Matériaux et Phénomènes Quantiques

MPQ

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Université Paris Diderot

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UFR Physique

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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-02467226] Universality at work – the local sine-Gordon model, lattice fermions, and quantum circuits

Date: 4 Feb 2020 - 21:17

Desc: We review the intriguing many-body physics resulting out of the interplay of a single, local impurity and the two-particle interaction in a one-dimensional Fermi system. Even if the underlying homogeneous correlated system is taken to be metallic, this interplay leads to an emergent quantum phase transition between metallic and insulating states. We show that the zero temperature critical point and the universal low-energy physics associated to it, is realized in two different models, the field theoretical local sine-Gordon model and spinless fermions on a lattice with nearest-neighbor hopping and two-particle interaction, as well as in an experimental setup consisting of a highly tunable quantum circuit. Despite the different high-energy physics of the three systems the universal low-energy scaling curves of the conductance as a function of temperature agree up to a very high precision without any free parameter. Overall this provides a convincing example of how emergent universality in complex systems originating from a common underlying quantum critical point establishes a bridge between different fields of physics. In our case between field theory, quantum many-body theory of correlated Fermi systems, and experimental circuit quantum electrodynamics.

[hal-01793753] Towards the experimental demonstration of quantum radiation pressure noise

Date: 16 Mayo 2018 - 22:02

Desc: [...]

[hal-02464078] On the Influence of Oxygen on the Degradation of Fe‐N‐C Catalysts

Date: 2 Feb 2020 - 21:58

Desc: Precious metal-free catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells are gaining momentum, with Fe-N-C catalysts comprising atomic FeN x sites the most promising candidate. Research and development is shifting from activity targets to improved stability of Fe-N-C catalysts in fuel cells. Their durability has hitherto been extensively studied using accelerated stress tests (AST) performed at room temperature and in inert-gas saturated acidic pH electrolyte. Here, we reveal stronger degradation of the Fe-N-C structure and four times higher ORR activity loss when performing load cycling AST in O2-vs. Ar-saturated pH 1 electrolyte. Raman spectroscopy results point towards strong carbon corrosion after AST in O2 , even when cycling at low potentials of 0.3-0.7 V vs. the reversible hydrogen electrode, while no corrosion occurred after any load cycling AST in Ar. The load cycling AST in O2 leads to the loss of a significant fraction of FeN x sites, as shown by energy dispersive X-ray spectroscopy analyses, and to the formation of Fe oxides. The results support that the unexpected carbon corrosion occurring at such low potential in the presence of O2 is due to reactive oxygen species produced between H 2 O 2 and Fe sites via Fenton reactions.

[hal-01996134] High-temperature electron microscopy study of ThO 2 microspheres sintering

Date: 28 Ene 2019 - 11:00

Desc: The behavior of ThO2 microspheres was investigated in situ at high temperature by electron microscopy, including HR-TEM and ESEM. The observation of isolated particles first allowed to describe the mechanisms driving the growth of crystallites within the microspheres, i.e. a combination of oriented attachment and solid-state diffusion, and to evaluate the associated activation energies. Polycrystalline and single-crystal two-grain systems were further investigated to monitor the formation of a neck during heat treatment. For single crystals, the topological evolution was found to agree well with the models, whereas the establishment of neck between two polycrystalline microspheres deviated from the expected trend, with the formation of intermediate large-size crystallites. Such modification was mainly assigned to the microstructures of the particles used, showing that the level of polycrystallinity of the powder and its initial porosity, which both arose from the synthesis method, must be considered carefully to evaluate its sintering capability.