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Quantum ring mapping

Quantum ring mapping

Objective

Our project aims at observing the spatial modulations of local electron probability density along a quantum ring fabricated from a two-dimensional electron gas (2DEG) formed in an InGaAs heterostructure. As a magnetic field is applied perpendicular to the plane of such a ring, a periodic pattern of maxima and minima of electron probability density is predicted to appear, due to interferences of electron partial waves inside the ring (these interferences give rise to the well-known Aharonov-Bohm effect, causing periodic oscillations in the ring magneto resistance). In order to observe this phenomenon, we plan to use a low temperature (4.2K) atomic force microscope (AFM) in non-contact mode. A voltage bias will be applied on the tip of the AFM in order to create a local perturbation in the 2DEG underneath.

The principle is to record the changes of conductance of the quantum ring as a function of the tip position (i.e. the perturbation position) over the quantum ring, which will produce images related to the changes of electron probability density (the technique was demonstrated for quantum point contacts in M.A. Topinka et al., Science 289, 2323 (2000)). Using voltages applied on lateral (in-plane) gates patterned close to the quantum ring, we will investigate t he influence of the coupling of the ring to external electron reservoirs as well as the influence of the asymmetry of the ring. The biased scanning tip will also be used as a static scattered on one arm of the ring, and the influence of the position of the tip on Aharonov-Bohm oscillations will be characterized. Potential outcomes of this project are in the field of experimental quantum physics, quantum computation and electron optics.

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Coordinator

UNIVERSITE JOSEPH FOURIER GRENOBLE 1

Address

621 Avenue Centrale Domaine Universitaire
Grenoble

France

Administrative Contact

Serge HUANT (Dr)

Project information

Grant agreement ID: 515239

  • Start date

    1 May 2005

  • End date

    31 August 2006

Funded under:

FP6-MOBILITY

Coordinated by:

UNIVERSITE JOSEPH FOURIER GRENOBLE 1

France