Quantum efficiency of the B-center in hexagonal boron nitride

Area of Science:

• Quantum photonics
• Materials science
• Solid-state physics

Background:

• B-centers in hexagonal boron nitride (hBN) are promising quantum emitters due to precise positioning and reproducible wavelengths (~436 nm).
• Their application in quantum photonics is hindered by the need for precise quantum efficiency (QE) quantification.

Purpose of the Study:

• To directly measure the quantum efficiency (QE) of single B-centers in thin hexagonal boron nitride (hBN) flakes.
• To propose methods for quantifying the QE of B-centers in thicker hBN flakes.
• To assess the potential of B-centers for quantum photonics applications.

Main Methods:

• Engineered B-centers in a 35 nm hBN flake using electron beam irradiation.
• Altered the local dielectric environment by transferring a 250 nm hBN flake on top of the emitter-containing flake.
• Measured changes in photoluminescence lifetimes to determine QE.

Main Results:

• Determined the QE of B-centers in the thin hBN flake.
• B-centers in thin flakes achieved QE exceeding 40%.
• Showed that near-unity QEs are achievable in thick hBN flakes with Purcell enhancement.

Conclusions:

• B-centers in thin hBN flakes exhibit significant quantum efficiency.
• Proposed methods enable QE quantification in thicker hBN flakes.
• B-centers hold substantial promise for future quantum photonics applications.