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Matériaux et Phénomènes Quantiques
Présentation
Le laboratoire Matériaux et Phénomènes Quantiques (MPQ) est une unité mixte de recherche (UMR 7162) du CNRS et de l’Université Paris Diderot, installée sur le campus de Paris Rive Gauche. Elle est composée d’environ 120 personnes au total dont 51 permanent.e.s.
Le laboratoire est spécialisé dans l’étude des matériaux quantiques de frontière et dans le développement de dispositifs quantiques innovants. Ces activités reposent sur un large spectre de compétences théoriques et expérimentales alliant la physique des matériaux, le transport et l’optique, et des plateformes technologiques de salle blanche, de spectroscopie et de microscopie électronique haute résolution.
Les activités de recherche du laboratoire MPQ se déclinent selon les thèmes suivants :
- nouveaux matériaux à l’échelle nano : nanoparticules, nanocristaux, nanotubes fonctionnalisés, matériaux multiferroïques, etc.
- nouveaux états de la matière : fluides quantiques de lumière, couplage ultra-fort en cavité, supraconducteurs non-conventionnels, systèmes fortement corrélés, phases topologiques, etc.
- systèmes nano-optiques innovants : optomécanique, nanophotonique non-linéaire, nanoplasmonique, etc.
- ingénierie quantique et information quantique : composants optoélectroniques quantiques, circuits photoniques quantiques, ions piégés, matériaux et composants hybrides organique/inorganique, ingénierie des surfaces/interfaces.
Les projets actuels du laboratoire incluent le développement de nouvelles sondes pour l’étude des matériaux quantiques, comme la spectroscopie Raman résolue en temps, la microscopie AFM opto-mécanique et la microscopie tunnel sous excitation optique. Réciproquement, les matériaux de frontière sont mis à profit pour la réalisation de nouvelles fonctionnalités dans des senseurs optomécaniques, des circuits photoniques non-linéaires et quantiques, ou encore dans des expériences de transport mésoscopique en cavité optique.
[hal-01987572] Imaging the symmetry breaking of molecular orbitals in single-wall carbon nanotubes
Date: 21 1 月 2019 - 11:19
Desc: Carbon nanotubes have attracted considerable interest for their unique electronic properties. They are fascinating candidates for fundamental studies of one dimensional materials as well as for future molecular electronics applications. The molecular orbitals of nanotubes are of particular importance as they govern the transport properties and the chemical reactivity of the system. Here, we show for the first time a complete experimental investigation of molecular orbitals of single wall carbon nanotubes using atomically resolved scanning tunneling spectroscopy. Local conductance measurements show spectacular carbon-carbon bond asymmetry at the Van Hove singularities for both semiconducting and metallic tubes, demonstrating the symmetry breaking of molecular orbitals in nanotubes. Whatever the tube, only two types of complementary orbitals are alternatively observed. An analytical tight-binding model describing the interference patterns of pi orbitals confirmed by ab initio calculations, perfectly reproduces the experimental results.
[hal-03709229] Electronic properties of the five principal stackings of boron nitride moiré bilayers
Date: 29 6 月 2022 - 18:14
Desc: All theoretical calculations on boron nitride moiré bilayers report the properties of, at most, two possible stackings which preserve the monolayer hexagonal symmetry (i.e. the invariance upon rotations of 120$^\circ$). In this work, we demonstrate that, for a given moiré periodicity, the same symmetry is respected by five different stackings and not only two as always discussed in literature. We introduce some definitions and an appropriate nomenclature to identify unambiguously the twist angle and the stacking sequence of any BN bilayer with order-3 rotation symmetry. The nomenclature we introduce here and the method to calssify stacking sequences and the angles is completely general and can be applied to homobilayers of any hexagonal 2D materials. Moreover, we produce density functional theory predictions of the electronic structure of each of the five stacking sequences at six different twist angles and discuss the evolution of the gapwidth and band structure and as a function of these parameters. We show that the gap is indirect at any angle and in any stacking and we identify features that are conserved at any angle within the same stacking sequence.
[hal-02281355] Near Unity Absorption in Nanocrystal Based Short Wave Infrared Photodetectors using Guided Mode Resonators
Date: 30 10 月 2019 - 16:12
Desc: Nanocrystals appear as versatile building blocks for the design of low-cost optoelectronic devices. The design of infrared sensors based on nanocrystals is currently facing a key limitation: the short carrier diffusion length resulting from hopping transport makes that only a limited part of the incident light is absorbed. In order to enhance the device absorption, we use Guided Mode Resonance (GMR). The method appears to be quite versatile and is applied to both PbS and HgTe nanocrystals presenting respectively cut-off wavelengths at 1.7 and 2.6 µm. The designed electrodes present a large enhancement of the material responsivity around a factor of ≈250, reaching external quantum efficiency of 86% for PbS and 340% for HgTe. This increase of the response can be deconvoluted in a factor of 3 for the enhancement of the absorption and a factor of 80 for the photocurrent gain. The method can also be suited to finely tune the cut-off wavelength of the material thanks to geometrical parameters at the device level. The obtained devices are now only limited by the material noise.
[hal-01281368] The IVS data input to ITRF2014
Date: 2 Mar 2016 - 09:27
Desc: Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.gsfc.nasa.gov/) is a service of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU). The datasets published here are the results of individual Very Long Baseline Interferometry (VLBI) sessions in the form of normal equations in SINEX 2.0 format (http://www.iers.org/IERS/EN/Organization/AnalysisCoordinator/SinexFormat/sinex.html, the SINEX 2.0 description is attached as pdf) provided by IVS as the input for the next release of the International Terrestrial Reference System (ITRF): ITRF2014. This is a new version of the ITRF2008 release (Bockmann et al., 2009). For each session/ file, the normal equation systems contain elements for the coordinate components of all stations having participated in the respective session as well as for the Earth orientation parameters (x-pole, y-pole, UT1 and its time derivatives plus offset to the IAU2006 precession-nutation components dX, dY (https://www.iau.org/static/resolutions/IAU2006_Resol1.pdf). The terrestrial part is free of datum. The data sets are the result of a weighted combination of the input of several IVS Analysis Centers. The IVS contribution for ITRF2014 is described in Bachmann et al (2015), Schuh and Behrend (2012) provide a general overview on the VLBI method, details on the internal data handling can be found at Behrend (2013).
[hal-01987561] Thermodynamics versus kinetics in a morphology transition of nanoparticles
Date: 21 8 月 2023 - 10:19
Desc: The morphology of cobalt, palladium, and platinum nanoclusters grown on a gold surface is analyzed from both thermodynamic and kinetic viewpoints. Although the thermodynamic equilibrium shape as a function of cluster size is similar for all three elements and shows a morphology transition from monolayer to bilayer, only Co clusters meet their stable state and undergo a transition. Atomistic simulations on a picosecond to nanosecond time scale evidence kinetic limitations for Pt and Pd, and allow us to understand the experimentally observed morphology for the different species. It is shown that stress relaxation, by strongly influencing the energy activation for atom hopping from first to second cluster layer and the magnitude of vibration of the atoms, is the determinant parameter for the existence or absence of the cluster morphology transition. DOI: 10.1103/PhysRevB.87.155404
Autres contacts
Université Paris Diderot - Paris 7
U.F.R. Physique
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