Giant Rydberg Excitons in Cuprous Oxide

TL;DR

This paper reports the discovery of giant Rydberg excitons in cuprous oxide with large principal quantum numbers, revealing strong interactions and potential for quantum manipulation in solid-state systems.

Contribution

It demonstrates the existence of high-n Rydberg excitons in Cu2O with wave functions over 2 micrometers, showing strong dipole-dipole interactions and blockade effects.

Findings

Existence of Rydberg excitons up to n=25 in Cu2O

Giant wave function extensions over 2 micrometers

Observation of exciton blockade effect

Abstract

Highly excited atoms with an electron moved into a level with large principal quantum number are fascinating hydrogen-like objects. The giant extension of these Rydberg atoms leads to huge interaction effects. Monitoring these interactions has provided novel insights into molecular and condensed matter physics problems on a single quantum level. Excitons, the fundamental optical excitations in semiconductors consisting of a negatively charged electron and a positively charged hole, are the condensed matter analogues of hydrogen. Highly excited excitons with extensions similar to Rydberg atoms are attractive because they may be placed and moved in a crystal with high precision using microscopic potential landscapes. Their interaction may allow formation of ordered exciton phases or sensing of elementary excitations in the surrounding, also on a quantum level. Here we demonstrate the existence of Rydberg excitons in cuprous oxide, Cu2O, with principal quantum numbers as large as n=25 . These states have giant wave function extensions of more than 2 micrometers, compared to about a nanometer for the ground state. The strong dipole-dipole interaction is evidenced by a blockade effect, where the presence of an exciton prevents excitation of a further exciton in its vicinity.