Triggered emission of indistinguishable photons from an organic dye molecule

Abstract

Single molecules in solid state matrices have been proposed as sources of single photon Fock states back 20 years ago. Their success in quantum optics and in many other research fields stems from the simple recipes used in the preparation of samples, with hundreds of nominally identical and isolated molecules. Main challenges as of today for their application in photonic quantum technologies are the optimization of light extraction and the on-demand emission of indistinguishable photons. We here present Hong–Ou–Mandel (HOM) experiments with photons emitted by a single molecule of dibenzoterrylene in an anthracene nanocrystal at 3 K, under continuous wave and also pulsed excitation. A detailed theoretical model is applied, which relies on independent measurements for most experimental parameters, hence allowing for an analysis of the different contributions to the two-photon interference visibility, from residual dephasing to spectral filtering. A HOM interference visibility of more than 75% is reported, which, according to the model, is limited by the residual dephasing present at the operating temperature.

Solid‐State Single‐Photon Sources: Recent Advances for Novel Quantum Materials

“…This review will not cover the state-of-the-art of these systems in depth, but we mention that molecule-based singlephoton sources (a complete review on the topic can be consulted in Ref. [133]) have shown competent degree of photon indistinguishability emitted from a single source, [134,135] between two remote sources [136,137] and even the coupling between two molecules allowing to tune the sub-and superradiant nature of the emission. [138] Experiments on molecule-emitters have also demonstrated the energy-tuning of the single photon emission via strain [139] and testbed quantum key distribution schemes with molecule sources at room temperature.…”

Efficient room-temperature molecular single-photon sources for quantum key distribution

“…They show bright single-photon emission of high purity even at room temperature [23,24,25,26] and excellent photostability in long-term measurements [27]. At cryogenic temperature, PAH molecules emit highly indistinguishable photons [20,28], enabling more complex quantum communication protocols [29] or linear optic processing [30]. Molecular quantum emitters are suitable for the integration in hybrid photonic structures too, allowing for an almost 100% collection efficiency [31,32].…”

Future Paths in Cryogenic Single-Molecule Fluorescence Spectroscopy

“…In many ways, single bright and photostable fluorescent molecules at a cryogenic temperature behave as ideal individual two-level systems and are excellent single-photon sources for integrated quantum photonics . Cryogenic single-molecule fluorescence spectroscopy has strongly focused on quantum-optical applications and single-photon interactions, notably those requiring coherent interaction and indistinguishable photons. − The photons emitted on the lifetime-limited ZPL of a single fluorescent molecule are indistinguishable and can be spectrally tuned by external perturbations such as electric field, elastic deformations, , and optically induced perturbations . Photons hardly interact with one another, which makes them attractive carriers to transmit quantum information.…”