A 3D Polymeric Platform for Photonic Quantum Technologies

Abstract

The successful development of future photonic quantum technologies will much depend on the possibility of realizing robust and scalable nanophotonic devices. These should include quantum emitters like on‐demand single‐photon sources and non‐linear elements, provided their transition linewidth is broadened only by spontaneous emission. However, conventional strategies to on‐chip integration, based on lithographic processes in semiconductors, are typically detrimental to the coherence properties of the emitter. Moreover, such approaches are difficult to scale and bear limitations in terms of geometries. Here an alternative platform is discussed, based on molecules that preserve near‐Fourier‐limited fluorescence even when embedded in polymeric photonic structures. 3D patterns are achieved via direct laser writing around selected molecular emitters, with a fast, inexpensive, and scalable fabrication process. By using an integrated polymeric design, detected photon counts of about 2.4 Mcps from a single cold molecule are reported. The proposed technology will allow for competitive organic quantum devices, including integrated multi‐photon interferometers, arrays of indistinguishable single‐photon sources, and hybrid electro‐optical nanophotonic chips.

Laser-Induced Frequency Tuning of Fourier-Limited Single-Molecule Emitters

“…Indeed, the effect is directly activated on the emitting sample with no need for additional nanofabrication steps (e.g., lithography or etching in order to define the electrodes), and, being confined to the confocal beam volume, it enables spatial resolution at the micron level. On the other side, once doped with singlemolecule concentration, homogeneously deposited on the substrate via drop-casting and desiccation, 27 or even integrated in nanophotonic structures, 15 DBT:Ac nanocrystals allow for spatial isolation of individual molecules, which can thus be selectively tuned by laser focusing. This is shown in Figure 3, where the ZPL peaks of five nearby molecules, each contained in a different nanocrystal (data of different color), are probed at regular time intervals while exposing only one of the molecules to 2 min long laser pulses with increasing power.…”

“…Single fluorescent molecules of polycyclic aromatic hydrocarbons (PAHs) embedded in crystalline organic matrices are widely considered highly coherent, stable, and bright two-level quantum systems in the solid state. − Indeed, they can be operated as single-photon sources, combining high count rate and Fourier-limited line widths, − or as nanoprobes with exquisite sensitivity to electric fields, pressure, and strain. , PAH-based quantum devices can also be readily integrated in photonic chips. − A major advantage of PAH systems resides in the possibility to mass produce nominally identical fluorescent molecules at low costs and still obtain outstanding optical and optoelectronic properties. PAHs are under investigation for their use also in organic solar cells, as well as in super-resolution microscopy methods .…”

Real-time two-photon interference from distinct molecules on the same chip

“…Molecular quantum emitters have already shown a great potential for integration in photonic circuits [25,[48][49][50][51][52][53]. In this paper we study the problem of TPI from distinct molecular emitters on chip, attaining and combining together the following milestones: simultaneously addressing on the same sample several single-molecules operating as on-demand single photon sources, tuning independently their relative zero-phonon line (ZPL) frequency, measuring in semi real-time two photon interference from such distinct sources and extracting information about joint properties of the photon pairs.…”

Indistinguishable photons on demand from an organic dye molecule

“…A photonic resonance can modify both the radiation pattern and the spectral distribution of the emission, in order to bring the source brightness to the state-of-the-art level [45]. In this respect, the same type of system has been shown to g (2) data g (2) fit g (2) data g (2) fit be particularly suitable for the integration in hybrid photonic structures [46,47].…”