Tunable and Low-Noise WSe₂ Quantum Emitters for Quantum Photonics

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 (h-BN): encapsulation and electrostatic biasing. We demonstrate that h-BN encapsulation alone suppresses spectral wandering (from '-170 mu eV to '-40 mu eV) and narrows emission linewidths (from '-524 mu eV to '-120 mu eV), while applied bias enables stable Stark tuning over a 280 mu eV range and further linewidth narrowing down to '-100 mu eV, reaching the resolution-limited regime. Timeresolved and second-order correlation measurements confirm stable monoexponential 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_dec and total broadening OW = W_exp - W_dec-with both being reduced more than fivefold 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.