Matériaux et Phénomènes Quantiques
Présentation
The laboratory « Matériaux et Phénomènes Quantiques » (Quantum Materials and Phenomena) is a joint research unit (UMR) of University Paris Diderot and CNRS. It involves about 120 people in total with a permanent staff of 51.
The laboratory specializes in the study of frontier quantum materials and in the development of novel quantum devices. These activities rely on a large spectrum of theoretical and experimental expertise in material physics, transport and optics, and technological platforms of clean-room fabrication, spectroscopy and high-resolution electronic microscopy.
The activities of the laboratory span:
- novel materials at the nanoscale: nanocrystals, functionalized nanotubes, multiferroics, 2D materials, etc.
- novel phases of matter: quantum fluids of light, ultrastrong coupling in cavity, unconventional superconductivity, strongly correlated systems, topological phases, etc.
- nano-optical systems: optomechanics, nonlinear nanophotonics, nanoplasmonics, etc.
- quantum engineering and quantum information: quantum optoelectronic devices, quantum photonic circuits, trapped ions, hybrid organic/inorganic devices, surface and interface engineering.
Current projects of the laboratory include the development of novel probes for the investigation of quantum materials, such as time-resolved Raman spectroscopy, optomechanical atomic force microscopy, and scanning tunneling microscopy under optical excitation. Reciprocally, frontier materials are being tested as building blocks to realize novel functionalities in optomechanical sensors, nonlinear and quantum photonics devices, or in cavity embedded transport experiments.
[hal-02490728] Interactions Between Topological Defects and Nanoparticles
Date: 17 Nov 2020 - 09:32
Desc: Liquid Crystal (LC) topological defects have been shown to trap nanoparticles (NPs) in the defect cores. The LC topological defects may thus be used as a matrix for new kinds of NP organizations templated by the defect geometry. We here study composites of LC smectic dislocations and gold NPs. Straight NP chains parallel to the dislocations are obtained leading to highly anisotropic optical absorption of the NPs controlled by light polarization. Combining Grazing Incidence Small Angle X-ray scattering (GISAXS), Rutherford Back Scattering (RBS), Spectrophotometry and the development of a model of interacting NPs, we explore the role of the Np size regarding the dislocation core size. We use NPs of diameter D = 6 nm embedded in an array of different kinds of dislocations. For dislocation core larger than the NP size, stable long chains are obtained but made of poorly interacting NPs. For dislocation core smaller than the NP size, the disorder is induced outside the dislocation cores and the NP chains are not equilibrium structures. However we show that at least half of these small dislocations can be filled, leading to chains with strongly enhanced electromagnetic coupling between the NPs. These chains are more probably stabilized by the elastic distortions around the defect cores, the distortion being enhanced by the presence of the grain boundary where the dislocations are embedded.
[hal-03701087] The Hong–Ou–Mandel experiment: from photon indistinguishability to continuous-variable quantum computing
Date: 21 Jun 2022 - 17:16
Desc: We extensively discuss the Hong–Ou–Mandel experiment by taking an original phase-space-based perspective. For this, we analyze time and frequency variables as quantum continuous variables in perfect analogy with position and momentum of massive particles or with the electromagnetic field’s quadratures. We discuss how this experiment can be used to directly measure the time-frequency Wigner function and implement logical gates in these variables. We also briefly discuss the quantum/classical aspects of this experiment providing a general expression for intensity correlations that make explicit the differences between a classical Hong–Ou–Mandel-like dip and a quantum one. Throughout the manuscript, we will often focus and refer to a particular system based on AlGaAs waveguides emitting photon pairs via spontaneous parametric down conversion, but our results can be extended to other analogous experimental systems and to various degrees of freedom.The Hong–Ou–Mandel experiment is a landmark in quantum optics, showing the bunching of indistinguishable bunch. In the present contribution, we give another perspective to this experiment based on a phase space representation of the continuous degrees of freedom of the single photons sent into the input arms of such interferometer. We show that the coincidence detection in the output ports of an Hong– Ou–Mandel interferometer is a direct measurement of the Wigner function of the produced photons in a given region of space, and we discuss how continuous degrees of freedom of single photons can be used in continuous variables quantum protocols, as quantum error correction and metrology. Our results open the perspective of broadening even more the applications of single photon-based quantum information-related protocols.[graphic not available: see fulltext][graphic not available: see fulltext]
[hal-00771207] Bell states generation on a III-V semiconductor chip at room temperature
Date: 1 Oct 2013 - 23:31
Desc: We demonstrate the generation of polarization-entangled photon pairs at room temperature and telecom wavelength in a AlGaAs semiconductor waveguide. The source is based on spontaneous parametric down conversion with a counterpropagating phase-matching scheme. The quality of the two-photon state is assessed by the reconstruction of the density matrix giving a raw fidelity to a Bell state of 0.83; a theoretical model, taking into account the experimental parameters, provides ways to understand and control the amount of entanglement. Its compatibility with electrical injection, together with the high versatility of the generated two-photon state, make this source an attractive candidate for completely integrated quantum photonics devices.
[hal-02450544] From Chains to Monolayers : Nanoparticle Assembly Driven by Smectic Topological Defects
Date: 15 Dec 2020 - 23:19
Desc: In this article, we show how advanced hierarchical structures of topological defects in the so-called smectic oily streaks can be used to sequentially transfer their geometrical features to gold nanospheres. We use two kinds of topological defects, 1D dislocations and 2D ribbon-like topological defects. The large trapping efficiency of the smectic dislocation cores not only surpasses that of the elastically distorted zones around the cores but also the one of the 2D ribbon-like topological defect. This enables the formation of a large number of aligned NP chains, within the dislocation cores that can be quasi-fully filled without any significant aggregation outside the cores. When the NP concentration is large enough to entirely fill the dislocation cores, the LC confinement varies from 1D to 2D. We demonstrate that the 2D topological defect cores induce a confinement that leads to planar hexagonal networks of NPs. We then draw the phase diagram driven by NP concentration, associated with the sequential confinements induced by these two kinds of topological defects. Owing to the excellent large-scale order of these defect cores, not only the NP chains but also the NP hexagonal networks can be oriented along the desired direction, suggesting a possible new route for the creation of either 1D or 2D highly anisotropic NP networks. In addition, these results open rich perspectives based on the possible creation of coexisting NP assemblies of different kinds, localized in different confining areas of a same smectic film that would thus interact thanks to their proximity but also would interact via the surrounding soft matter matrix.
Autres contacts
Université Paris Diderot - Paris 7
U.F.R. Physique
Bâtiment Condorcet
10, rue Alice Domon et Léonie Duquet
75205 PARIS CEDEX 13