Quantum confined Rydberg excitons in Cu2O nanoparticles

Funding: UK EPSRC Grant No. EP/S014403/1 and The Royal Society RGS\R2\192174. K.O. acknowledges EPSRC for PhD studentship support through grant no. EP/L015110/1. S.K.R. acknowledges the Carnegie Trust for the Research Incentive Grant RIG009823.The quantum confinement of Rydberg excitons is an important step towards exploiting their large nonlinearities for quantum applications. We observe Rydberg excitons in natural nanoparticles of Cu2O. We resolve up to the principal quantum number n=12 in a bulk Cu2O crystal and up to n=6 in nanoparticles extracted from the same crystal. The exciton transitions in nanoparticles are broadened and their oscillator strengths decrease as ∝n−4 compared to those in the bulk (decreasing as ∝n−3). We explain our results by including the effect of quantum confinement of exciton states in the nanoparticles. Our results provide an understanding of the physics of Cu2O Rydberg excitons in confined dimensions.Peer reviewe