We measured the second-order correlation function of the cathodoluminescence intensity and investigated the Purcell effect by comparing the lifetimes of quantum emitters with and without metal structure. The increase in the electromagnetic local density of state due to the coupling of a quantum emitter with a plasmonic structure causes a shortening of the emitter lifetime. Since the plasmon-enhanced electric field is confined well below the wavelength of light, the quantum emitter lifetime is changed in the nanoscale range. In this study, we combined cathodoluminescence in scanning (transmission) electron microscopy with Hanbury Brown--Twiss interferometry to measure the Purcell effect with nanometer and nanosecond resolutions. We used nitrogen-vacancy centers contained in nanodiamonds as the emitters and compared their lifetime in different environments: on a thin
SiO2 membrane, on a thick flat silver film, and embedded in a silver film. The lifetime reductions of nitrogen-vacancy centers were observed in the samples with silver. We evaluated the lifetime by analytical calculation and numerical simulations and revealed the Purcell effects of emitters coupled to the propagating and localized surface plasmons.
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 (
NV0) centers excited by a converged electron beam in an aberration-corrected scanning transmission electron microscope. Plasmon-mediated
NV0 cathodoluminescence exhibits a 16-fold increase in luminescence intensity correlated with a threefold reduction in photon bunching compared with that of uncoupled
NV0 centers. This effect is ascribed to the excitation of single temporally uncorrelated
NV0 centers by single surface plasmon polaritons. Spectrally resolved Hanbury Brown--Twiss interferometry is employed to demonstrate that the bunching is mediated by the
NV0 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
NV0 luminescence.
Engineering the photo-emission characteristics of single-photon emitters is crucial for the growing field of quantum technologies. We show that the photoluminescence of a single nitrogen-vacancy color center in nanodiamond could be significantly enhanced when attached to a gold film of 50 nm with preserving photophysical properties as a single photon source. The nitrogen-vacancy center on the gold film showed a decreased excited-state lifetime and a modified saturation characteristic. The photoluminescence enhancement was due to the enhanced electric field by the surface plasmon and the energy transfer from the excited state of nitrogen-vacancy centers to the surface plasmon.