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

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 systems(1-3). This phenomenon indicates strong, complex light-matter interactions in these solid-state systems, and has major implications for single-photon sources(4-6) and quantum information applications(1-3,7,9). 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 diamond(10) and colloidal nanocrystals(11). 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.