Sub-to-super-Poissonian photon statistics in cathodoluminescence of color center ensembles in isolated diamond crystals

Abstract

Impurity-vacancy centers in diamond offer a new class of robust photon sources with versatile quantum properties. While individual color centers commonly act as single-photon sources, their ensembles have been theoretically predicted to have tunable photon-emission statistics. Importantly, the particular type of excitation affects the emission properties of a color center ensemble within a diamond crystal. While optical excitation favors non-synchronized excitation of color centers within an ensemble, electron-beam excitation can synchronize the emitters excitation and thereby provides a control of the second-order correlation function g 2(0). In this letter, we demonstrate experimentally that the photon stream from an ensemble of color centers can exhibit g 2(0) both above and below unity, thereby confirming long standing theoretical predictions by Meuret et al. [S. Meuret, L. H. G. Tizei, T. Cazimajou, et al., “Photon bunching in cathodoluminescence,” Phys. Rev. Lett., vol. 114, no. 19, p. 197401, 2015.]. Such a photon source based on an ensemble of few color centers in a diamond crystal provides a highly tunable platform for informational technologies operating at room temperature.

Cathodoluminescence Nanoscopy: State of the Art and Beyond

“…Nevertheless, the CL-measured g (2) (Δ t ) of multiple defect centers shows strong photon bunching (Figure b) in contrast to PL-measured g (2) (Δ t ). ,, This bunching behavior originates from the synchronized emission from multiple centers excited by the same electron through the cascade decay. More recently, an experimental demonstration of the crossover between the bunching and antibunching regimes was provided by varying the electron-beam current in the CL study of color centers in diamond crystals, confirming the tunability of photon-correlation statistics in CL predicted by Meuret et al Based on a developed statistical model that determines the bunching strength g (2) (0) from the electron beam current, emitter decay lifetime, and electron excitation efficiency, the precise measurements of photon bunching permit retrieving the information about lifetime and excitation/emission efficiency of emitters with a high spatial resolution. − For example, the nanoscale spatial distribution of excitation/emission efficiency for InGaN/GaN quantum wells is visualized by determining the CL-measured g (2) function in a spatially resolved manner as shown in Figure c. With advances in ultrafast microscopy, the photon correlation measurement with pulsed electron beams becomes another possible approach. , Furthermore, we note that a recent study presents a scheme to discriminate coherent and incoherent CL using photon correlation measurements, as well as quantifying their contributions to the detected signal, through measuring and fitting the specific bunching peak as the peak width is determined by the time scale of coherent and incoherent CL emission processes …”

“…34,135,136 This bunching behavior originates from the synchronized emission from multiple centers excited by the same electron through the cascade decay. More recently, an experimental demonstration of the crossover between the bunching and antibunching regimes was provided by varying the electron-beam current in the CL study of color centers in diamond crystals, 137 confirming the tunability of photon-correlation statistics in CL predicted by Meuret et al 135 Based on a developed statistical model that determines the bunching strength g (2) (0) from the electron beam current, emitter decay lifetime, and electron excitation efficiency, the precise measurements of photon bunching permit retrieving the information about lifetime and excitation/emission efficiency of emitters with a high spatial resolution. 138−140 For example, the nanoscale spatial distribution of excitation/emission efficiency for InGaN/GaN quantum wells is visualized by determining the CL-measured g (2) function in a spatially resolved manner as shown in Figure 5c.…”