Speaker
Dr
Gilmar Eugenio Marques
(Universidad Federal de Sao Carlos, Sao Paolo, Brasil)
Description
In classical Physics, the motion of an electrically charged particle is only affected by the presence of a magnetic field if the particle enters a region of space in which the field is present. Meanwhile, in quantum Physics, a charged carrier can be affected by the electromagnetic vector potential even in regions where the magnetic field is not present.
This surprising contrast between classical and quantum Physics has been experimentally proven in several beautiful experiments in semiconducting, metallic and superconducting material systems, and has been named Aharonov-Bohm effect. More recently, however, several theoretical works have discussed the plausible existence of this effect even for neutral particles! In this talk will be shown the first clear experimental observation of the Aharonov-Bohm effect in neutral excitons formed in InAs quantum rings. Signatures of this effect appear as oscillations in the intensity of the photoluminescence emission bands with increasing magnetic fields and also depending on the dimensions of the quantum rings.
These oscillations are affected by the uniaxial strain field due to the piezoelectricity of the asymmetric InAs rings, as revealed by the atomic force microscopy, transmission electron microscopy images and X-Ray Diffraction measurements using synchrotron light. A simple theoretical model that describes the behavior of the excitonic interference pattern and its modulation with temperature and uniaxial electric fields has been used for the interpretation of the experimental data. The detection of Aharonov-Bohm oscillations mediated by electron-hole pair correlation is a fundamental quantum mechanical effect that will trigger further studies in this area of fundamental physics as well as technological applications.
