Abstract
Low-noise and tunable single-photon sources are essential components of photonic quantum technologies. However, in WSe₂ quantum emitters, charge noise from fluctuations in their local electrostatic environment remains a major obstacle to achieving transform-limited single-photon emission and high photon indistinguishability. Here, we systematically investigate two noise mitigation strategies in hexagonal boron nitride (hBN) encapsulation and electrostatic biasing. We demonstrate that hBN encapsulation alone suppresses spectral wandering (from ∼170 μeV to ∼40 μeV) and narrows emission linewidths (from ∼500 μeV to ∼150 μeV), while applied bias enables stable Stark tuning over a 280 μeV range and further linewidth narrowing down to ∼100 μeV reaching the resolution-limited regime. Time-resolved and second-order correlation measurements confirm stable mono-exponential decay and high single-photon purity (g⁽²⁾(0) ≈ 0.01) with no observable blinking. To quantify progress toward the transform limit, we define two figures of merit: the linewidth ratio R = W_exp / W_rad and total broadening Δ W = W_exp - W_rad, with both being reduced more than five-fold in optimized devices. These results provide a robust framework for developing and evaluating low-noise, tunable WSe₂ quantum emitters, potentially realizing electrically controllable sources of indistinguishable single-photons for future photonic quantum technologies.