Breaking Bad | EPFL Graph Search

Breaking Bad, ou Breaking Bad : Le Chimiste au Québec, est une série télévisée américaine en de , créée par Vince Gilligan, diffusée simultanément du au sur AMC aux États-Unis et au Canada, et ensuite sur Netflix. La série se concentre sur Walter White, un professeur de chimie surqualifié et père de famille, qui, ayant appris qu'il est atteint d'un cancer du poumon en phase terminale, sombre dans le crime pour assurer l'avenir financier de sa famille. Pour cela, il se lance dans la fabrication et la vente de méthamphétamine avec l'aide de l'un de ses anciens élèves, Jesse Pinkman. L'histoire se déroule à Albuquerque, au Nouveau-Mexique. Breaking Bad remporte de nombreuses récompenses : dont quatre du meilleur acteur pour Bryan Cranston, trois de meilleur acteur dans un second rôle pour Aaron Paul, deux de meilleure actrice dans un second rôle pour Anna Gunn, deux de meilleure série télévisée dramatique. Bryan Cranston a été nommé quatre fois au Golden Globe et le remporte en 2014. Il a également été nommé cinq fois au Screen Actors Guild Award, remportant la récompense en 2012 et 2013. Par ailleurs, Breaking Bad reçoit un large succès critique au fil des saisons. La cinquième saison a eu un score de 99 sur 100 sur le site Metacritic. En 2013, la Writers Guild of America la nomme des séries les mieux écrites de l'histoire de la télévision. Enfin, le magazine The Hollywood Reporter classe Breaking Bad comme la série américaine derrière Friends, alors que Esquire la place série dramatique après Les Soprano. Walter « Walt » White est professeur de chimie dans une école secondaire. Il vit à Albuquerque, au Nouveau-Mexique, avec son fils handicapé moteur et son épouse enceinte. Le lendemain de son cinquantième anniversaire, on lui diagnostique un cancer du poumon en phase terminale avec une espérance de vie estimée à deux ans. Tout s'effondre pour lui. Il décide alors de mettre en place un laboratoire et un trafic de méthamphétamine pour assurer un avenir financier confortable à sa famille après sa mort, en s'associant à Jesse Pinkman, un de ses anciens élèves devenu petit trafiquant.

Interaction of Confined Polaritons in Microcavity Structures

Morteza Navadeh Toupchi

A polariton is a quasiparticle formed from the coupling of a confined photon in a cavity to electronic excitation, like exciton in a semiconductor. This dissertation reports on series of experiments in confined polariton interaction by design, fabrication, and characterization of semiconductor microcavity structures operating in strong or weak coupling regime. In the first part of the thesis, we mainly concentrate on the optical study of the 2D microcavity sample, including spin-dependent lower-upper polariton cross interactions by pump-probe spectroscopy technique, supported by theoretical analyses and numerical simulations based on Gross-Pitaevskii equations. In particular, we present a scattering resonance behavior via an exciton molecule (biexciton) when polaritons from both the upper and lower branches with anti-parallel spins are involved through a polaritonic cross Feshbach resonance. This demonstration will permit the control of the polariton interbranch scattering. The second part of the thesis is dedicated to the design and fabrication of the potentials where the photonic part of polaritons is confined laterally by adjusting the thickness of the cavity layer locally in so-called mesa structures. By engineering a periodic lattice of mesas on a two-dimensional microcavity, it is possible to couple confined polariton modes of nearby mesas to establish an optical lattice analogous to the crystalline semiconductorsâ electronic band structures. We especially demonstrate the localization of light with a lasing mode at the edge of the Brillouin zone in a two-dimensional triangular lattice. We produce a self-trapping of light by optically inducing a local breaking of the strong-coupling regime of excitons to photons. In the weak coupling regime, we control the confined modes by the shape of the generated defect. We also reveal a controllable localization degree and experimental signature of the Anderson localization in microcavity polaritons by inducing positional disorder in the triangular lattice. The last part is devoted to the fabrication of sub-micron size mesas to enhance polariton interaction by confining them tightly and discuss the quantum correlation of polaritons by a Hanbury Brown and Twiss (HBT) setting toward polariton blockade.

EPFL2021

Origins of the macroscopic symmetry breaking in centrosymmetric phases of perovskite oxides

Sina Hashemi Zadeh

Many perovskite materials experience a temperature-driven phase transition at the Curie temperature from a non-centrosymmetric polar ferroelectric phase to a paraelectric phase, where polarization is lost. The paraelectric phase is usually centrosymmetric and therefore non-piezoelectric. However, ferroelectrics still show some forms of electro-mechanical coupling in their paraelectric phase like flexoelectricity, which is not symmetry limited and is practically strong in ferroelectrics. It has been shown that the flexoelectric coefficient of perovskite (Ba0.67,Sr0.33)TiO3 in its centrosymmetric paraelectric state at room temperature is up to three to four orders of magnitude larger than its theoretically predicted values. Such enormous discrepancy demonstrates that either the theory is unable to fully explain the flexoelectric response, or that another electro-mechanical mechanism is playing a role in the apparently large flexoelectric response of the material. It was found that Ba0.60Sr0.40TiO3 (BST6040) samples with apparently large flexoelectric coefficient exhibit symmetry breaking and consequently exhibit forbidden piezoelectric- and pyroelectric-like behavior in its paraelectric phase. In this thesis work, our interest lies in describing and interpreting the conditions where breaking of the symmetry is not associated with the external field nor with the flexoelectricity, but is proper to the material. Origins and mechanism of symmetry breaking were investigated in two different cases: local breaking of centrosymmetry; and macroscopic symmetry breaking. The local breaking of the centrosymmetry may refer to the existence of microscopic polar entities and/or disordered displacement of ions in the unit cell. The global symmetry breaking could be associated with a non-uniform distribution of charged defects and/or the coupling of polar nanoâregions with the strain gradient in the sample. We compared dielectric, elastic, and pyroelectric properties of the Ba1-xSrxTiO3 (BST) family, pure BaTiO3 in perovskite (p-BTO) and hexagonal (h-BTO) forms, and SrTiO3 to study the governing mechanisms of symmetry breaking. In addition, the atomic structure of BST6040 was studied by high resolution scanning transmission electron microscopy for direct evidence of polar regions and to understand their exact nature and origin. According to experimental data, the paraelectric phase of p-BTO shows local and global breaking of nominal centrosymmetricity and possesses microscopic and macroscopic polarizations, which are associated with precursors of the ferroelectric phase ordered by the strain gradient in the sample. On the other hand, h-BTO does not exhibit macroscopic pyroelectric response because the precursors are paraelectric-ferroelastic at room temperature, and therefore non-polar. Studying the material response to dynamic electric field showed that the Rayleigh-like relation, which describes dynamics of domain walls in a random pinning environment, cannot describe the dynamics of polar entities in these materials. Results of our high-resolution atomic studies showed distinct static polar clusters with the average size of few nanometers where A-site, B-site and O ions are displaced from their ideal cubic positions. We believe that all presented experimental data can be consistently explained by the presence of microscopic precursors of the ferroelectric phase and their interaction with the strain gradient in the material.

EPFL2017