Matériaux et Phénomènes Quantiques

MPQ

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Université Paris Diderot

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UFR Physique

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UMR

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CNRS

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-03709229] Electronic properties of the five principal stackings of boron nitride moiré bilayers

Date: 29 juin 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-01996212] Collapse of Critical Nematic Fluctuations in FeSe under Pressure

Date: 23 Mar 2022 - 10:49

Desc: [...]

[hal-03423946] Cavity-mediated electron hopping in disordered quantum Hall systems

Date: 10 nov 2021 - 11:19

Desc: We investigate the emergence of long-range electron hopping mediated by cavity vacuum fields in disordered quantum Hall systems. We show that the counter-rotating (anti-resonant) light-matter interaction produces an effective hopping between disordered eigenstates within the last occupied Landau band. The process involves a number of intermediate states equal to the Landau degeneracy: each of these states consists of a virtual cavity photon and an electron excited in the next Landau band with the same spin. We study such a cavity-mediated hopping mechanism in the dual presence of a random disordered potential and a wall potential near the edges, accounting for both paramagnetic coupling and diamagnetic renormalization. We determine the cavity-mediated scattering rates, showing the impact on both bulk and edge states. The effect for edge states is shown to increase when their energy approaches the disordered bulk band, while for higher energy the edge states become asymptotically free. We determine the scaling properties while increasing the Landau band degeneracy. Consequences on the quantum Hall physics and future perspectives are discussed.

[hal-03466714] (Invited) Porous Hollow PtNi/C Nanoparticles and Their Many Facets

Date: 6 déc 2021 - 10:40

Desc: [...]

[hal-03446040] Photonic kernel machine learning for ultrafast spectral analysis

Date: 24 nov 2021 - 12:08

Desc: We introduce photonic kernel machines, a scheme for ultrafast spectral analysis of noisy radio-frequency signals from single-shot optical intensity measurements. The approach combines the versatility of machine learning and the speed of photonic hardware to reach unprecedented throughput rates. We theoretically describe some of the key underlying principles, and then numerically illustrate the reached performances on a photonic lattice-based implementation. We apply the technique both to picosecond pulsed radio-frequency signals, on energy-spectral-density estimation and a shape classification task, and to continuous signals, on a frequency tracking task. The presented optical computing scheme is resilient to noise while requiring minimal control on the photonic-lattice parameters, making it readily implementable in realistic state-of-the-art photonic platforms.