: 99%

Wave function mapping at Fano resonances and conductance switching in open quantum dots

Schulz

2005

phys. stat. sol. (c)

We numerically simulate the effects of a controllable impurity induced by an atomic microscope tip scanned on an open quantum dot with highly transmitting channels. The coupled quantum dot -tip system may result in a transistor like device, for which the conductance switching is a function of the position, spatial dimensions and potential of the perturbation induced by the tip. For realistic dimensions we show that energy shifts of the resonances deliver a bona fide imaging of low energy isolated quantum dot states, as well as of higher energy states coupled to the continuum (Fano resonances).