Territoires européens et transport ferroviaire

Woessner, Raymond

doi:10.3917/popav.726.0014

Cited by 8 publications

(3 citation statements)

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“…19 In order to visualize plasmons and characterize their propagation, we used a scattering-type near-field optical microscope in photocurrent mode. 10,20,21 We operated the microscope in the Terahertz (THz) frequency range (we chose a laser frequency of ω 2π = 3.11 THz), as this allowed us to probe down to the lowest plasmon velocities while respecting the minimum-wavelength limitations of the near-field probe. 22 In order to detect the photocurrent, we left a narrow split in the AuPd metal layer (Fig.…”

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confidence: 99%

Tuning quantum nonlocal effects in graphene plasmonics

Lundeberg

Gao

Asgari

et al. 2017

Science

328

353

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The response of an electron system to electromagnetic fields with sharp spatial variations is strongly dependent on quantum electronic properties, even in ambient conditions, but difficult to access experimentally. We use propagating graphene plasmons, together with an engineered dielectric-metallic environment, to probe the graphene electron liquid and unveil its detailed electronic response at short wavelengths. The near-field imaging experiments reveal a parameter-free match with the full theoretical quantum description of the massless Dirac electron gas, in which we identify three types of quantum effects as keys to understanding the experimental response of graphene to short-ranged terahertz electric fields. The first type is of single-particle nature and is related to shape deformations of the Fermi surface during a plasmon oscillation. The second and third types are a many-body effect controlled by the inertia and compressibility of the interacting electron liquid in graphene. We demonstrate how, in principle, our experimental approach can determine the full spatiotemporal response of an electron system.The quantum physics of electron systems involves complex short-distance interactions and motions that depend sensitively on electron correlations and Fermi surface deformations.1,2 These are often considered irrelevant in optical and transport measurements, which probe the response to electrical fields with long length scales. When free electron systems are driven by electric fields varying rapidly in both time and space, however, the response pattern in dynamical current reveals these complex shortrange effects. This aspect of electron response, known as non-locality or spatial dispersion in conductivity, arises due to the internal spreading of energy via the moving electrons. Even in ambient conditions (as Fermi liquid parameters depend on temperature weakly 1,2 ), the spatial dispersion in an electron system retains a detailed connection to Fermi-surface and electron-electron correlation effects, and hence it provides a unique window into quantum theories of electron systems without requiring extremes of low temperature or high magnetic field. Unfortunately, these quantum regimes cannot be accessed by standard optical and transport probes.Plasmons-electric waves resulting from an inertial electron conductivity combined with electric restoring * Marco.Polini@iit.it † frank.koppens@icfo.eu forces-can act as a carrier of the spatiotemporal electric fields necessary to probe non-locality. All systems exhibit non-local effects for plasmon wavelengths approaching the electronic Fermi wavelength λ F , which has been confirmed in experimental studies of metals and semiconductor two-dimensional (2D) electron gases. 3-5 Such experiments have however led to challenges in quantitative interpretation, due to strong interactions that go beyond standard (e.g. random phase approximation) theoretical treatments, 3,4 and possible complications by edge effects and tunneling. 5-9In graphene, it is possible to access a diff...

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confidence: 99%

Tuning quantum nonlocal effects in graphene plasmonics

Lundeberg

Gao

Asgari

et al. 2017

Science

328

353

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“…If one is not interested in oblique beams and only requires wave propagation towards +𝑦, moving the dipole further away from graphene is enough to filter the high-𝑘 ⃗⃗ components that would couple to those directions. This separation, 𝑧 𝑑𝑖𝑝 , can be controlled with a moving nanotip or with a dielectric spacer [75][76][77][78]. Fig.…”

Section: Then We Derive the Dispersion Relation Of The Supported Plas...mentioning

confidence: 99%

Nonreciprocal and collimated surface plasmons in drift-biased graphene metasurfaces

Correas-Serrano

Gómez‐Díaz

2019

Phys. Rev. B

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We explore the unusual non-reciprocal and diffraction-less properties of surface plasmon polaritons propagating in drift-biased graphene-based metasurfaces. We show that applying a drift-current on a graphene sheet leads to extremely asymmetric in-plane modal dispersions from terahertz to infrared frequencies, associated with plasmons with low-loss (high-loss and ultra-high confinement) traveling along (against) the bias. Strikingly, truly unidirectional wave propagation is prevented by the intrinsic nonlocal response of a graphene, a mechanism that shapes the energy flow over the surface. We also show that highly-directive hyperbolic plasmons completely immune to backscattering propagate obliquely along the drift in nanostructured graphene. Finally, we discuss how spin-orbit interactions can be exploited in this platform to efficiently launch collimated plasmons along a single direction while maintaining giant non-reciprocal responses. Our findings open a new paradigm to excite, collimate, steer, and process surface plasmons over a broad frequency band. PACS: 32.10.Dk, 42.25.Fx, 73.20.Mf, 78.67.Wj The Lorentz reciprocity principle constrains the performance of photonic systems by enforcing identical responses when observation and excitation points are interchanged [1][2][3][4]. Recently, nonreciprocal surface plasmons-polaritons (SPPs) have merged the concept of one-wave optical propagation with the confinement and manipulation of light in engineered surfaces much smaller than the wavelength [5][6][7][8][9][10]. The possibility to collimate and dynamically control the direction of these waves within a surface opens exciting venues to realize miniaturized all-photonic integrated systems [11] and may enable new applications in sub-diffractive nanophotonics, including sensing, imaging, and computing. Even though

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“…Les différents types et échelles de trafics coexistent effectivement au sein d'une même organisation circulatoire. L'efficacité du pilotage du système national de franchissement repose sur la capacité à inscrire la gestion de chacun des axes concernés dans une double proximité : l'environnement réticulaire immédiat et le corridor d'échelle continentale Rhin-Alpes (Rotterdam-Gênes via la rive droite du Rhin et la Suisse) [Woessner 2016, Beyer 2019. En lien avec la mise en exploitation du tunnel de base du Lötschberg, un centre de gestion des circulations de BLS (Berne-Lötschberg-Simplon, une entreprise ferroviaire suisse) est inauguré à Spiez pour gérer une large portion du réseau suisse allant de Gümlingen au Nord, Sierre à l'Ouest et Domodossola au Sud, là encore indépendamment de la propriété de l'infrastructure.…”

Section: Faire-corridor Par La Connectivité : Un Processus De Réticularisationunclassified

Faire-corridor : le corridor comme agencement politico-réticulaire

Sutton¹

2019

bagf

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Territoires européens et transport ferroviaire

Cited by 8 publications

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Tuning quantum nonlocal effects in graphene plasmonics

Tuning quantum nonlocal effects in graphene plasmonics

Nonreciprocal and collimated surface plasmons in drift-biased graphene metasurfaces

Faire-corridor : le corridor comme agencement politico-réticulaire

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