Redistribution and g-Factor Tuning of Localized Excitons in Site-controlled Quantum Emitters by Reversible Strain Fields

Localized excitons in monolayer transition metal dichalcogenides (ML-TMDs) are attracting considerable interest for their capability to generate single photons with high brightness [1]. Since both spatial strain gradients[2] and defects play a crucial role in inducing single photon emission, achieving dynamic control of strain fields in 2D materials can thus allow us to engineer the quantum emitters’ properties and to exploit their full potential for quan-tum technologies. In this work, we show how strain fields provided by ordered arrays of piezoelectric micro-pillars can be used to both control the nucleation site of quantum emitters and dinamically modify their emission properties [3,4]. In particular, we demonstrate that the energy of lo-calized excitons in ML WSe2 can be precisely tuned across a spectral range as large as tens of meV with no change in the multi-photon emission probability [3]. We observed that the applied strain modifies in a reversible way the emitters’ distribution, thus allowing for a con-trollable tuning of their optical properties. We also provide a theoretical model based on the diffusion equations for the exciton in presence of strain fields that explains the experimental results we found[4]. Furthermore, we exploited deformation fields to fine tune the g-factor of the emitters, allowing for the investigation of their response in presence of magnetic field. Since ML-TMDs offer unique optical and electronical properties such as inversion sym-metry breaking, strong light-matter interaction, large spin-orbit coupling and valley selective optical selection rules, efficient TMDs-based single photon sources could open to novel possibilities in advanced quantum optics protocols. Our hybrid ML-TMDs-piezoelectric platform bursts into this context, providing a simple method to fabricate ordered arrays of single photon sources with tuneable energy.