Near Transform-Limited Quantum Dot Linewidths in a Broadband Photonic Crystal Waveguide

Planar nanophotonic structures enable broadband, near-unity coupling of emission from quantum dots embeddedwithin, thereby realizing ideal singe-photon sources. The efficiency and coherence of the single-photon source islimited by charge noise, which results in the broadening of the emission spectrum. We report suppression of the noiseby fabricating photonic crystal waveguides in a gallium arsenide membrane containing quantum dots embedded in ap-i-ndiode. Local electrical contacts in the vicinity of the waveguides minimize the leakage current and allow fastelectrical control (≈4 MHz bandwidth) of the quantum dot resonances. Resonant linewidth measurements of 79 quan-tum dots coupled to the photonic crystal waveguides exhibit near transform-limited emission over a 6 nm wide range ofemission wavelengths. Importantly, the local electrical contacts allow independent tuning of multiple quantum dots onthe same chip, which together with the transform-limited emission are key components in realizing multiemitter-basedquantum information processing.