Dynamically tuned non-classical light emission from atomic defects in hexagonal boron nitride

Abstract

Luminescent defects in hexagonal boron nitride (h-BN) have recently emerged as a promising platform for non-classical light emission. On-chip solutions, however, require techniques for controllable in-situ manipulation of quantum light. Here, we demonstrate the dynamic spectral and temporal tuning of the optical emission from h-BN via moving acousto-mechanical modulation induced by stimulated phonons. When perturbed by the propagating acoustic phonon, the optically probed radiative h-BN defects are periodically strained and their sharp emission lines are modulated by the deformation potential coupling. This results in an acoustically driven spectral tuning within a 2.5-meV bandwidth. Our findings, supported by first-principles theoretical calculations, reveal exceptionally high elasto-optic coupling in h-BN of ~50 meV/%. Temporal control of the emitted photons is achieved by combining the acoustically mediated fine-spectral tuning with spectral detection filtering. This study opens the door to the use of sound for scalable integration of h-BN emitters in nanophotonic and quantum information technologies ; This work was supported in part by the collaborative project "Single-Photon Generation in 2D Crystals for Quantum Information" (MDM-2014-0377) funded by the Condensed Matter Physics Center (IFIMAC) as well as by the Spanish MINECO under contracts MAT2014-53119-C2-1-R, MAT2016-77608-C3-1-P and MAT2017-83722-R. S.L. is a recipient of the Ramón and Cajal Research Grant (RyC-2011-09528) funded by the Spanish MINECO. J.J.P.B. acknowledges financial support from Spanish MINECO through Grant FIS2016-80434-P, the Fundación Ramón Areces, the Comunidad Autónoma de Madrid through MAD2D-CM Program (S2013/MIT-3007) and the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. W.S.P. was funded by the CNPq Fellowship programme (Pós-doutorado júnior) under grant 405107/2017-0 and acknowledges the computer resources at FinisTerrae2 and the technical support provided by Barcelona Supercomputing Center (RES-FI-2018-2-0036). We thank Eduardo J.H. Lee (UAM) for his help in sample preparation