ORBi Collection: Physics
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Anticoherence of spin states with pointgroup symmetries
http://hdl.handle.net/2268/188553
Title: Anticoherence of spin states with pointgroup symmetries
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<br/>Author, coauthor: Baguette, Dorian; Damanet, François; Giraud, Olivier; Martin, John
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<br/>Abstract: We investigate multiqubit permutationsymmetric states with maximal entropy of entanglement. Such states can be viewed as particular spin states, namely anticoherent spin states. Using the Majorana representation of spin states in terms of points on the unit sphere, we analyze the consequences of a pointgroup symmetry in their arrangement on the quantum properties of the corresponding state. We focus on the identification of anticoherent states (for which all reduced density matrices in the symmetric subspace are maximally mixed) associated with pointgroupsymmetric sets of points. We provide three different characterizations of anticoherence and establish a link between point symmetries, anticoherence, and classes of states equivalent through stochastic local operations with classical communication. We then investigate in detail the case of small numbers of qubits and construct infinite families of anticoherent states with pointgroup symmetry of their Majorana points, showing that anticoherent states do exist to arbitrary order.

Defining the Observables for Quarks and Gluons Orbital Angular Momentum Distributions
http://hdl.handle.net/2268/188481
Title: Defining the Observables for Quarks and Gluons Orbital Angular Momentum Distributions
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<br/>Author, coauthor: Liuti, S.; Courtoy, Aurore; Goldstein, G. R.; Gonzalez Hernandez, J. O.; Rajan, A.
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<br/>Abstract: We present a critical discussion of the observables that have been recently put forth to describe quarks and gluons orbital angular momentum distributions. Starting from a standard parameterization of the energy momentum tensor in QCD one can single out two forms of angular momentum, a socalled kinetic term, generally associated with the Ji decomposition, and a canonical term from the Jaffe Manohar decomposition. Orbital angular momentum has been connected to a Generalized Transverse Momentum Distribution (GTMD), for the canonical term, and to a twist three Generalized Parton Distribution for the kinetic term. We argue that while the latter appears as an azymuthal angular modulation in the longitudinal target spin asymmetry in deeply virtual Compton scattering, due to parity constraints, the GTMD associated with canonical angular momentum cannot be measured in a similar set of experiments.
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<br/>Commentary: Proceedings, Theory and Experiment for Hadrons on the LightFront (Light Cone 2014)

Dihadron fragmentation functions and transversity
http://hdl.handle.net/2268/188480
Title: Dihadron fragmentation functions and transversity
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<br/>Author, coauthor: Radici, M.; Courtoy, Aurore; Bacchetta, A.
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<br/>Abstract: We present preliminary results for an updated extraction of the transversity parton distribution based on the analysis of pionpair production in deepinelastic scattering off transversely polarized targets in collinear factorization. Data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity, while dihadron fragmentation functions are taken from the semiinclusive production of two pion pairs in backtoback jets in e+e annihilation. The latter data from Belle have been reanalyzed using the replica method and a more realistic estimate of the uncertainties on the chiralodd interference fragmentation function has been obtained. After encoding this piece of information into the deepinelastic scattering cross section, the transversity has been reextracted by using the most recent and more precise COMPASS data for proton target. This picture represents the current most realistic estimate of the uncertainties on our knowledge of transversity. The preliminary results indicate that the valence up component seems smaller and with a narrower error band than in previous extraction. © 2015 Owned by the authors, published by EDP Sciences.

25 novembre 2015 : cent ans de Relativité
http://hdl.handle.net/2268/188473
Title: 25 novembre 2015 : cent ans de Relativité
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<br/>Author, coauthor: De Rop, Yves
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<br/>Abstract: La théorie proposée par Einstein au début du XXe siècle porte bien mal son nom; car si, historiquement, l'accent fut mis d'abord sur la relativité de certaines notions (en particulier, la mesure de l'intervalle de temps écoulé entre deux événements donnés), on a compris par la suite qu'elle reposait plus fondamentalement sur l'existence de quantités absolues, c'estàdire, dont la mesure est identique pour tous les observateurs, quel que soit leur état de repos ou de mouvement. Ces quantités sont inconnues de la mécanique de Newton, laquelle ne reconnaît qu'un seul invariant : le temps. Ce texte cherche à retracer, avec un minimum de formalisme, comment s'est imposé un nouveau cadre géométrique pour la physique, dominé par cette exigence d'invariance des mesures spatiotemporelles et intégrant une description révolutionnaire de la gravitation.

BeyondStandardModel Tensor Interaction and Hadron Phenomenology
http://hdl.handle.net/2268/188420
Title: BeyondStandardModel Tensor Interaction and Hadron Phenomenology
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<br/>Author, coauthor: Courtoy, Aurore; Baeßler, Stefan; González–Alonso, Martín; Liuti, Simonetta

Thermal conductivity in PbTe from first principles
http://hdl.handle.net/2268/188321
Title: Thermal conductivity in PbTe from first principles
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<br/>Author, coauthor: Romero, A. H.; Gross, E. K. U.; Verstraete, Matthieu; Hellman, Olle

Realspace grids and the Octopus code as tools for the development of new simulation approaches for electronic systems
http://hdl.handle.net/2268/188320
Title: Realspace grids and the Octopus code as tools for the development of new simulation approaches for electronic systems
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<br/>Author, coauthor: Andrade, Xavier; Strubbe, David; De Giovannini, Umberto; Larsen, Ask Hjorth; Oliveira, Micael J. T.; AlberdiRodriguez, Joseba; Varas, Alejandro; Theophilou, Iris; Helbig, Nicole; Verstraete, Matthieu; others

Correction to Aluminum Conducts Better than Copper at the Atomic Scale: A FirstPrinciples Study of Metallic Atomic Wires
http://hdl.handle.net/2268/188319
Title: Correction to Aluminum Conducts Better than Copper at the Atomic Scale: A FirstPrinciples Study of Metallic Atomic Wires
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<br/>Author, coauthor: Simbeck, Adam J.; Lanzillo, Nick; Kharche, Neerav; Verstraete, Matthieu; Nayak, Saroj K.

Realtime measurement of temperature variation during nanosecond pulsed laser induced contamination deposition
http://hdl.handle.net/2268/188318
Title: Realtime measurement of temperature variation during nanosecond pulsed laser induced contamination deposition
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<br/>Author, coauthor: Kokkinos, Dimitrios; Gailly, Patrick; Georges, Marc; Tzeremes, Georgios; Rochus, Pierre; FleuryFrenette, Karl
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<br/>Abstract: In this paper a study of the heat generation during UV Laser Induced Contamination (LIC) and potentially
resulting subsequent thermal damage is presented. This becomes increasingly interesting when
optics with delicate coatings are involved. During LIC radiation can interact with outgassing molecules
both in the gas phase and at the surface, triggering chemical and photofixation reactions. This is a major
hazard, in particular for laser units operating under vacuum conditions such as for space applications.
The intense photon flux not only affects the contaminant deposition rate but also alters their chemical
structure that can increase their absorption coefficient. Over cumulative irradiation shots these molecules
formed deposits that increasingly absorb photons and produce heat as a byproduct of deexcitation eventually
leading to thermal damage. One could better asses the risk of the latter with the knowledge of
temperature during the contamination process. For this purpose thermoreflectance technique is used here
to estimate the temperature variation from pulse to pulse during contamination deposition through the
analysis of a temperaturedependent surface reflectance signal.

Thermoelectric properties of the unfilled skutterudite FeSb3 from first principles and Seebeck local probes
http://hdl.handle.net/2268/188240
Title: Thermoelectric properties of the unfilled skutterudite FeSb3 from first principles and Seebeck local probes
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<br/>Author, coauthor: Lemal, Sébastien; Ngoc, Nguyen; de Boor, Johanens; Ghosez, Philippe; Varignon, Julien; Klobes, Benedikt; Hermann, Raphaël; Verstraete, Matthieu
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<br/>Abstract: Using a combination of firstprinciples calculations and experimental transport measurements, we study the electronic and magnetic structure of the unfilled skutterudite FeSb3. We employ the hybrid functional approach for exchangecorrelation. The ground state is determined to be antiferromagnetic with an atomic magnetic moment of 1.6 μB/Fe. The Néel temperature Tn is estimated at 6 K, in agreement with experiments which found a paramagnetic state down to 10 K. The ground state is semiconducting, with a small electronic gap of 33 meV, also consistent with previous experiments on films. Charge carrier concentrations are estimated from Hall resistance measurements. The Seebeck coefficient is measured and mapped using a scanning probe at room temperature that yields an average value of 38.6 μV/K, slightly lower than the theoretical result. The theoretical conductivity is analyzed as a function of temperature and concentration of charge carriers.

Laser cooling of iron atoms
http://hdl.handle.net/2268/188086
Title: Laser cooling of iron atoms
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<br/>Author, coauthor: Huet, Nicolas

Energy Dispersion, Magnetism, and Transport in Three Condensed Matter Systems
http://hdl.handle.net/2268/188085
Title: Energy Dispersion, Magnetism, and Transport in Three Condensed Matter Systems
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<br/>Author, coauthor: Pike, Nicholas

Mesures de déformation par ESPI de la surface d’un miroir chauffé et comparaison avec simulations numériques
http://hdl.handle.net/2268/188033
Title: Mesures de déformation par ESPI de la surface d’un miroir chauffé et comparaison avec simulations numériques
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<br/>Author, coauthor: Languy, Fabian; Vandenrijt, JeanFrançois; SaintGeorges, Philippe; Georges, Marc

Système entièrement fibré et robotisé pour la génération d'ultrasons par laser à 532 nm et la détection par mixage d'ondes à 1064 nm
http://hdl.handle.net/2268/188032
Title: Système entièrement fibré et robotisé pour la génération d'ultrasons par laser à 532 nm et la détection par mixage d'ondes à 1064 nm
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<br/>Author, coauthor: Vandenrijt, JeanFrançois; Kokkinos, Dimitrios; Languy, Fabian; Thizy, Cédric; Simar, Juan Felipe; Georges, Marc

Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching
http://hdl.handle.net/2268/187911
Title: Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching
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<br/>Author, coauthor: Atxitia, U.; Ostler, Thomas; Chantrell, R. W.; ChubykaloFesenko, O.
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<br/>Abstract: Using largescale computer simulations, we thoroughly study the minimum energy required to ther mally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metalrare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electronphonon relaxation time. Importantly, we show that as the cooling time of the heated elec trons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures.

Ultrafast Magnetism at Complex Interfaces
http://hdl.handle.net/2268/187760
Title: Ultrafast Magnetism at Complex Interfaces
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<br/>Author, coauthor: Ostler, Thomas

Theory of plasmonic waves on a chain of metallic nanoparticles in a liquid crystal host
http://hdl.handle.net/2268/187676
Title: Theory of plasmonic waves on a chain of metallic nanoparticles in a liquid crystal host
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<br/>Author, coauthor: Pike, Nicholas; Stroud, David
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<br/>Abstract: Using the quasistatic approximation, we calculate the dispersion relations for plasmonic waves along a chain of
metallic nanoparticles when the host is a nematic or a cholesteric liquid crystal (NLC or CLC). If the director
of the NLC is perpendicular to the chain, the doubly degenerate transverse (T) branches split into two linearly
polarized branches. For a CLC with a twist axis parallel to the chain, the two T branches again split, but are
no longer linearly polarized. We illustrate these results numerically by calculating the dispersion relations for
Drude metal particles in either an NLC or a CLC.

Analysis of the timedependent electrical current in reversebiased pGeSn/nGe mesa diodes
http://hdl.handle.net/2268/187525
Title: Analysis of the timedependent electrical current in reversebiased pGeSn/nGe mesa diodes
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<br/>Author, coauthor: Baert, Bruno; Gupta, Somya; Gencarelli, Federica; Loo, Roger; Simoen, Eddy; Nguyen, Ngoc Duy

Surface Constrained Elastic Rods with Application to the Sphere
http://hdl.handle.net/2268/187483
Title: Surface Constrained Elastic Rods with Application to the Sphere
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<br/>Author, coauthor: Huynen, Alexandre; Detournay, Emmanuel; Denoël, Vincent
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<br/>Abstract: The unilateral contact between an elastic rod and a rigid surface is encountered in numerous biological and engineering applications. Along continuous contacts, the centerline of the rod reflects the geometry of the constraining surface. This restriction of the rod axis to surface bound configurations enters its local equilibrium through a reaction pressure which ensures the compatibility between the deformation and the restraint geometry. The classic equations governing the static equilibrium of elastic rods are particularized to surface bound configurations by (i) specifying the location of the rod axis in terms of its coordinates in the parameter space associated with the constraining surface parameterization, and (ii) characterizing the orientation of its material frame through its rotation with respect to the surface normal. This formulation, which emphasizes the relations between the rod configuration and the geometry of the constraint, also leads to an expression for the reaction pressure. This approach is then validated on a spherical surface by comparing with known solutions for elastic curves, i.e., inextensible and twist free rods.

Photodissociation of the carbon monoxide dication in the 3 Sigma manifold: Quantum control simulation towards the C2+ + O channel
http://hdl.handle.net/2268/187464
Title: Photodissociation of the carbon monoxide dication in the 3 Sigma manifold: Quantum control simulation towards the C2+ + O channel
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<br/>Author, coauthor: Vranckx, Stephane; Loreau, Jerome; Vaeck, Nathalie; Meier, christoph; Desouter, Michèle
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<br/>Abstract: The photodissociation and laser assisted dissociation of the carbon monoxide dication X3Π CO2+ into
the 3Σ− states are investigated. Ab initio electronic structure calculations of the adiabatic potential
energy curves, radial nonadiabatic couplings, and dipole moments for the X 3Π state are performed
for 13 excited 3Σ− states of CO2+. The photodissociation cross section, calculated by timedependent
methods, shows that the C+ + O+ channels dominate the process in the studied energy range. The
carbon monoxide dication CO2+ is an interesting candidate for control because it can be produced in
a single, long lived, v = 0 vibrational state due to the instability of all the other excited vibrational
states of the ground 3Π electronic state. In a spectral range of about 25 eV, perpendicular transition
dipoles couple this 3Π state to a manifold of 3Σ− excited states leading to numerous C+ + O+
channels and a single C2+ + O channel. This unique channel is used as target for control calculations
using local control theory. We illustrate the efficiency of this method in order to find a tailored
electric field driving the photodissociation in a manifold of strongly interacting electronic states.
The selected local pulses are then concatenated in a sequence inspired by the “laser distillation”
strategy. Finally, the local pulse is compared with optimal control theory.