Colloquium: Optical Signatures of Single-Photon Sources in Hexagonal Boron Nitride

Date: April 28, 2017
Time: 3:00 pm – 4:15 pm

Location: Exploratory Hall L003 (Google map)

Featured Speaker:
Annemarie Exarhos
University of Pennsylvania

Defect engineering in solid-state materials is a rapidly progressing field with applications in quantum information science, nanophotonics, and nanoscale sensing in biology and chemistry. Inspired by the success of the nitrogen-vacancy center in diamond as a single-photon source with room-temperature quantum coherence, recent efforts have uncovered analogous systems in other bulk wide-bandgap semiconductors such as silicon carbide and zinc oxide. In low-dimensional materials, however, defects with stable, highly localized, optically addressable electronic states can provide additional unique functionalities due to intrinsic spatial confinement and the ability to create multi-functional layered materials. Within the class of van der Waals materials, hexagonal boron nitride (h-BN) is rapidly emerging as an exciting system for solid-state quantum engineering in 2D as its large bandgap enables it to host single-photon sources exhibiting visible fluorescence.

Despite a recent surge of attention regarding h-BN's defects, much still remains to be understood, including the specific physical and electronic structure of h-BN’s quantum emitters and the influence of environmental perturbations such as different substrates, chemical treatments, and external applied fields. I will discuss our work on defect creation and the optical characterization of single-photon sources in h-BN as we attempt to answer these questions and understand the physics behind defect fluorescence in this material. Our studies of the defects' spectral, temporal, and spatial emission properties reveal a rich phenomenology of this new class of quantum emitters, with evidence for multilevel electronic structures, metastable states, photoswitching, and complex chemistries.

Refreshments will be served.