Ultrahigh-Purity Single-Photon Emission from 2D WSe2 via Effective Suppression of Classical Emission

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Abstract
Single-photon emitters (SPEs) in two-dimensional WSe2 offer high extraction efficiency and on-chip compatibility, but achieving high purity remains challenging. We present two strategies to suppress classical emission and enhance purity in WSe2-based SPEs. In monolayer WSe2, we exploited the presence and absence of valley-spin locking in free and bound excitons, respectively, to achieve purity of 98.3% via polarization control and 99.0% combined with near-resonant excitation. In bilayer WSe2, we obtained 97.0% purity without polarization filtering, enabled by the indirect band gap and inversion symmetry. These values represent some of the highest as-measured purities reported for 2D TMD SPEs. Our methods do not require complex fabrication or instrumentation and are supported by first-principles calculations of the vacancy state of Se and spin degeneracy. This work offers practical pathways for realizing high-quality single-photon sources for emerging quantum technologies.
Funding Information
  • Welch Foundation (C-1509, C-2144)
  • Air Force Office of Scientific Research (FA9550-22-1-0408)
  • Alfred P. Sloan Foundation
  • W. M. Keck Foundation
  • Division of Electrical, Communications and Cyber Systems (1943895, 2235276, 2246564)
  • Division of Civil, Mechanical and Manufacturing Innovation (1538127)
  • Division of Materials Research (1753054, 2103842, 2326628, 2443684)

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