Quantum Emission From Hexagonal Boron Nitride Monolayers

Atomically thin van der Waals crystals have recently enabled new scientific and technological breakthroughs across a variety of disciplines in materials science, nanophotonics and physics. However, non-classical photon emission from these materials has not been achieved to date. Here we report room temperature quantum emission from hexagonal boron nitride nanoflakes. The single photon emitter exhibits a combination of superb quantum optical properties at room temperature that include the highest brightness reported in the visible part of the spectrum, narrow line width, absolute photo-stability, a short excited state lifetime and a high quantum efficiency. Density functional theory modeling suggests that the emitter is the antisite nitrogen vacancy defect that is present in single and multi-layer hexagonal boron nitride. Our results constitute the unprecedented potential of van der Waals crystals for nanophotonics, optoelectronics and quantum information processing

Effect of charging on CdSe/CdS dot-in-rods single-photon emission

The photon statistics of CdSe/CdS dot-in-rods nanocrystals is studied with a method involving post-selection of the photon detection events based on the photoluminescence count rate. We show that flickering between two states needs to be taken into account to interpret the single-photon emission properties. With post-selection we are able to identify two emitting states: the exciton and the charged exciton (trion), characterized by different lifetimes and different second order correlation functions. Measurements of the second order autocorrelation function at zero delay with post- selection shows a degradation of the single photon emission for CdSe/CdS dot-in-rods in a charged state that we explain by deriving the neutral and charged biexciton quantum yields.Comment: 10 pages, 5 figure

Libertà va postando …. Sul blog di Vanini

EnThe debate on the relationship between human freedom and (religious or scientific) determinism finds its place, in this article, in a forum closer to young sensitivity: the blog, managed by Vanini for this purpose. Answering the questions of a student, the criticisms of a theologian and the statements of a philosopher, Vanini reaffirms the firm points of his thought.ItIl dibattito sul rapporto tra la libertà umana e il determinismo (religioso o scientifico) trova ospitalità, in questo articolo, in una sede prossima alla sensibilità giovanile: il blog, nell'occasione gestito da Vanini. Rispondendo alle domande di una studentessa, alle critiche di un teologo e alle affermazioni di un filosofo, Vanini ribadisce i punti fermi del suo pensiero