Rydberg excitons in cuprous oxide : macroscopic quantum systems coupled to nanoplasmonic and nanophotonic components

Abstract

Excitons in cuprous oxide have large binding energies, which implies that different principal quantum number state excitons can be created as they are energetically not spaced too closely to each other nor to the ionization continuum. High principal quantum number Rydberg excitons in cuprous oxide are macroscopic quantum systems with spatial extensions in the several hundreds of nm up to several µm range. This implies, that excitation with a focused light beam leads to a large overlap of light and matter wavefunctions and should lead to an enhanced optical transition. In this thesis, we are going to show that the dipole selection rules in cuprous oxide Rydberg excitons can be manipulated via excitation with orbital angular momentum light or via the quadrupole field of plasmonic antennas. Both such light fields posses a strong field gradient or an additional angular momentum. This way, different angular momentum quantum number state excitons can be switched on and off, which is attractive for quantum state engineering. The mesoscopic size of cuprous oxide Rydberg excitons also implies that already µm-sized structures lead to mesoscopic quantum size effects. This can be advantageous for the realization of quantum technologies, such as optical switching applications, based on cuprous oxide Rydberg excitons.