On-demand reversible switching of the emission mode of individual semiconductor quantum emitters using plasmonic metasurfaces

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications as quantum information, quantum communication and quantum cybersecurity. The central building block for these applications is a quantum emitter (QE), a controllable source of single photons or photon pairs. Semiconductor QEs such as perovskite nanocrystals (PNCs) and semiconductor quantum dots (QDs) have been demonstrated to be a promising material for pure single-photon emission, and their hybrids with plasmonic nanocavities may serve as sources of photon pairs. Here we have designed a system in which individual quantum emitters and their ensembles can be traced before, during, and after the interaction with the external plasmonic metasurface in controllable way. Upon coupling the external plasmonic metasurface to the array of QEs, the individual QEs switch from single-photon to photon-pair emission mode. Remarkably, this method does not affect the chemical structure and composition of the QEs, allowing them to return to their initial state after decoupling from the plasmonic metasurface. By employing this approach, we have successfully demonstrated the reversible switching of the ensemble of individual semiconductor QEs between single-photon and photon pair emission modes. This significantly broadens the potential applications of semiconductor QEs in quantum technologies

Metal–Polymer Heterojunction in Colloidal-Phase Plasmonic Catalysis

[EN] Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD+ to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal-polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD+ reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity.This work was supported by grant PID2019-111772RB-I00 funded by MCIN/AEI/10.13039/501100011033 and grant IT 1254-19 funded by Basque Government. The authors acknowl- edge the financial support of the European Commission (EUSMI, Grant 731019). S.B. is grateful to the European Research Council (ERC-CoG-2019 815128). The authors acknowledge the contributions by Dr. Adrian Pedrazo Tardajos related to sample support and electron microscopy experiments

Hybrid system based on gold bipyramids and water-soluble conjugated polymers for thermoplasmonic applications

Resumen del póster presentado a la XXXVIII Reunión Bienal de la Real Sociedad Española de Química, celebrada en el Palacio de Congresos de Granada, del 27 de junio al 30 de junio de 2022.Upon illumination at the surface plasmon resonance, electron density of metallic nanoparticles oscillates at the frequency of incoming light. The decay of the plasmon band leads to heat generation, a phenomenon that gave rise to the field of thermoplasmonics, attracting much attention in the context of life science applications including cancer therapy and neuronal photostimulation. The latter is of particular interest since the local heat generation under pulsed laser excitation can induce an action potential in neurons. However, the measure of the local temperature in situ during neuronal photostimulation has yet to be shown. Here we propose a hybrid construct in which water-soluble conjugated polymers, apart from acting as fluorescent nanothermometer, serve as a scaffold for a monolayer of gold bipyramids as a heat source (Figure 1: (a) Chemical structure and (b) fluorescence spectra of the conjugated polymers, (c) scheme of the system comprising a monolayer of gold bipyramids and conjugated polymer matrix, (d) macroscopic image of the substrate under white light and the UV lamp, (e) SEM image of the substrate showing randomly distributed nanoparticles, (f) TEM image of gold bipyramids monolayer and (g) UV-Vis-NIR spectrum of the nanocrystals in the solution.(a) Chemical structure and (b) fluorescence spectra of the conjugated polymers, (c) scheme of the system comprising a monolayer of gold bipyramids and conjugated polymer matrix, (d) macroscopic image of the substrate under white light and the UV lamp, (e) SEM image of the substrate showing randomly distributed nanoparticles, (f) TEM image of gold bipyramids monolayer and (g) UV-Vis-NIR spectrum of the nanocrystals in the solution.). Using the Fluorescence Lifetime Imaging Microscopy (FLIM) one can measure the change of fluorescence lifetime of conjugate polymers matrix as a function of local temperature under infrared light irradiation. The biocompatibility and structural diversity of layer-by-layer nanoarchitectures pave the way for integrating the proposed system into a biological interface.Peer reviewe

On-demand reversible switching of the emission mode of individual semiconductor quantum emitters using plasmonic metasurfaces

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications, such as quantum information, quantum communication, and quantum cybersecurity. At the core of these applications lies the quantum emitter (QE), a precisely controllable generator of either single photons or photon pairs. Semiconductor QEs, such as perovskite nanocrystals and semiconductor quantum dots, have shown much promise as emitters of pure single photons, with the potential for generating photon pairs when hybridized with plasmonic nanocavities. In this study, we have developed a system in which individual quantum emitters and their ensembles can be traced before, during, and after the interaction with an external plasmonic metasurface in a controllable way. Upon coupling the external plasmonic metasurface to the QE array, the individual QEs switch from the single-photon emission mode to the multiphoton emission mode. Remarkably, this method preserves the chemical structure and composition of the QEs, allowing them to revert to their initial state after decoupling from the plasmonic metasurface. This significantly expands the potential applications of semiconductor QEs in quantum technologies

On-demand reversible switching of the emission mode of individual semiconductor quantum emitters using plasmonic metasurfaces

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications as quantum information, quantum communication and quantum cybersecurity. The central building block for these applications is a quantum emitter (QE), a controllable source of single photons or photon pairs. Semiconductor QEs such as perovskite nanocrystals (PNCs) and semiconductor quantum dots (QDs) have been demonstrated to be a promising material for pure single-photon emission, and their hybrids with plasmonic nanocavities may serve as sources of photon pairs. Here we have designed a system in which individual quantum emitters and their ensembles can be traced before, during, and after the interaction with the external plasmonic metasurface in controllable way. Upon coupling the external plasmonic metasurface to the array of QEs, the individual QEs switch from single-photon to photon-pair emission mode. Remarkably, this method does not affect the chemical structure and composition of the QEs, allowing them to return to their initial state after decoupling from the plasmonic metasurface. By employing this approach, we have successfully demonstrated the reversible switching of the ensemble of individual semiconductor QEs between single-photon and photon pair emission modes. This significantly broadens the potential applications of semiconductor QEs in quantum technologies

Metal-polymer heterojunction in colloidal-phase plasmonic catalysis

[Image: see text] Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD(+) to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal–polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD(+) reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity