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Dissertations / Theses on the topic 'Non relativistico'

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Published: 9 March 2023
Last updated: 10 March 2023

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1

BAIGUERA, STEFANO. "Developments in non-relativistic field theory and complexity." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/258694.

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Questa tesi si focalizza sullo studio di due ambiti di ricerca principali: teorie di campo non relativistiche e complessità olografica. Nella prima parte riesaminiamo la classificazione generale dell'anomalia di traccia per teorie di campo 2+1 dimensionali accoppiate a una geometria di Newton-Cartan e revisioniamo anche il metodo dell'heat kernel, che è utilizzato per studiare azioni effettive a un loop e permette quindi di calcolare le anomalie per una data teoria. Applichiamo questa tecnica per estrarre i coefficienti esatti dei termini di curvatura dell'anomalia di traccia sia per uno scalare che per un fermione liberi e non relativistici, trovando una relazione con l'anomalia conforme della controparte relativistica in 3+1 dimensioni che suggerisce l'esistenza di una versione non relativistica del teorema a su cui commentiamo. Proseguiamo l'analisi dello scalare e del fermione libero e non relativistico con il metodo dell'heat kernel accendendo una sorgente per la massa delle particelle: in questa geometria, troviamo che non c'è anomalia gravitazionale, ma l'anomalia di traccia non è invariante di gauge. In seguito consideriamo un modello specifico che realizza un'estensione supersimmetrica N=2 del gruppo di Bargmann in 2+1 dimensioni con superpotenziale non nullo, ottenuto dalla riduzione dimensionale lungo una direzione nulla del modello di Wess-Zumino relativistico. Controlliamo che il superpotenziale è protetto contro le correzioni quantistiche come nella controparte relativistica, così trovando une versione non relativistica del teorema di non rinormalizzazione. Inoltre, abbia una forte evidenza che la teoria è esatta a un loop, a causa della struttura causale del propagatore non relativistico e a causa della conservazione della massa. Nella seconda parte della tesi revisioniamo le congetture olografiche proposte da Susskind per descrivere l'evoluzione temporale del ponte di Einstein-Rosen in teorie gravitazionali: la complessità=volume e la complessità=azione. Queste quantità possono essere usate come un modo per studiare dualità, e noi consideriamo sia il volume che l'azione di buchi neri in spazi AdS_3 warped, che costituiscono delle deformazioni non banali dell'usuale AdS_3, aventi isometrie al bordo non relativistiche. In particolare, calcoliamo analiticamente la dipendenza temporale della complessità trovando una derivata temporale asintotica proporzionale al prodotto della temperatura di Hawking e dell'entropia di Bekenstein-Hawking. In questo contesto, esistono estensioni delle proposte olografiche quando lo stato duale in teoria dei campi è misto, cioé consideriamo soltanto una sottoregione del bordo. Calcoliamo la struttura delle divergenze ultraviolette, il comportamento sub/super-additivo della complessità e la sua dipendenza dalla temperatura per buchi neri warped in 2+1 dimensioni, quando la sottoregione è uno dei bordi disconnessi dello spaziotempo. Infine, calcoliamo analiticamente la complessità=azione per una sottoregione data da un segmento nella geometria del buco nero BTZ, dimostrando che è uguale alla somma di un termine divergente direttamente proporzionale alla lunghezza della sottoregione, più un termine proporzionale all'entropia di entanglement. Mentre questo risultato suggerisce un forte legame tra complessità ed entropia di entanglement, dimostriamo che nel caso di due segmanti disgiunti nella geometria del BTZ ci sono dei termini finiti aggiuntivi: quindi, la precedente elegante struttura rimane vera solo per le parti divergenti.
This thesis focuses on the investigation of two broad research areas: non-relativistic field theories and holographic complexity. In the first part we review the general classification of the trace anomaly for 2+1 dimensional field theories coupled to a Newton-Cartan background and we also review the heat kernel method, which is used to study one-loop effective actions and then allows to compute anomalies for a given theory. We apply this technique to extract the exact coefficients of the curvature terms of the trace anomaly for both a non-relativistic free scalar and a fermion, finding a relation with the conformal anomaly of the 3+1 dimensional relativistic counterpart which suggests the existence of a non-relativistic version of the a-theorem on which we comment. We continue the analysis of non-relativistic free scalar and fermion with the heat kernel method by turning on a source for the particle mass: on this background, we find that there is no gravitational anomaly, but the trace anomaly is not gauge invariant. We then consider a specific model realizing a N=2 supersymmetric extension of the Bargmann group in 2+1 dimensions with non-vanishing superpotential, obtained by null reduction of a relativistic Wess-Zumino model. We check that the superpotential is protected against quantum corrections as in the relativistic parent theory, thus finding a non-relativistic version of the non-renormalization theorem. Moreover, we find strong evidence that the theory is one-loop exact, due to the causal structure of the non-relativistic propagator together with mass conservation. In the second part of the thesis we review the holographic conjectures proposed by Susskind to describe the time-evolution of the Einstein-Rosen bridge in gravitational theories: the complexity=volume and complexity=action. These quantities may be used as a tool to investigate dualities, and we investigate both the volume and the action for black holes living in warped AdS_3 spacetime, which is a non-trivial modification of usual AdS_3 with non-relativistic boundary isometries. In particular, we analytically compute the time dependence of complexity finding an asymptotic growth rate proportional to the product of Hawking temperature and Bekenstein-Hawking entropy. In this context, there exist extensions of the holographic proposals when the dual state from the field theory side is mixed, i.e. we consider only a subregion on the boundary. We study the structure of UV divergences, the sub/super-additivity behaviour of complexity and its temperature dependence for warped black holes in 2+1 dimensions when the subregion is taken to be one of the two disconnected boundaries. Finally, we analytically compute the subregion action complexity for a general segment on the boundary in the BTZ black hole background, finding that it is equal to the sum of a linearly divergent term proportional to the size of the subregion and of a term proportional to the entanglement entropy. While this result suggests a strong relation of complexity with entanglement entropy, we find after investigating the case of two disjoint segments in the BTZ background that there are additional finite contributions: then the previous elegant structure holds only for the divergent parts.
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2

Moucherek, Fernando Marques de Oliveira. "INFLUÊNCIA DA VIOLAÇÃO DA SIMETRIA DE LORENTZ SOBRE A EQUAÇÃO DE DIRAC E O ESPECTRO DE HIDROGÊNIO." Universidade Federal do Maranhão, 2006. http://tedebc.ufma.br:8080/jspui/handle/tede/729.

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Made available in DSpace on 2016-08-18T18:19:29Z (GMT). No. of bitstreams: 1 fernando moucherek.pdf: 338779 bytes, checksum: b2cb977406951d20096081bf000e7975 (MD5) Previous issue date: 2006-10-20
In this work, one searchs to investigate the influence of violating terms of Lorentz and CPT (in "vectorial"and "axial"couplings ) on the equation of Dirac, and its non-relativistic limit. Firstly, its solutions of wave-planes, relation of dispersion and eigenvalues are gotten. After that, the limit of low energies is worked and determined the non-relativistic Hamiltonian. In the case of the vectorial coupling, the breaking terms do not induce any modification on the spectrum of hydrogen (in the presence or absence of external magnetic field), what it is in accordance with the fact of this background only to determine the displacement at the momentum of the system. In the case of the pseudo-vectorial coupling, however, the non-relativistic Hamiltonian possesss a term that modifies the spectrum, inducing an alteration of energy similar to Zeeman effect (in the absence of external magnetic field). Such effect is then used to establish the upper limit on the magnitude of background:bz < 10¡10eV . In the second part of this work, is analyzed the influence of a fixed background, violating of Lorentz, in a non-minimum coupling on the sector of fermions, on the equation of Dirac. The non-relativistic regime is considered and the Hamiltonian accomplished. The effect of this Hamiltonian on the spectrum of hydrogen is determined in calculations of first order (in the absence of external magnetic field), revealing the presence of energy shifting that modifies the fine structure of the spectrum and makes possible the imposition of a upper limit on the breaking product:gvz < 10¡14(eV )¡1. In the presence of external magnetic field, a correction of energy also is gotten, implying in the limit:gvz < 10¡25(eV )¡1. In the case where the non-minimum coupling is of the type torsion, no first order correction is shown in the absence of external field; in the presence of a external field, a second Zeeman effect is observed, implying in:gvz < 10¡25(eV )¡1. Such results show that the effect of Lorentz violating can more significantly be investigated in way to the presence of a external field.
Neste trabalho, busca-se investigar a influência de termos violadores de Lorentz e CPT (em acoplamentos "vetoriais"e "axiais") sobre a equação de Dirac, e seu limite não-relativistico. Primeiramente, são obtidas as suas soluções de onda-plana, relação de dispersão e autovalores. Em seguida, o limite de baixas energias é trabalhado e o Hamiltoniano não-relativistico determinado. No caso do acoplamento vetorial, os ter- mos de violação não induzem qualquer modificação sobre o espectro do hidrogênio (na presença ou ausência de campo magnético externo), o que está de acordo com o fato deste background determinar apenas um deslocamento no momento do sistema. No caso do acoplamento pseudo-vetorial, entretanto, o Hamiltoniano não-relativistico possui um termo que modifica o espectro, induzindo uma alteração de energia similar ao efeito Zee- man (na ausência de campo magnético externo). Tal efeito é então usado para estabelecer um limite superior sobre a magnitude do background: bz < 10¡10eV Na segunda parte deste trabalho, é analisada a influência de um background bz xo, violador de Lorentz, em acoplamento não-minimo sobre o setor de férmions, sobre a equação de Dirac. O regime não-relativistico é considerado e o Hamiltoniano estabelecido. O efeito deste Hamiltoniano sobre o espectro do hidrogênio é determinado em cálculos de primeira ordem (na ausência de campo magnético externo), revelando a presença de desvios de energia que modificam a estrutura fina do espectro e possibilitam a imposição de um limite superior sobre o produto de violação: gvz < 10¡14(eV )¡1. Na presença de campo magnético externo, uma correção de energia é também obtida, implicando no limite:gvz < 10¡25(eV )¡1.No caso em que o acoplamento não-minimo é do tipo torção, nenhuma correção de primeira ordem é exibida na ausência de campo externo; na presença de um campo externo, um segundo efeito Zeeman é observado, implicando emgvz < 10¡25(eV )¡1. Tais resultados mostram que o efeito de violação de Lorentz pode ser mais sensivelmente investigado em meio à presença de um campo externo.
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3

Kennedy, Piers. "Relativistic and non-relativistic scattering theory." Thesis, University of Sussex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399878.

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4

Timson, D. R. E. "Locality in non-relativistic and relativistic quantum mechanics." Thesis, University of St Andrews, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378971.

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5

Lee, R. J. S. "Ion-atom collisions at relativistic and non-relativistic energies." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368591.

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6

Gotti, Gianmarco. "D-Brane inflation in the non-relativistic and relativistic regimes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16960/.

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In this thesis we study inflation from a string theory point of view. The first part of the work is dedicated to reviewing how this mechanism can solve the main problems of the Standard Hot Big Bang (HBB) Cosmology and how it can be built in the context of General Relativity. The second part focuses on the application of the principles of string theory to inflation. In this framework an inflationary model can be viewed as an effective field theory in the super-gravity limit. In particular we concentrate on inflationary models in which the effective Lagrangian is obtained from the dimensional reduction of the Dirac-Born-Infeld (DBI) action, which describes the position and orientation of a $D7$-brane. This effective Lagrangian contains a non-trivial kinetic term. We study the effects of this non-trivial kinetic term on the speed of sound $c_s$, on the tensor-to-scalar ratio $r$ and on the spectral index $n_s$ in the case of monomial potentials, generalizing the work done by Ibanez and Pedro. We find that the system never enters the relativistic regime and therefore $c_s\simeq 1$. This justifies the truncation of the DBI action to second order derivatives. In the final chapter we see how the Swampland criteria, when applied to $DBI$ inflation, push the system into the relativistic regime and lead to a strong decrease of $c_s$.
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7

Tagliazucchi, Matteo. "Renormalization in non-relativistic quantum mechanics." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21030/.

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A problem of non-relativistic quantum mechanics solved using regularization and renormalization techniques is presented in this thesis. After a general introduction of these techniques, they are applied to a problem in classical electromagnetism and to the bound state of a single quantum particle subjected to a two-dimensional delta-function potential, that is divergent if computed naively solving directly the Schroedinger equation or using the theory of propagators. The regularization techniques used are the cutoff regularization and the dimensional one and they both leads to the same outcome. An effective field theory approach, in which the potential is regularized through the real space scheme, is also presented. After regularization has been performed, the potential is renormalized re-defining the coupling constant. The running of the renormalized coupling constant is also found, i.e. the renormalization group equation.
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8

Balasubramanian, Koushik. "Holographic view of non-relativistic physics." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79255.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 167-177).
Motivated by the AdS/CFT correspondence for relativistic CFTs, it seems natural to generalize it to non-relativistic CFTs. Such a dual description could provide insight into strong coupling phenomena observed in condensed matter systems. Scale invariance can be realized in non-relativistic theories in many ways. One freedom is the relative scale dimension of time and space, called the dynamical exponent z. In this thesis, we will mainly focus on the case where z = 2, however gravity duals for other values of z have also been found. In the first part of the thesis, we study NRCFTs that are Galilean invariant. Discrete light cone quantization (DLCQ) of V= 4 super Yang-Mills theory is an example of such a system with z = 2 scaling symmetry. A more realistic example of a system with the same set of symmetries is a system of cold fermions at unitarity. These non-relativistic systems respect a symmetry algebra known as the Schrödinger algebra. We propose a gravity dual that realizes the symmetries of the Schrödinger algebra as isometries. An unusual feature of this duality is that the bulk geometry has two extra dimensions than the CFT, instead of the usual one. The additional direction is a compact direction and shift symmetry along this direction corresponds to the particle number transformation. This solution can be embedded into string theory by performing a set of operations (known as the Null-Melvin twist) on AdS5 x S' solution of type IIB supergravity. This method also provides a way of finding a black hole solution which has asymptotic Schrödinger symmetries. The field theory dual of these gravity solutions happens to be a modified version of DLCQ V = 4 super Yang-Mills theory. The thermodynamics of these theories is very different from that of cold atoms. This happens to be a consequence of realizing the entire Schrödinger group as isometries of the spacetime. We give an example of a holographic realization in which the particle number symmetry is realized as a bulk gauge symmetry. In this proposal, the Schrödinger algebra is realized in the bulk without the introduction of an additional compact direction. Using this proposal, we find a confining solution that describes a non-relativistic system at finite density. We use the holographic dictionary to compute the conductivity of this system and it is found to exhibit somewhat unusual behavior. In the second part of the thesis we study gravity duals of Lifshitz theories. These are non-relativistic scale invariant theories that are not boost invariant. These theories do not have a particle number symmetry unlike the boost invariant NRCFTs. We present solutions of 1OD and 111D supergravity theories that are dual to Lifshitz theories. We present a black hole solution that is dual to a strongly interacting Lifshitz theory at finite temperature. We show that the finite temperature correlators in the interacting theories do not exhibit ultra-local behavior which was observed in free Lifshitz theories.
by Koushik Balasubramanian.
Ph.D.
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9

Lundhammar, Per. "A Non-Relativistic Model of Tetraquarks." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276232.

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In this thesis, a non-relativistic model of tetraquark in a diquark-antidiquark configuration is investigated. Using a variation of the Cornell potential, the Schrödinger equation is solved numerically, and the four-body problem of the tetraquark is separated into to three two-body problems. The splitting structure is accounted for by a spin-spin interaction term. Several numerical fits are made to different types of meson data to obtain the free parameters of the model, and subsequently, the masses of diquarks and tetraquarks with different constituents are determined. An introduction to the subject of exotic hadrons is presented as well as an overview of the experimental progress concerning tetraquarks. The results obtained in this thesis are then discussed by comparison with other relativistic models and experimental results.
I detta arbete undersöks en icke-relativistisk modell av tetrakvarkar i en dikvark-antidikvark- konfiguration. Genom att använda en variation av Cornellpotentialen löstes Schrödingerekvationen numeriskt och det fyrkroppsproblem som tetrakvarkar utgör delades upp i tre tvåkroppsproblem. Modellen tar även hänsyn till systemets spinn-spinn-koppling. Flera numeriska anpassningar gjordes för olika typer av mesondata för att bestämma de fria parametrarna i modellen. Därefter bestämdes massorna av dikvarkar och tetrakvarkar med olika sammansättningar av deras beståndsdelar. En introduktion till exotiska hadroner presenteras samt en översikt av de experimentella framstegen gällande tetrakvarkar. Resultaten diskuteras och jämförs med andra relativistiska modeller och experimentella resultat.
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Lei, Yang. "Singularities in holographic non-relativistic spacetimes." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11546/.

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We studied the physical meaning of tidal force singularities in non-relativistic spacetimes. Typical examples of such spacetimes include Lifshitz spacetimes, Schr\"{o}dinger spacetimes and hyperscaling violation spacetimes. First I will discuss the extension of singularity-free hyperscaling violation geometry. To understand the physical meaning of singularity in the deep non-relativistic IR bulk, I will calculate string scattering amplitudes to find a field theory interpretation of bulk singularity. Since geometric quantities like singularities or horizons are not physical observables in higher spin theory, we will discuss whether it is possible to resolve such singularities in non-relativistic spacetimes from higher spin theory context. We will show singularity resolution cannot be performed in $2+1$ dimensional higher spin theory. Finally, we will give an explicit construction of Schr\"{o}dinger spacetime solutions in $3+1$ dimensional higher spin theory.
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Burton, David A. "Slender elastic media and the gravitational field." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322890.

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12

Beck, Scott J. "Application of Self-Adjoint Extensions to the Relativistic and Non-Relativistic Coulomb Problem." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1465577450.

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13

Eiras, Fernández Dolors. "Facets of non-relativistic Effective Field Theories." Doctoral thesis, Universitat de Barcelona, 2002. http://hdl.handle.net/10803/1590.

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Collected papers where problems involving non-relativistic systems are solved by means of a proper Effective Field Theory. Those problems include the calculation of the lifetime of pionium, the lepton finite mass corrections from vacuum polarization to non-relativistic bound state energies and wave function at the origin, the analysis of the Nucleon-Nucleon OPE (one pion exchange) interactions from a renormalization point of view and heavy quarkonia P-wave hadronic decays.
Aquesta tesi presenta un recull de publicacions on problemes relatius a sistemes no relativistes són adreçats mitjançant l'apropiada EFT (Effective Field Theory). Entre les esmentades aplicacions s'inclou el càlcul de la vida mitjana del pionium, correccions a les energies d'estats lligats i funció d'ona a l'origen degudes a la massa finita del leptó en la polarització del buit, l'anàlisi de la interacció OPE (one pion exchange) des del punt de vista de la seva renormalització i, finalment, decaiments hadrònics d'ones P en "heavy quarkonia".
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Baxter, Colin. "Gauge transformations in non-relativistic quantum electrodynamics." Thesis, University of Essex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292876.

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15

Moreno-Gelos, Quentin. "Non-relativistic collisionless shocks in Laboratory Astrophysics." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0427/document.

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Les chocs sans collision sont omniprésents dans l'Univers, notamment dans les restes de supernova, et sont formés via diverses instabilités plasmas dépendant essentiellement de la vitesse et de la magnétisation des flux de plasmas. La description de tels chocs nécessite une approche cinétique, tant analytique que numérique.Dans cette thèse, nous avons étudié, au travers de simulations Particle-In-Cell (PIC), les processus sous-jacents par lesquels les instabilités rentrent en compétition les unes avec les autres. Nous avons montré que la diminution du rapport des masses entre ions et électrons, souvent utilisée en simulations numériques pour accélérer la dynamique des chocs, peut avoir de fortes conséquences sur le transfert d'énergie entre particules durant la phase non-linéaire des instabilités.Ces dernières, comme l'instabilité acoustique ionique (IAI) amènent sous certaines conditions à la formation de chocs électrostatiques, pouvant donner naissance à la formation de trous dans l'espace des phases, se propageant dans la région aval du choc, et accélérant ce dernier. L'ajout d'un champ magnétique externe conduit à un changement de médiation du choc, pouvant varier entre l'IAI et les ondes magnéto-soniques lente ou rapide en fonction de l'obliquité entre le champ magnétique et la normale au choc. De plus, nous avons montré que l'orientation du champ magnétique permet de choisir entre une dispersion convexe ou concave des ondes plasma conduisant à la création d'ondes précurseurs dans les régions amont ou aval du choc.Ces chocs magnétisés se trouvent être correctement représentés par le modèle magnétohydrodynamique (MHD) tant qu'ils restent laminaire et que leur potentiel dans la région aval n'est pas suffisamment grand pour réfléchir les particules du milieu amont.Nous avons montré que même pour des chocs sous critiques, une fraction d'ions réfléchis, ne pouvant pas être représentés par la MHD, est suffisante à la croissance d'ondes solitaires en amont du choc, conduisant à l’accélération de ce dernier, mais pas à un processus d'auto-reformation comme pour les chocs super critiques.Bien que les échelles spatio-temporelles soient très différentes, les lois d'échelle rendent possible l'étude de tels phénomènes en laboratoire. Nos études numériques ont été faites dans un cadre de type tube à choc pouvant être testé expérimentalement.A ce titre, nous proposons dans cette thèse une expérience sur la création d'îlots magnétiques, formés par l’interaction de plasmas générés par l'irradiation de cibles par laser baignant dans un champ magnétique externe, et conduisant à la formation de tels chocs.Enfin, nous avons démontré expérimentalement et numériquement la formation de chocs électromagnétiques sans collisions par le biais de l'instabilité de Weibel stimulée par l'instabilité de batterie Biermann, conduisant à l'accélération de particules par le mécanisme de Fermi. Ce nouveau type d'expérience pourrait expliquer l'origine du rayonnement cosmique provenant des restes de supernova
Collisionless shocks are ubiquitous in the Universe, especially in the supernova remnants, and are formed via various plasma instabilities mainly depending on the speed and magnetization of plasma flows. The description of such shocks requires a kinetic approach, both analytical and numerical.In this thesis, we have studied, through Particle-In-Cell (PIC) simulations, the underlying processes by which instabilities compete with each other.We have shown that the reduction of the ion-to-electron mass ratio, often used in numerical simulations to accelerate the dynamics of shocks, can have strong consequences on the energy transfer between particles during the non-linear phase of instabilities.These instabilities, like the ionic acoustic instability (IAI) lead under certain conditions to the formation of electrostatic shocks, which can give rise to phase space holes formation, propagating in the downstream shock region, and accelerating the shock.The addition of an external magnetic field leads to different shock mediation, which can vary between the IAI to the slow or fast magneto-sonic waves as a function of the obliquity between the magnetic field and the shock normal.Furthermore, we have shown that the orientation of the magnetic field makes it possible to choose between a convex or concave dispersion of the plasma waves leading to the creation of precursor waves in the upstream or downstream shock regions.These magnetized shocks are correctly represented by the magnetohydrodynamic (MHD) model as long as they remain laminar and their potential in the downstream region is not large enough to reflect the particles of the upstream medium.We have shown that even for sub-critical shocks, a fraction of reflected ions, which cannot be modeled by the MHD, is sufficient for the growth of solitary waves upstream of the shock, leading to the acceleration of the latter, but not to a process of 'self-reformation' as for super-critical shocks.Although spatio-temporal scales are very different, scaling laws make possible the study of such phenomena in the laboratory. Our numerical studies have been done in the context of shock tubes that can be experimentally tested.As such, we propose in this thesis an experiment on the creation of magnetic islands, formed by the interaction of plasmas generated by the irradiation of laser targets bathed in an external magnetic field, leading to the formation of such shocks.Finally, we experimentally and numerically demonstrated the formation of collisionless electromagnetic shocks through the Weibel instability stimulated by theBiermann Battery instability, and leading to particle acceleration by the Fermi mechanism.This new type of experiment could explain the origin of cosmic radiation from supernova remnants
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16

Mullan, James Vincent. "Applications of relativistic and non-relativistic classical and quantum mechanics to heavy-particle collisions." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337023.

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17

Fassari, Silvestro. "Spectral properties of relativistic and non-relativistic Krönig- Penney Hamiltonians with short-range impurities." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54524.

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In this work, we investigate the spectrum of the non-relativistic Krönig-Penney Hamiltonian Hα= -d²/dx² +αΣm∈Zδ(-(2m+1)π) perturbed by a short-range potential λW and the spectrum of its relativistic counterpart obtained by replacing the Schrödinger Hamiltonian Hα with its relativistic analogue H̅α. The interesting feature of both spectra is that they have gaps and that bound states may occur in such gaps as a consequence of the presence of the short-range potential representing the impurity. Such bound states, often called "impurity states" in the solid state physics literature. are important with regard to the conductivity properties of solids We show the existence of such bound states of Hα + λW in each sufficiently remote gap of its essential spectrum if the integral of W is different from zero and the 1 + 𝛅-moment of W is finite for some 𝛅 > 0. Furthermore, if the potential has a constant sign we prove that there is only one bound state in each sufficiently remote gap. We shall see that in the relativistic case one may have more than one bound state in each remote gap under the same assumptions on W. Nevertheless, we shall see that such additional bound states cannot appear in the range of energies of solid state physics.
Ph. D.
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Rubiera, García Diego. "Relativistic lagrangian non-linear field theories supporting non-topological soliton solutions." Doctoral thesis, Universidad de Oviedo, 2008. http://hdl.handle.net/10803/11131.

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En el contexto de la teoría de campos el interés en soluciones extendidas describiendo campos asociados a partículas puntuales data de los años 30, con los intentos de Born e Infeld para construir una electrodinámica no-lineal cuyas soluciones electrostáticas a simetría esférica eliminaran la divergencia de la autoenergía del electrón en Electrodinámica Clásica.En esta tesis realizamos un amplio estudio de una extensa clase de teorías relativistas de campos que contienen soluciones de tipo solitón no-topológico en tres dimensiones espaciales. Específicamente estudiamos campos (multi) escalares que surgen en teorías cuyos lagrangianos están definidos como funciones generales del término cinético habitual, y campos de gauge (abelianos y no-abelianos) en teorías gauge generalizadas con lagrangianos funciones de los dos invariantes cuadráticos del campo habituales. En el caso escalar hemos obtenido una completa caracterización de las soluciones estáticas a simetría esférica con energía finita, definida positiva, y que además son estables. Para el caso gauge se ha realizado un estudio general que conduce también en este caso a un completa caracterización de las soluciones electrostáticas a simetría esférica cuyas formas y energías pueden ponerse en relación con sus contrapartidas (multi) escalares. En todo este estudio la condición de "admisibilidad", que corresponde a la imposición de una serie de restricciones para obtener teorías físicamente admisibles, lleva una descripción exhaustiva de esta clase de teorías no-lineales.A partir de principios variacionales sobre la energía y del estudio de la evolución dinámica de las perturbaciones de estas soluciones en las ecuaciones de campos se han obtenido condiciones necesarias y suficientes para que estas soluciones (multi) escalares y gauge sean estables en el sentido "débil", es decir, frente a pequeñas perturbaciones que conserven la carga de cada campo. Asimismo, se introducen ejemplos explícitos de lagrangianos que pueden tener interesantes consecuencias fenomenológicas en varias áreas. Dichos lagrangianos se han estudiado con detalle, obteniendo una completa descripción de sus energías y otras propiedades físicamente relevantes. Un ejemplo particular de esta clase de modelos sería la teoría de Born-Infeld. Finalmente se han estudiado las aplicaciones que dichos lagrangianos con soluciones solitón no-topológico pueden tener en diversos ámbitos, tales como los lagrangianos efectivos en Electrodinámica Cuántica, o la descripción de la estructura interna de los hadrones.
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19

Hall, II Zack B. "General Relativistic Non-Radial Oscillations in Compact Stars." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10604673.

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Currently, we lack a means of identifying the type of matter at the core of compact stars, but in the future, we may be able to use gravitational wave signals produced by fluid oscillations inside compact stars to discover new phases of dense matter. To this end, we study the fluid perturbations inside compact stars such as Neutron Stars (NS) and Strange Quark Stars (SQS), focusing on modes that couple to gravitational waves (GWs). Using a modern equation of state for quark matter that incorporates interactions at moderately high densities, we implement an efficient computational scheme to solve the oscillation equations in the framework of General Relativity, and determine the complex eigenfrequencies that describe the oscillation and damping of the non-radial fluid modes. We find that the f- mode frequency only weakly distinguishes NS from SQS. However, we do find that the p- mode has a strong discriminating signature between the two models. In addition we study the impact of parameters of the SQS equation of state on the oscillation spectra. Finally, we discuss the significance of our results for future detection of these modes through gravitational waves.

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20

Rampf, Cornelius [Verfasser]. "(Non-)relativistic Lagrangian perturbation theory / Cornelius Stefan Rampf." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1037935993/34.

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21

Zebarjad, Seyyed Mohammad. "Positronium hyperfine splitting corrections using non-relativistic QED." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35425.

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We use Nonrelativistic Quantum Electrodynamics (NRQED) as an effective field theory to calculate the single photon annihilation contribution to the positronium hyperfine splitting (HFS) in its ground state at order Oa6 . Our analytical result completes the hyperfine splitting calculation to order mea6 . Using NRQED, we derive the Lamb shift of a scalar-scalar bound state and Oa5 hyperfine splitting of positronium for a general excited state. Using the same technique, we also rederive the Lamb shift of Hydrogen atom and Oa5 HFS of positronium in its ground state.
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22

Marzolla, Andrea. "Symmetry breaking and Goldstone bosons in holographic strongly coupled field theories: Relativistic and non-relativistic examples." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258338.

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In this thesis various holographic models are treated, which describe theories of fields where an internal symmetry is broken, either in relativistic contexts, or in case of violation of the Lorentz invariance.The first chapter opens with the revision of the notion of symmetry breaking in pure relativistic field theory. The case of spontaneous breaking and the Goldstone theorem are discussed, as well as the case of explicit breaking, where precise Ward identities between conserved current correlators and scalar operators loaded under such current are derived in a completely general way.We then consider two examples of non-relativistic field theories, which will be reproduced by holographic models: a model in which the invariance of boosts is broken by the presence of a chemical potential, and a model of Lifshitz's invariant theory. We show the non-relativistic realization of Ward's identities for the symmetry breaking.In the second chapter we briefly introduce the correspondence gravitation / gauge theory and we revise the central tool of this thesis, the holographic renormalization.In the third chapter, we show how to generate field theories with symmetry breaking by coupling a scalar field to a gauge field, and holographically deriving the Ward identities predicted by the field theory arguments, first in the Relativistic case. We also obtain an analytic expression for the scalar two-point function, where we know how to find the massless boson of Goldstone and the mass of linear mass in the explicit breaking parameter Of the Goldstone pseudo-boson, respectively in the purely spontaneous case and in the case of an explicit small break.We also consider the two-dimensional case on the edge, where we find that Coleman's theorem is eluded in the wide limit of $ N $, and Ward's identities are not affected.For non-relativistic cases, we first consider a non-abelian model in which the Lorentz invariance is broken: this situation makes it possible to observe so-called ~ B bosons which exhibit a quadratic dispersion relation and do not respect Not the law of a single Goldstone mode for each broken generator.Finally, we study in detail the holographic renormalization and the two-point functions for a conserved current and various scalar operators in a space-time of Lifshitz. We also find the Ward identities of symmetry breaking in their non-relativistic realization.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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23

Hiscox, Aaron. "Analysis of Regge poles in non-relativistic quantum mechanics." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/54238/.

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Regge poles—the name given to poles of the scattering amplitude in the complex angular momentum plane—are of utmost importance in atomic and molecular scattering. We investigate various aspects of non-relativistic Regge pole theory, namely, their behaviour at low energy, cardinality, and sensitivity to boundary conditions. upon investigation of the former, we find the long-standing conjecture that Regge poles become stable bound states for ultra low energy to be true; the proof is achieved for a potential satisfying the first moment condition at infinity and whose product with the radial variable is bounded near the origin, with the proviso that singular behaviour of the Regge poles may occur. It is known that for an analytic potential V with r2|V(r)| bounded at the origin and at infinity, there are finitely many Regge poles; we demonstrate that this is still the case for a compactly supported potential which is not as singular as the Coulomb interaction at the origin. This begs the question of whether or not it is possible to explicitly count Regge poles. Not only is this a difficult and interesting mathematical problem, but it also has implications in atomic physics where total cross-sections are often calculated using summations over Regge pole contributions. The author’s attempt at counting Regge poles has revealed an unexpected effect on the Regge poles due to boundary conditions: we show that infinitely many Regge poles go to infinity under nothing more than a change of boundary condition, at least for the free particle case.
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24

Varju, Katalin. "Quantum tests for non-inertial and general relativistic effects." Thesis, University of Kent, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322831.

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25

Ouellette, Stephen M. "SU(3) chiral symmetry in non-relativistic field theory." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-08172001-054126.

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26

Heissler, Patrick. "Relativistic laser plasma interaction." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-146019.

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27

Devlin, Francis Robert. "Physics of heavy quarks." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319786.

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28

Shakespeare, Norman Harold. "Simulations of non-relativistic quantum chromodynamics at strong and weak coupling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ61678.pdf.

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29

Breuer, John. "Dielectric laser acceleration of non-relativistic electrons at a photonic structure." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-161479.

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In dieser Arbeit berichten wir über die Beobachtung der dielektrischen Laserbeschleunigung nichtrelativistischer Elektronen mithilfe des inversen Smith-Purcell Effekts bei optischen Wellenlängen. Wenn die Phasengeschwindigkeit von evaneszenten Wellen nahe periodischer Gitterstrukturen mit der Elektronengeschwindigkeit übereinstimmt, kann eine vorwärtsgerichtete elektrische Feldkomponente das Elektron kontinuierlich beschleunigen. Dieser Effekt tritt jedoch nur im Nahfeld passender photonischer Strukturen auf, d.h., dass der Elektronenstrahl die Struktur in Abständen, die kleiner als die Wellenlänge sind, passieren muss. Für die Beschleunigung nichtrelativistischer 28keV Elektronen verwenden wir die dritte Raumharmonische eines Quarzgitters, die mittels Lichtpulsen eines Titan-Saphir-Oszillators angeregt wird. Wir messen einen maximalen Energiegewinn von 280eV, was einem Beschleunigungsgradienten von 25MeV/m entspricht. Dieser Wert ist vergleichbar mit dem Gradienten heutiger Radiofrequenz-Linearbeschleuniger. Um diese Beschleunigung zu erfahren, passieren die Elektronen die Gitteroberfläche in einem Abstand von weniger als 100nm. Im Rahmen dieser Arbeit beschreiben wir die Theorie der Elektronenbeschleunigung im Nahfeld von Gitterstrukturen und diskutieren Simulationsergebnisse zu dieser dielektrischen Laserbeschleunigung. Unsere Messergebnisse stimmen sehr gut mit den Simulationen überein und bestätigen deshalb die direkte Beschleunigung im Lichtfeld. Zusätzlich diskutieren wir die Elektronenbeschleunigung in Doppelgitterstrukturen, das Dephasieren nichtrelativistischer Elektronen, sowie den Raumladungseffekt, der den Spitzenstrahlstrom in diesen neuartigen, auf Mikrostrukturen basierenden Beschleunigern begrenzt. Die hier verwendeten photonischen Gitterstrukturen können direkt aneinandergereiht werden und erfüllen damit die Voraussetzung für skalierbare Linearbeschleuniger. Außerdem sind unsere Strukturen kompatibel mit den Mikrostrukturen, an denen die dielektrische Laserbeschleunigung relativistischer Elektronen zeitgleich durch unsere Kollegen in Stanford demonstriert wurde. Das Potenzial dielektrischer Laserbeschleuniger liegt in dem bis zu zwei Größenordnungen höheren Beschleunigungsgradienten verglichen mit konventionellen Beschleunigereinrichtungen, was sich letztendlich auf die größere Zerstörschwelle dielektrischer Materialien bei optischen Wellenlängen im Vergleich zu Metallen im Radio- und Mikrowellenbereich zurückführen lässt, die eine erhöhte Oberflächenspannungsfestigkeit zur Folge hat. Dieser erhöhte Beschleunigungsgradient könnte den Bau von deutlich kompakteren und kostengünstigeren Beschleunigern erlauben. Wir geben einen Ausblick auf den möglichen Aufbau solcher zukünftiger optischen Beschleuniger und auf deren potentiellen Anwendungen in kompakten Freie-Elektronen-Lasern.
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28keV electrons. We measure a maximum energy gain of 280eV, corresponding to an acceleration gradient of 25MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in Stanford. The potential of dielectric laser accelerators lies in the larger attainable acceleration gradients resulting in a more compact design as well as a lower cost of these devices compared with conventional accelerator facilities. This size reduction by potentially a factor of 100 is owed to the two orders of magnitude larger damage threshold of dielectric materials as compared to metals. We present an outlook towards the design of an envisioned large-scale dielectric laser accelerator and its possible application in future compact free electron lasers.
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30

Tanimu, Abdullahi. "Resonant state expansion for non-relativistic quantum mechanics in one dimension." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/114238/.

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This thesis presents my work that I have done together with my supervisor, Dr Egor Muljarov. It is based on the resonant state expansion (RSE), a rigorous perturbation theory, recently developed in electrodynamics. Here, the RSE is applied to non-relativistic quantum mechanical systems in one dimension. To facilitate the analytics, the model of Dirac delta functions for describing quantum potentials was employed. The resonant states (RSs) of a symmetric double quantum well structure modeled by delta functions was first calculated. The full set of these RSs is investigated. This includes bound, anti-bound and normal resonant states which are all eigenstates solutions of Schrodingers equation with boundary conditions of outgoing waves. These RSs are then taken as an unperturbed basis state, for the quantum mechanical (QM) analogue of the RSE (QM-RSE). The transformation of the RSs and their transitions between different subgroups as well as the role of each subgroup in observables, such as the quantum transmission, is also analysed. The resonant state expansion is first verifed for a triple viii quantum well systems, showing convergence to the available analytic solution as the number of resonant states in the basis increases. The method is then applied to multiple quantum well and barrier structures, including finite periodic systems. Results are compared with the eigenstates in triple quantum wells and in- finite periodic potentials described by the famous Kronig-Penney model, revealing the nature of the resonant states in the studied systems.
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31

Stavro, Ivanovski. "Central Weighted Non-Oscillatory (CWENO) and Operator Splitting Schemes in Computational Astrophysics." Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/193.

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High-resolution shock-capturing schemes (HRSC) are known to be the most adequate and advanced technique used for numerical approximation to the solution of hyperbolic systems of conservation laws. Since most of the astrophysical phenomena can be described by means of system of (M)HD conservation equations, nding most accurate, computationally not expensive and robust numerical approaches for their solution is a task of great importance for numerical astrophysics. Based on the Central Weighted Non-Oscillatory (CWENO) reconstruction approach, which relies on the adaptive choice of the smoothest stencil for resolving strong shocks and discontinuities in central framework on staggered grid, we present a new algorithm for systems of conservation laws using the key idea of evolving the intermediate stages in the Runge Kutta time discretization in primitive variables . In this thesis, we introduce a new so-called conservative-primitive variables strategy (CPVS) by integrating the latter into the earlier proposed Central Runge Kutta schemes (Pareschi et al., 2005). The advantages of the new shock-capturing algorithm with respect to the state-of-the-art HRSC schemes used in astrophysics like upwind Godunov-type schemes can be summarized as follows: (i) Riemann-solver-free central approach; (ii) favoring dissipation (especially needed for multidimensional applications in astrophysics) owing to the di ffusivity coming from the design of the scheme; (iii) high accuracy and speed of the method. The latter stems from the fact that the advancing in time in the predictor step does not need inversion between the primitive and conservative variables and is essential in applications where the conservative variables are neither trivial to compute nor to invert in the set of primitive ones as it is in relativistic hydrodynamics. The main objective of the research adopted in the thesis is to outline the promising application of the CWENO (with CPVS) in the problems of the computational astrophysics. We tested the method for one dimensional Euler hydrodynamics equations and we assessed the advantages against the operator splitting and finite-volume Godunov-type approaches implemented in the widely used astrophysical codes ZEUSMP/ 2 (Stone and Norman, 1992) and ATHENA (Stone et al., 2008), respectively. We extended the application of the scheme to one dimensional relativistic hydrodynamics (RHD), which (to the author's knowledge) is the fi rst successful attempt to approximate the special relativistic hydrodynamics with CWENO method. We demonstrate that strong discontinuities can be captured within two numerical zones and prevent the onset of numerical oscillations. In the second part of the present thesis, the astrophysical operator-splitting MHD code ZEUS-MP/2 has been used to perform three dimensional nonlinear simulations of MHD instabilities. First, we present global 3D nonlinear simulations of the Tayler instability in the presence of vertical elds. The initial con guration is in equilibrium, which is achieved by balancing a pressure gradient with the Lorentz force. The nonlinear evolution of the system leads to stable equilibrium with current free toroidal eld. We nd that the presence of a vertical poloidal eld stabilizes the system in the range from B phi approximately of order of Bz to higher values of Bz (Ivanovski and Bonanno, 2009). Second, the dynamics of the expansion of two colliding plasma plumes in ambient gas has been investigated via hydrodynamical simulations. Experimental observations of a single plume, generated by high power pulsed laser ablation of a solid target in ambient gas with pressure of about 10^-1 Torr, show possible Rayleigh-Taylor (RT) instability. Our numerical simulations with two plumes show RT instability even in low pressure gas, where single-plume expansion cannot cause instability. In addition, we nd that the RT instability is developed for about ten nanoseconds, while the instability in the case of a single plume typically takes thousand of nanoseconds. We show that the theoretically derived density condition for stability, Rho_plume < Rho_gas, is satis ed in all our simulations (Ivanovski et al., 2010). In the present thesis, we con rm the promising behavior of the conservative-primitive variables strategy with CWENO approach in computational astrophysics. We demonstrated high accuracy and robustness of the method in the essential one dimensional applications, sod-shock tubes and slow-moving shocks. Extending the method to higher dimensions and using the knowledge accumulated by means of direct numerical operator splitting simulations of MHD instabilities motivates building a modern accurate astrophysical code which will be able to resolve a wide range of problems, from ideal (magneto)hydrodynamics to relativistic (magneto)hydrodynamics.
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32

Hakl, Michael. "Infrared magneto-spectroscopy of relativistic-like electrons in three-dimensional solids." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY085/document.

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L'utilisation de l'équation de Dirac/Weyl conduit à une simplification conceptuelle dans une description de la structure de la bande dans les solides à faible échelle d'énergie. En particulier, les excitations d'électrons-trous peuvent être considérées comme analogues au cas relativiste tel que conductivité optique linéaire, le suppression de backscattering ou la manifestation des arcs de Fermi et la chiralité des particules. En outre, la phase semi-métallique est également un élément crucial pour la classification des matériaux. La taille de le gap est affectée qualitativement par le type de dispersion d'énergie par un croisement continu des bandes linéaires à paraboliques. Cela peut être compris comme une limite classique ou ultra-relativiste du mouvement d'une particule massive.La spectroscopie infrarouge de la transformation de Fourier est une technique unique pour étudier les excitations optiques dans une large gamme d'énergies et représente en combinaison avec le champ magnétique élevé un outil puissant pour sondage de la structure électronique et surmonte le principal obstacle des systèmes sans gap qui est un dopage fort en raison de désordre structurel.La première partie du travail est consacrée à l'arséniure de cadmium, où nous élaborons une approche de distinction qualitative entre les systèmes Dirac et Kane qui ont été utilisés pour prouver sur la base de la réponse magnéto-optique observée la réalisation du modèle Kane presque sans gap avec une similitude frappante avec HgCdTe, en contradiction avec l'existence de cônes purement Dirac. La magnéto-réflectivité dans un champ magnétique à champ élevé la résonance cyclotron caractéristiques par un radical-B dépendance avec un comportement particulier dans la limite quantique. En revanche, la magnéto-transmission montrait des transitions de niveau Landau qui doit être interprétées que comme un type plat-à-cône afin de préserver une cohérence totale du modèle. Les cônes de Dirac prédits par la théorie sont susceptibles de coexister dans le modèle de Kane sous la forme d'une sous-structure décrite par le modèle de Bodnar qui se rapproche de la structure cristalline complexe par une simple cellule antifluorite qui permet d'utiliser la théorie du k.p classique.Dans la deuxième partie, nous nous concentrons sur le bismuth comme isolant topologique 3D archétype. Nous étudions une condition particulière obéie pour le BHZ-hamiltonien qui apporte des propriétés intriguantes comme une relation inhabituelle de spin gap et la résonance du cyclotron, l'épinglage spécifique entre les fancharts des sous-groupes Landau ou les g-facteurs compensés dans les bandes de conduction et de valence. Les mesures de photoluminescence ont montré une émission directgap, ce qui donne un nouvel aperçu de la structure largement acceptée à partir des données ARPES, où la “chameau structure” de la bande de valence doit être expliquée dans le confinement de surface et le point de Dirac de l'état de surface doit être repositionné par rapport aux bandes en bulk. La réponse magnéto-optique peut être pleinement expliquée dans une image classique du paramagnétisme de Pauli comme un simple effet d'occupation. Un tel comportement se manifeste dans la transmission en tant que fractionnement progressif du bord d'absorption interbande avec une saturation successive due à la polarisation spin partielle ou totale des électrons. Le dichroïsme relatif entraîne également une forte rotation de Faraday linéaire décrite par un modèle simple de la constante Verdet qui ne dépend pas sur le niveau de Fermi
The use of the Dirac/Weyl equation leads to a conceptual simplification in a description of the band structure in solids at low energy scales. In particular, electron-hole excitations can be regarded as an analogue to the relativistic case with several expected phenomena to be observed in the condensed systems such as a suppressed back-scattering, linear optical conductivity or the manifestation of the Fermi arcs and particle's chirality. Moreover, the semimetallic phase also symbolizes a boundary between the trivial and topological insulators and thus play a crucial role for the material classification. The size of the gap qualitatively affects the type of the energy dispersion by a continuous crossover from the linear to parabolic bands. This fact can be easily understood as a classical or ultra-relativistic limit of the motion of a free massive particle.Infrared Fourier transform spectroscopy is a unique technique for studying optical excitations in a wide range of energies and it represents in combination with the high magnetic field a powerful tool for probing electronic structure and overcomes the main obstacle of the gapless systems that is a strong doping due to the structural disorder.The first part of the work is devoted to cadmium arsenide, where we elaborate an approach to qualitatively distinguish between the Dirac and Kane systems that was used to prove on the basis of the observed magneto-optical response the realization of the nearly gapless Kane model with a striking similarity to HgCdTe, contradicting the existence of purely Dirac cones. The magneto-reflectivity revealed a strong splitting of the plasma edge that turns into the cyclotron resonance characteristic by a squareroot-of-B dependence in the high magnetic field with a particular behaviour in the quantum limit independent on the initial Fermi level. In contrast, the magneto-transmission revealed interband Landau level transitions that could be only interpreted as a flat-to-cone type in order to preserve a full consistency of the model. The Dirac cones predicted by theory are feasible to coexist within the Kane model in the form of a substructure described by the Bodnar model that approximates the complex crystal structure by a simple antifluorite cell, which allows to use the conventional k.p-theory.In the second part, we focus on bismuth selenide entitled as an archetypal 3D topological insulator. We study a peculiar condition fulfilled for the BHZ-hamiltonian that brings intriguing properties such as an unusual relation of the spin gap and cyclotron resonance, the specific pinning between fancharts of Landau subsets or the compensated g-factors of the conduction and valence bands. The photoluminescence measurements showed a direct-gap emission, that gives a new insight to the widely accepted structure from ARPES data, where the declared camel-back structure of the valence band needs to be explained within the surface confinement and the Dirac point of the surface state should be repositioned with respect to the bulk bands. The magneto-optical response can be fully explained in a classical picture of the Pauli paramagnetism as a purely occupational effect. Such behaviour is evinced in the transmission as a gradual splitting of the interband absorption edge with a successive saturation due to the partial or total spin polarization of electrons. The related dichroism drives also a strong linear Faraday rotation described by a simple model of the Verdet constant that depends only on the Fermi level
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33

Moreno, Torres Daniel. "Non-relativistic bound states in QCD: towards the N3LL heavy quarkonium spectrum." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667376.

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34

Peach, Alexander Matthew. "Exploring the AdS/CFT correspondence : non-relativistic generalisations & holographic multiboundary wormholes." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12184/.

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In this thesis I explore two pertinent avenues of the $AdS/CFT$ correspondence: the rich, pragmatic context of non-relatavistic holography and the story of holographic multiboundary wormholes and their relation to the profound interplay between bulk geometry and boundary entanglement. In chapter \ref{intro}, I introduce the $AdS/CFT$ correspondence and review the key ideas that motivate and underlie the work in subsequent chapters. In chapter \ref{schleq2} we consider the development of a holographic dictionary for asymptotically locally Schr{\"o}dinger spacetimes for $z < 2$ in a massive vector model in various spatial dimensions. We carry out a linearised analysis of bulk perturbations and identify the boundary data as sources and vevs for the dual stress-energy complex. We verify that a sensible asymptotic expansion of bulk perturbations in sub-leading powers of $r$ exists by expanding them in eigenvalues of the boundary dilatation operator. The third chapter extends the work of the Chapter \ref{schleq2} to the case with $z=2$ in the massive vector model, in various dimensions, where the additional lightlike direction is regarded as internal from the boundary point of view, qualitatively unlike the $z<2$ case. Chapter \ref{hot} considers the entanglement structure of states holographically dual to multiboundary wormholes in the high-temperature limit, in which the thermal scale associated to each boundary is much larger than the $AdS$ scale. We find that the entanglement structure in this limit is almost entirely bipartite in this regime. The fifth chapter investigates the extent to which the results of chapter \ref{hot} generalise to regions of small moduli. We utilise heuristic tensor network methods to construct tensor network models of multiboundary wormhole states built by sewing tensors to Coxeter tilings and their quotients. We find in several cases that we can construct holographic states representing multiboundary wormhole geometries for which the entanglement structure is mostly, or almost entirely bipartite.
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35

Jaroschek, Claus. "Critical Kinetic Plasma Processes In Relativistic Astrophysics." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-46601.

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36

Canova, Lorenzo. "Generation and shaping of ultra-short, ultra-high contrast pulses for high repetition rate relativistic optics." Phd thesis, Ecole Polytechnique X, 2009. http://pastel.archives-ouvertes.fr/pastel-00005764.

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37

Leonardi, Andrea. "La visualizzabilità dei processi fisici: dalla meccanica quantistica non relativistica alla gravità quantistica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23939/.

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Per la fisica classica, la visualizzabilità era un aspetto implicito e scontato della teoria, un approccio intuitivo e naturale allo studio dei fenomeni. Nei primi del ‘900, l’esplicitazione della visualizzabilità entrava in contrasto con i nuovi risultati teorici e sperimentali portando Heisenberg a proporre una rivoluzione epistemologica: la fisica microscopica non può e non deve essere visualizzabile. A partire dal termine della Seconda guerra mondiale, le redini della fisica teorica passavano ai fisici statunitensi e il loro approccio epistemologicamente più morbido ripropone la visualizzabilità dei fenomeni fisici come una caratteristica soggettiva e intersoggettiva degli stessi fisici, riscontrabile nel successo dei diagrammi di Feynman. Il ventesimo secolo si chiude con l’impressione che la visualizzabilità stia invece scomparendo a favore di una visione del mondo priva di quei filtri mentali che, fin dall’antichità, furono ritenuti necessari per far sì che la nostra mente possa comprendere la realtà che ci circonda. Il terzo e ultimo capitolo, infine, propone un tentativo di visualizzazione dei fondamenti della teoria quantistica a partire dai legami matematici e formali della stessa con la meccanica classica.
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38

Bolaños, Puchet Marduk [Verfasser], and Klaus [Akademischer Betreuer] Hornberger. "Decoherence of non-relativistic bosonic quantum fields / Marduk Bolaños Puchet ; Betreuer: Klaus Hornberger." Duisburg, 2020. http://d-nb.info/1221061755/34.

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39

Pasquali, S. "LONG TIME DYNAMICS OF THE KLEIN-GORDON EQUATION IN THE NON-RELATIVISTIC LIMIT." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/487942.

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In this thesis I study the non-relativistic limit ($c \to \infty$) of the nonlinear Klein-Gordon (NLKG) equation on a manifold $M$, namely \[ \frac{1}{c^2} u_{tt} - \Delta u + c^2 u + \lambda |u|^{2(l-1)}u = 0, \; \; t \in \R, x \in M \] where $\lambda = \pm 1$, $l \geq 2$. The aim of the present work is to discuss the convergence of solutions of the NLKG to solutions of a suitable nonlinear Schr\"odinger (NLS) equation, and to study whether such convergence may hold for large (namely, of size$O(c^r)$ with $r \geq 1$) timescales. In particular I obtain the following results: (1) when $M$ is a general manifold, I show that the solution of NLS describes well the solution of the original equation up to times of order $\cO(1)$; (2) when $M=\mathbb{R}^d$,$d \geq 3$, I consider higher order approximations of NLKG and prove that small radiation solutions of the approximating equation describe well solutions of NLKG up to times of order $O(c^{2r})$ for any $r \geq 1$; (3) when $M=[0,\pi] \subset \mathbb{R}$ I consider the NLKG equation with aconvolution potential and prove existence for long times of solutionsin $H^s$ uniformly in $c$, which however has to belong to a set of large measure. I also get some new dispersive estimates for a Klein-Gordon type equation with a potential.
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40

Sargolzaei, Mahdi. "Orbital Polarization in Relativistic Density Functional Theory." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1167841057730-69007.

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The description of the magnetic properties of interacting many-particle systems has been one of the most important goals of physics. The problem is to derive the magnetic properties of such systems from quantum mechanical principles. It is well understood that the magnetization in an atom described by quantum numbers, spin (S), orbital (L), and total angular momentum (J) of its electrons. A set of guidelines, known as Hund's rules, discovered by Friedrich Hermann Hunds help us to determine the quantum numbers for the ground states of free atoms. The question ``to which extent are Hund's rules applicable on different systems such as molecules and solids?'' is still on the agenda. The main problem is that of finding the ground state of the considered system. Density functional theory (DFT) methods apparently are the most widely spread self-consistent methods to investigate the ground state properties. This is due to their high computational efficiency and very good accuracy. In the framework of DFT, usually the total energy is decomposed into kinetic energy, Coulomb energy, and a term called the exchange-correlation energy. Taking into account the relativistic kinetic energy leads to direct and indirect relativistic effects on the electronic structure of a solid. The most pronounced direct effect (although not the biggest in magnitude) is the spin-orbit splitting of band states. A well-known indirect relativistic effect is the change of screening of valence electrons from the nuclear charge by inner-shell electrons. One can ask that how relativistic effects come into play in ordinary density functional theory. Of course ordinary density functional theory does not include those effect. Four-current density functional theory (CDFT), the quantum electrodynamic version of the Hohenberg-Kohn theory is a powerful tool to treat relativistic effects. Although it is principally designed for systems in strong magnetic fields, CDFT can also be applied in situations where currents are present without external magnetic fields. As already pointed out by Rajagopal and Callaway (1973), the most natural way to incorporate magnetism into DFT is the generalization to CDFT. These authors, however, treated its most simple approximation, the spin density functional theory (SDFT), which keeps the spin current only and neglects completely correlation effects of orbital currents. By using the Kohn-Sham-Dirac (KSD) equation, spin-orbit coupling is introduced kinematically. The part of the orbital magnetism that is a consequence of Hund's second rule coupling is absent in this theory and there is not any more a one-to-one mapping of spin densities onto external fields. In solids, in particular in metals, the importance of Hund's second rule coupling (orbital polarization) and Hund's third rule (spin-orbit coupling) is usually interchanged in comparison to atoms. Thus, in applications of the relativistic CDFT to solids, the usual way has been to keep the spin-orbit coupling in the KSD equation (an extension to ordinary Kohn-Sham (KS) equation) and to neglect the orbital contribution to the total current density and approximate exchange-correlation energy functional with spin density only. This scheme includes a spontaneous exchange and correlation spin polarization. Orbital polarization, on the other hand, comes into play not as a correlation effect but also as an effect due to the interplay of spin polarization and spin-orbit coupling: In the presence of both couplings, time reversal symmetry is broken and a non-zero orbital current density may occur. Application of this scheme to 3d and 4f magnets yields orbital moments that are smaller than related experimental values by typically a factor of two. Orbital magnetism in a solid is strongly influenced by the ligand field, originating from the structural environment and geometry of the solid. The orbital moments in a solid with cubic symmetry are expected to be quenched if spin-orbit coupling is neglected. However, spin-orbit coupling induces orbital moments, accordingly. The relativistic nature of the spin-orbit coupling requires orbital magnetism to be treated within QED, and the treatment of QED in solids is possible in the frame of current density functional theory. The kinematic spin-orbit coupling is accounted for in many DFT calculations of magnetic systems within the LSDA. However, a strong deviation of the LSDA orbital moments from experiment is found in such approaches. To avoid such deviations, orbital polarization corrections would be desirable. In this Thesis, those corrections have been investigated in the framework of CDFT. After a short review for CDFT in Chapter 2, in Chapter 3, an &quot;ad hoc&quot; OP correction term (OPB) suggested by Brooks and Eriksson is given. This correction in some cases gives quite reasonable corrections to orbital moments of magnetic materials. Another OP correction (OPE), which has been introduced recently, was derived from the CDFT in the non-relativistic limit. Unfortunately, the program can only incompletely be carried through, as there are reasonable but uncontrolled approximations to be made in two steps of the derivation. Nevertheless, the result is quite close to the &quot;ad hoc&quot;ansatz. The calculated OPE energies for 3d and 4f free ions are in qualitative agreement with OPB energies. In Chapter 4, both corrections are implemented in the FPLO scheme to calculate orbital moments in solids. We found that both OPB and OPE corrections implemented in FPLO method, yield reasonably well the orbital magnetic moments of bcc Fe, hcp Co and fcc Ni compared with experiment. In Chapter 5, the effect of spin-orbit coupling and orbital polarization corrections on the spin and orbital magnetism of full-Heusler alloys is investigated by means of local spin density calculations. It is demonstrated, that OP corrections are needed to explain the experimental orbital moments. Model calculations employing one ligand field parameter yield the correct order of magnitude of the orbital moments, but do not account for its quantitative composition dependence. The spin-orbit coupling reduces the degree of spin polarization of the density of states at Fermi level by a few percent. We have shown that the orbital polarization corrections do not change significantly the spin polarization degree at the Fermi level. We also provide arguments that Co2FeSi might not be a half-metal as suggested by recent experiments. In Chapter 6, to understand recent XMCD data for Co impurities in gold, the electronic structure of Co impurities inside gold has been calculated in the framework of local spin density approximation. The orbital and spin magnetic moment have been evaluated. In agreement with experimental findings, the orbital moment is enhanced with respect to Co metal. On the other hand, internal relaxations are found to reduce the orbital moment considerably, whereas the spin moment is less affected. Both OPB and OPE yield a large orbital moment for Co impurities. However, those calculated orbital moments are almost by a factor of two larger than the experimental values. We also found that the orbital magnetic moment of Co may strongly depend on pressure.
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41

Zhang, Hongbin. "Relativistic Density Functional Treatment of Magnetic Anisotropy." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-25132.

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Spin-orbit coupling (SOC) reduces the spatial symmetry of ferromagnetic solids. That is, the physical properties of ferromagnetic materials are anisotropic, depending on the magnetization direction. In this thesis, by means of numerical calculations with full-relativistic density functional theory, we studied two kinds of physical properties: surface magnetic anisotropy energy (MAE) and anisotropic thermoelectric power due to Lifshitz transitions. After a short introduction to the full-relativistic density functional theory in Chapter 2, the MAE of ferromagnetic thin films is studied in Chapter 3. For such systems, separation of different contributions, such as bulk magnetocrystalline anisotropy (MCA) energy, shape anisotropy energy, and surface/interface anisotropy energy, is crucial to gain better understanding of experiments. By fitting our calculating results for thick slabs to a phenomenological model, reliable surface MAE could be obtained. Following this idea, we have studied the MAE of Co slabs with different geometries, focusing on the effects of orbital polarization correction (OPC). We found that the surface anisotropy is mainly determined by the geometry. While OPC gives better results of orbital moments, it overestimates the MAE. In the second part of Chapter3, the effects of electric fields on the MAE of L10 ferromagnetic thin films are studied. Using a simple model to simulate the electric field, our calculations are in good agreement with previous experimental results. We predicted that for CoPt, even larger effects exist. Moreover, we found that it is the amount of screening charge that determines the magnetoelectric coupling effects. This gives us some clue about how to achieve electric field control of magnetization direction. In Chapter 4, Lifshitz transitions in L10 FePt caused by a canted magnetic field are studied. We found several Lifshitz transitions in ordered FePt with tiny features in DOS. Using a two-band model, it is demonstrated that at such transitions, the singular behaviour of kinetic properties is due to the interband scattering, and the singularity itself is proportional to the derivative of the singular DOS. For FePt, such singularity will be smeared into anomaly by chemical disorder. Using CPA, we studied the effects of energy level broadening for the critical bands in FePt. We found that for experimentally available FePt thin films, Lifshitz transitions would induce up to a 3% increase of thermopower as the magnetization is rotated from the easy axis to the hard axis
Spin-Bahn-Kopplung reduziert die Symmetrie ferromagnetischer Festkörper. Das bedeutet, dass die physikalischen Eigenschaften ferromagnetischer Stoffe anisotrop bezüglich der Magnetisierungsrichtung sind. In dieser Dissertation werden mittels numerischer voll-relativistischer Dichtefunktional-Rechnungen zwei Arten physikalischer Eigenschaften untersucht: magnetische Oberflächen-Anisotropieenergie (MAE) und anisotrope Thermokraft durch Lifshitz-Übergänge. Nach einer kurzen Einführung in die relativistische Dichtefunktional-Theorie in Kapitel 2 wird in Kapitel 3 die MAE ferromagnetischer dünner Filme untersucht. In diesen Systemen ist es für ein Verständnis experimenteller Ergebnisse wichtig, verschiedene Beiträge zu separieren: Volumenanteil der magnetokristallinen Anisotropie (MCA), Formanistropie und Oberflächen bzw. Grenzflächenanisotropie. Durch Anpassen berechneter Daten für dicke Schichten an ein phänomenologisches Modell konnten verlässliche Oberflächen Anisotropien erhalten werden. In dieser Weise wurde die MAE von Co- Schichten mit unterschiedlichen Geometrien untersucht, wobei der Einfluss von Orbitalpolarisations-Korrekturen (OPC) im Vordergrund stand. Es wurde gefunden, dass die Oberflächenanisotropie hauptsächlich von der Geometrie bestimmt wird. Während OPC bessere Ergebnisse für die Orbitalmomente liefert, wird die MAE überschätzt. Im zweiten Teil von Kapitel 3 wird der Einfluss elektrischer Felder auf die MAE von dünnen ferromagnetischen Filmen mit L10-Struktur untersucht. Unter Verwendung eines einfachen Modells zur Simulation des elektrischen Feldes liefern die Rechnungen gute Übereinstimmung mit vorliegenden experimentellen Ergebnissen. Es wird vorhergesagt, dass für CoPt ein noch größerer Effekt existiert. Weiterhin wurde gefunden, dass die magnetoelektrische Kopplung von der Größe der Abschirmladung bestimmt wird. Dies ist eine wichtige Einsicht, um die Magnetisierungsrichtung durch ein elektrisches Feld kontrollieren zu können. In Kapitel 4 werden Lifshitz-Übergänge untersucht, die ein gekantetes Magnetfeld hervorruft. Es wurden mehrere Lifshitz-Übergänge in geordnetem FePt gefunden, welche kleine Anomalien in der Zustandsdichte hervorrufen. Mit Hilfe eines Zweiband-Modells wird gezeigt, dass an solchen Übergängen das singuläre Verhalten kinetischer Eigenschaften durch Interband- Streuung verursacht wird und dass die Singularität proportional zur Ableitung der singulären Zustandsdichte ist. In FePt wird durch chemische Unordnung diese Singularität zu einer Anomalie verschmiert. Der Einfluss einer Verbreiterung der Energieniveaus der kritischen Bänder in FePt wurde mittels CPA untersucht. Es wurde gefunden, dass in experimentell verfügbaren dünnen FePt-Filmen Lifshitz-Übergänge bis zu 3% Erhöhung der Thermokraft erzeugen, wenn die Magnetisierung von der leichten in die harte Richtung gedreht wird
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42

Dorkin, S. M., B. Kämpfer, L. P. Kaptari, and S. S. Semikh. "Relativistic Description of Exclusive Deuteron Break-up Reactions." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31290.

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The exclusive deuteron break-up reaction is analyzed within a covariant approach based on the Bethe-Salpeter equation with realistic meson-exchange interaction. Relativistic effects in the cross section, tensor analyzing power and polarization transfer are investigated in explicit form. Results of numerical calculations are presented for kinematical conditions in forthcoming p + D reactions at COSY.
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43

Jung, Daniel. "Ion acceleration from relativistic laser nano-target interaction." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-140744.

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44

Osterhoff, Jens. "Stable, ultra-relativistic electron beams by laser-wakefield acceleration." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-96539.

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45

Kiefer, Daniel. "Relativistic electron mirrors from high intensity laser nanofoil interactions." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-153796.

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46

Iqbal, Khalid. "Radiation effects on relativistic electrons in strong external fields." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-163156.

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47

Lefa, Eva [Verfasser], and Felix A. [Akademischer Betreuer] Aharonian. "Non-thermal Radiation Processes in Relativistic Outflows from AGN / Eva Lefa ; Betreuer: Felix A. Aharonian." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1180607813/34.

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48

Lehmann, Alexander [Verfasser], and Alexander [Akademischer Betreuer] Rothkopf. "Minkowskian Lattice Simulation for Non-Relativistic Quarks in Classical Fields / Alexander Lehmann ; Betreuer: Alexander Rothkopf." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1211820793/34.

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49

Kämpfer, Burkhard, S. M. Dorkin, S. S. Semikh, and L. P. Kaptari. "Elastic Proton-Deuteron Backward Scattering: Relativistic Effets and Polarization Observables." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-30980.

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The elastic proton-deuteron backward reaction is analyzed within a covariant approach based on the Bethe-Salpeter equation with realistic meson-exchange interaction. Lorentz boost and other relativistic effects in the cross section and spin correlation observables, like tensor analyzing power and polarization transfer etc., are investigated in explicit form. Results of numerical calculations for a compbte set of polarization observables are presented.
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50

Böhle, Frederik. "Near-single-cycle laser for driving relativistic plasma mirrors at kHz repetition rate - development and application." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX116/document.

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Les impulsions laser ultrabrèves nous permettent de suivre en temps réel les phénomènes ultrarapides au sein de la matière à l’échelle microscopique. C’est précisément pour l’invention de la chimie à l’échelle femtoseconde, ou femtochimie, qu’Ahmed Zewail se vit décerner le prix Nobel de chimie en 1999. Depuis les utilisateurs du laser cherchent à augmenter la résolution temporelle, c’est-à-dire réduire la durée des impulsions laser. Aujourd’hui, nous savons générer des flashs lumineux à l’échelle attoseconde dans le domaine spectral de l’extrême ultraviolet (XUV) mais l’efficacité de génération reste faible et le développement de sources laser attosecondes intenses constitue un sujet de recherche très actif sur le plan international.Notre groupe au LOA se concentre sur la génération d’impulsions attoseconde sur miroir plasma en régime relativiste. Pour cela, il cherche à développer une source d’impulsions femtosecondes à forte cadence et fort contraste et suffisamment énergétiques pour atteindre des intensités relativistes (>> 10^18W/cm2) lorsqu’elles sont fortement focalisées sur un plasma surdense. Un plasma surdense réfléchit la lumière incidente et par conséquent agit comme un miroir qui se déplaçant à vitesse relativiste et qui comprime l’impulsion incidente, produisant ainsi un flash attoseconde par cycle optique. En utilisant des impulsions proches d’un cycle optique, il est donc envisageable de générer une seule impulsion attoseconde intense pendant l’interaction.Dans la première partie de mon travail de thèse, j’ai réalisé un compresseur nonlinéaire pour réduire la durée des impulsions issues d’une chaîne à double dérive de fréquence (10mJ, 25fs, 1kHz) à phase enveloppe-porteuse (CEP) stabilisée. En propageant les impulsions du laser à haute intensité dans une fibre creuse remplie de gaz rare, j’ai réussi à générer des impulsions de 1.3 cycle optique avec une puissance crête autour de 1TW avec une CEP stabilisée. Dans un deuxième temps, j’ai mis en forme spatialement et temporellement les impulsions issues du compresseur à fibre pour générer à la fois des impulsions attosecondes intenses et des faisceaux d’électrons énergétiques sur un miroir plasma à gradient de densité contrôlé. Ces expériences nous permis, pour la première fois, de mettre en évidence la production d’impulsions attosecondes isolées dans l’XUV, l’émission corrélée de faisceaux d’électrons énergétiques en régime relativiste ainsi qu’un nouveau régime d’accélération d’électrons à très long gradient plasma
Very short light pulses allow us to resolve ultrafast processes in molecules, atoms and condensed matter. This started with the advent of Femtochemistry, for which Ahmed Zewail received the Novel Prize in Chemistry in 1999. Ever since, researcher have been trying to push the temporal resolution further and we have now reached attosecond pulse durations. Their generation, however, remains very challenging and various different generation mechanisms are the topic of heated research around the world.Our group focuses on attosecond pulse generation and ultrashort electron bunch acceleration on solid targets. In particular, this thesis deals with the upgrade of a high intensity, high contrast, kHz, femtosecond laser chain to reach the relativistic interaction regime on solid targets. Few cycle driving laser pulses should allow the generation of intense isolated attosecond pulses. A requirement to perform true attosecond pump-probe exeriments.To achive this, a HCF postcompression scheme has been conceived and implemented to shorten the duration of a traditional laser amplifier. With this a peak intensity of 1TW was achieved with near-single-cycle pulse duration. For controlled experiments, a vacuum beamline was developed and implemented to accurately control the laser and plasma conditions on target.During the second part of this thesis, this laser chain was put in action to drive relativistic harmonic generation on solid targets. It was the first time ever that this has been achieved at 1 kHz. By CEP gating the few-cycle-pulses, single attosecond pulses were generated. This conclusion has been supported by numerical simulations. Additionally a new regime to accelerate electron bunches on soft gradients has been detected
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