Non-resonant dot–cavity coupling and its potential for resonant single-quantum-dot spectroscopy

Abstract

Non-resonant emitter–cavity coupling is a fascinating effect recently observed as unexpected pronounced cavity resonance emission even in strongly detuned single quantum dot–microcavity systems1,2,3. This phenomenon indicates strong, complex light–matter interactions in these solid-state systems, and has major implications for single-photon sources4,5,6 and quantum information applications1,2,3,7,9. We study non-resonant dot–cavity coupling of individual quantum dots in micropillars under resonant excitation, revealing a pronounced effect over positive and negative quantum dot mode detunings. Our results suggest a dominant role of phonon-mediated dephasing in dot–cavity coupling, giving a new perspective to the controversial discussions ongoing in the literature. Such enhanced insight is essential for various cavity-based quantum electrodynamic systems using emitters that experience phonon coupling, such as colour centres in diamond10 and colloidal nanocrystals11. Non-resonant coupling is demonstrated to be a versatile ‘monitoring’ tool for observing relevant quantum dot s-shell emission properties and background-free photon statistics.