Athanasios Paralikis, Paweł Wyborski, Pietro Metuh, Niels Gregersen, Battulga Munkhbat
Low-noise and tunable single-photon sources are essential components of photonic quantum technologies. However, in WSe 2 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 μ eV to ∼ 40 μ eV ) and narrows emission linewidths (from ∼ 524 μ eV to ∼ 120 μ eV ), while applied bias enables stable Stark tuning over a 280 μ eV range and further linewidth narrowing down to ∼ 100 μ eV , reaching the resolution-limited regime. Time-resolved 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 Δ W = 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 WSe 2 quantum emitters, potentially realizing electrically controllable sources of indistinguishable single photons for future photonic quantum technologies.