Room-temperature phonon-coupled single-photon emission in hexagonal boron nitride

Photon-lattice (phonon) coupling is fundamental to light-matter interaction, particularly when it reaches the quantum limit of the phonon-coupled single-photon emission, which holds great potential for quantum manipulation and quantum information transduction. Here, we report single defect state-phonon coupling in hexagonal boron nitride (hBN) at room temperature. An ultrabroad spectrum of single-photon emissions can be achieved by selecting the excitation energies. Using photoluminescence excitation spectroscopy, we observe single-phonon-assisted resonance-enhanced single-photon emission, along with multiple phonon replicas that herald the creation of phonon Fock state. We also develop a transition model to gain insight into the physical process behind the single defect state-phonon coupling. Our work sets the stage for manipulating electron-phonon coupling state with single quantum-level precision at room temperature.