Cavity Quantum Electrodynamics with Single Perovskite Quantum Dots: Assessing Rabi Coupling Strength, Pure Dephasing, and Spectral Diffusion

Precise characterization of emitter–cavity metrics is required for developing novel cavity quantum electrodynamics platforms. For single solid-state quantum emitters, the Rabi coupling strength ( g ) and the homogeneous line width are the most challenging, the latter being often blurred by spectral diffusion. Recently, perovskite quantum dots emerged as promising quantum emitters, motivating their integration into photonic structures. We demonstrate the deterministic and reversible coupling of individual CsPbBr 3 perovskite quantum dots to a tunable, high-quality factor, low mode volume open fibered microcavity at 10 K. Spatial and spectral tuning yields up to a 2-fold increase in single photon emission rate by the Purcell effect. Cavity tunability further enables the study of the spectral reshaping upon increasing the electromagnetic confinement. Combining temporal and spectral analyses allows us to assess g (up to 40 μeV) and to delineate the contributions of spectral diffusion and pure dephasing, paving the way for optimized cavity-coupled perovskite quantum dots.