Dresden 2020 – wissenschaftliches Programm
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PLV VI: Plenarvortrag
Dienstag, 17. März 2020, 16:00–18:00, HSZ 01
Rydberg Excitons in Cuprous Oxide — •Manfred Bayer — Experimentelle Physik 2, TU Dortmund, D-44227 Dortmund, Germany
Excitons determine the optical properties of semiconductors and recently have attracted strong renewed interest because of novel materials with exciton binding energies exceeding by far the thermal energy at ambient conditions. Excitons were demonstrated first in cuprous oxide with a binding energy of about 90 meV, showing also that the hydrogen model provides a reasonable description of the exciton series. In 2014, high-resolution laser spectroscopy combined with high crystal quality allowed the observation of the hydrogen-like series up to the principal quantum number n=25 in cuprous oxide, corresponding to huge wave function exciton extensions in the micrometer range. This demonstration has formed the basis for taking unprecedented insights into exciton physics, for which several examples will be given: (a) Applying a magnetic field not only gives concise understanding of the exciton levels, but also allows to enter the regime of quantum chaos with surprising features like breakdown of all anti-unitary symmetries. (b) Similar to Rydberg atoms, the huge exciton size leads to giant interaction effects such as the Rydberg blockade, where injection of a single Rydberg exciton blocks the resonant excitation of another Rydberg exciton in a micrometer-sized surrounding. Recent studies suggest that the underlying interaction is of Van der Waals-type. This demonstration could lead to implementations of quantum technologies in an application-friendly, engineerable semiconductor environment.