Single-molecule study for a graphene-based nano-position sensor

In this study we lay the groundwork for a graphene-based fundamental ruler at the nanoscale. It relies on the efficient energy-transfer mechanism between single quantum emitters and low-doped graphene monolayers. Our experiments, conducted with dibenzoterrylene (DBT) molecules, allow going beyond ensemble analysis due to the emitter photo-stability and brightness. A quantitative characterization of the fluorescence decay-rate modification is presented and compared to a simple model, showing agreement with the $d^{-4}$ dependence, a genuine manifestation of a dipole interacting with a 2D material. With DBT molecules, we can estimate a potential uncertainty in position measurements as low as 5nm in the range below 30nm

Quantum nanophotonics in two-dimensional materials

The field of two-dimensional (2D) materials-based nanophotonics has been growing at a rapid pace, triggered by the ability to design nanophotonic systems with in situ control, unprecedented number of degrees of freedom, and to build material heterostructures from the bottom up with atomic precision. A wide palette of polaritonic classes have been identified, comprising ultraconfined optical fields, even approaching characteristic length-scales of a single atom. These advances have been a real boost for the emerging field of quantum nanophotonics, where the quantum mechanical nature of the electrons and polaritons and their interactions become relevant. Examples include quantum nonlocal effects, ultrastrong light–matter interactions, Cherenkov radiation, access to forbidden transitions, hydrodynamic effects, single-plasmon nonlinearities, polaritonic quantization, topological effects, and so on. In addition to these intrinsic quantum nanophotonic phenomena, 2D material systems can also be used as sensitive probes for the quantum properties of the material that carries the nanophotonics modes or quantum materials in its vicinity. Here, polaritons act as a probe for otherwise invisible excitations, for example, in superconductors, or as a new tool to monitor the existence of Berry curvature in topological materials and superlattice effects in twisted 2D materials. In this Perspective, we present an overview of the emergent field of 2D-material quantum nanophotonics and provide a future perspective on the prospects of both fundamental emergent phenomena and emergent quantum technologies, such as quantum sensing, single-photon sources, and quantum emitters manipulation. We address four main implications: (i) quantum sensing, featuring polaritons to probe superconductivity and explore new electronic transport hydrodynamic behaviors, (ii) quantum technologies harnessing single-photon generation, manipulation, and detection using 2D materials, (iii) polariton engineering with quantum materials enabled by twist angle and stacking order control in van der Waals heterostructures, and (iv) extreme light−matter interactions enabled by the strong confinement of light at atomic level by 2D materials, which provide new tools to manipulate light fields at the nanoscale (e.g., quantum chemistry, nonlocal effects, high Purcell enhancement).H.L.K. acknowledges support from the Government of Spain (FIS2017-91599-EXP; Severo Ochoa CEX2019-000910-S), Fundacio ' Cellex, Fundacio ' Mir-Puig, and Generalitat de Catalunya (CERCA, AGAUR, SGR 1656). Furthermore, the research leading to these results has received funding from the European Union's Horizon 2020 under Grant Agreements 785219 (Graphene flagship Core2), 881603 (Graphene flagship Core3), and 820378 (Quantum flagship). This work was also supported by the ERC TOPONANOP under Grant Agreement No. 726001. I.T. acknowledges funding from the Spanish Ministry of Science, Innovation and Universities (MCIU) and State Research Agency (AEI) via the Juan de la Cierva Fellowship No. FJC2018-037098-I. F.H.L. K. and A.R.-P. acknowledge BIST Ignite Programme Grant from the Barcelona Institute of Science and Technology (QEE2DUP). N.M.R.P. acknowledges support from the European Commission through the project "Graphene-Driven Revolutions in ICT and Beyond" (ref. No. 881603, CORE 3), COMPETE 2020, PORTUGAL 2020, FEDER, and the Portuguese Foundation for Science and Technology (FCT) through Project POCI-01-0145-FEDER028114, and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2019. N.A.M. is a VILLUM Investigator supported by VILLUM FONDEN (Grant No. 16498) and Independent Research Fund Denmark (Grant No. 702600117B). The Center for Nano Optics is financially supported by the University of Southern Denmark (SDU 2020 funding). The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation (Project No. DNRF103). J.C.W.S. acknowledges support from the National Research Foundation (NRF) Singapore under its NRF fellowship programme Award No. NRF-NRFF2016-05 and the Ministry of Education (MOE) Singapore under its MOE AcRF Tier 3 Award MOE2018-T3-1-002

Local Optical Probe of Motion and Stress in a multilayer graphene NEMS

Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics

First-principles study of an iron-based molecule grafted on graphene

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Surface-Enhanced Raman Signal for Terbium Single-Molecule Magnets Grafted on Graphene

We report the preparation and characterization of monolayer graphene decorated withfunctionalized single-molecule magnets (SMMs). The grafting ligands provide a homogeneous and selectivedeposition on graphene. The grafting is characterized by combined Raman microspectroscopy, atomic forcemicroscopy (AFM), and electron transport measurements. We observe a surface-enhanced Raman signal thatallowed us to study the grafting down to the limit of a few isolated molecules. The weak interaction throughcharge transfer is in agreement with ab initio DFT calculations. Our results indicate that both molecules andgraphene are essentially intact and the interaction is driven by van der Waals forces