Temperature dependent temporal coherence of metallic-nanoparticle-induced single-photon emitters in a WSe<sub>2</sub> monolayer
Martin von Helversen, Lara Greten, Imad Limame, Ching‐Wen Shih, Paul Schlaugat, C. Antón, Christian Schneider, Bárbara L. T. Rosa, Andreas Knorr, Stephan Reitzenstein
Abstract
Abstract In recent years, much research has been undertaken to investigate the suitability of two-dimensional materials to act as single-photon sources with high optical and quantum optical quality. Amongst them, transition-metal dichalcogenides, especially WSe 2 , have been one of the subjects of intensive studies. Yet, their single-photon purity and photon indistinguishability remain the most significant challenges to compete with mature semiconducting systems such as self-assembled InGaAs quantum dots. In this work, we explore the emission properties of quantum emitters in a WSe 2 monolayer which are induced by metallic nanoparticles. Under quasi-resonant pulsed excitation, we verify clean single-photon emission with a g (2) (0) = 0.036 ± 0.004. Furthermore, we determine the temperature dependent coherence time via Michelson interferometry, where a value of (13.5 ± 1.0) ps is extracted for the zero-phonon line at 4 K, which reduces to (9 ± 2) ps at 8 K. Associated time-resolved photoluminescence experiments reveal a decrease of the decay time from (2.4 ± 0.1) ns to (0.42 ± 0.05) ns. This change in decay time is explained by a model which considers a Förster-type resonant energy transfer process which yields a strong temperature induced energy loss from the single-photon emitters to the nearby Ag nanoparticle.