Colossal photon bunching in quasiparticle-mediated nanodiamond cathodoluminescence

Abstract

Nanoscale control over the second-order photon correlation function ${g}^{(2)}(\ensuremath{\tau})$ is critical to emerging research in nonlinear nanophotonics and integrated quantum information science. Here we report on quasiparticle control of photon bunching with ${g}^{(2)}(0)>45$ in the cathodoluminescence of nanodiamond nitrogen vacancy (${\mathrm{NV}}^{0}$) centers excited by a converged electron beam in an aberration-corrected scanning transmission electron microscope. Plasmon-mediated ${\mathrm{NV}}^{0}$ cathodoluminescence exhibits a 16-fold increase in luminescence intensity correlated with a threefold reduction in photon bunching compared with that of uncoupled ${\mathrm{NV}}^{0}$ centers. This effect is ascribed to the excitation of single temporally uncorrelated ${\mathrm{NV}}^{0}$ centers by single surface plasmon polaritons. Spectrally resolved Hanbury Brown--Twiss interferometry is employed to demonstrate that the bunching is mediated by the ${\mathrm{NV}}^{0}$ phonon sidebands, while no observable bunching is detected at the zero-phonon line. The data are consistent with fast phonon-mediated recombination dynamics, a conclusion substantiated by agreement between Bayesian regression and Monte Carlo models of superthermal ${\mathrm{NV}}^{0}$ luminescence.