Violet to Near-Infrared Optical Addressing of Spin Pairs in Hexagonal Boron Nitride

Optically addressable solid-state spins are an important platform for practical quantum technologies. Van der Waals material hexagonal boron nitride (hBN) is a promising host as it contains a wide variety of optical emitters, but thus far observations of addressable spins have been sparse, and most of them lacked a demonstration of coherent spin control. Here, robust optical readout of spin pairs in hBN is demonstrated with emission wavelengths spanning from violet to the near-infrared. It is found that these broadband spin pairs exist naturally in a variety of hBN samples from bulk crystals to powders to epitaxial films, and can be coherently controlled across the entire wavelength range. Furthermore, the optimal wavelengths are identified for independent readout of spin pairs and boron vacancy spin defects co-existing in the same sample. These results establish the ubiquity of the optically addressable spin pair system in hBN across a broad parameter space, making it a versatile playground for spin-based quantum technologies.