Abstract
Controlling and manipulating individual quantum systems in solids underpins the growing interest in the development of scalable quantum technologies. Recently, hexagonal boron nitride (hBN) has garnered significant attention in quantum photonic applications due to its ability to host optically stable quantum emitters. However, the large bandgap of hBN and the lack of efficient doping inhibits electrical triggering and limits opportunities to study the electrical control of emitters. Here, we show an approach to electrically modulate quantum emitters in an hBN-graphene van der Waals heterostructure. We show that quantum emitters in hBN can be reversibly activated and modulated by applying a bias across the device. Notably, a significant number of quantum emitters are intrinsically dark and become optically active at non-zero voltages. To explain the results, we provide a heuristic electrostatic model of this unique behavior. Finally, employing these devices we demonstrate a nearly-coherent source with linewidths of ~160 MHz. Our results enhance the potential of hBN for tunable solid-state quantum emitters for the growing field of quantum information science.