Decoherencia en el transporte cuántico : descripciones dinámicas y procesos dependientes de espín

Tesis (Doctor en Física)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación, 2016.La pérdida de correlación de fase en un sistema cuántico es conocida como decoherencia y es consecuencia de las interacción con el ambiente. En esta tesis nos enfocamos en desarrollar herramientas teóricas y numéricas que permitan describir el efecto de la decoherencia en el transporte cuántico de sistemas con dependencia temporal o que presenten procesos de inversión de espín. En particular abordamos problemas de transporte a través de paredes de dominios magnéticos, magnetorresistencia gigante, dinámica cuántica decoherente y motores cuánticos. Los modelos y métodos desarrollados son los suficientemente generales como para ser aplicados en otras situaciones.The loss of phase correlation in a quantum system is known as decoherence and it is consequence of interactions with the environment. In this thesis, we focus on developing theoretical and numerical tools to describe the effect of decoherence in quantum transport of systems with time dependence or with spin-flipping processes. In particular we address the problems of transport through magnetic domain walls, giant magnetoresistance, decoherent quantum dynamics and adiabatic quantum motors. The models and methods developed in this thesis are general enough to be applied in other situations

Implementation of Optimal Thermal Radiation Pumps Using Adiabatically Modulated Photonic Cavities

We numerically implement the concept of thermal radiation pumps in realistic photonic circuits and demonstrate their efficiency to control the radiation current, emitted between two reservoirs with equal temperature. The proposed pumping scheme involves a cyclic adiabatic modulation of two parameters that control the spectral characteristics of the photonic circuit. We show that the resulting pumping cycle exhibits maximum radiation current when a cyclic modulation of the system is properly engineered to be in the proximity of a resonance degeneracy in the parameter space of the photonic circuit. A developed Floquet scattering framework, which in the adiabatic limit boils down to the analysis of an instantaneous scattering matrix, is offering an engineering tool for designing and predicting the performance of such thermal pumps. Our predictions are confirmed by time-domain simulations invoking an adiabatically driven photonic cavity.Fil: Fernández, Lucas Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Li, Huanan. City University of New York; Estados UnidosFil: Nafari, Mona. Wesleyan University; Estados UnidosFil: Kottos, Tsampikos. Wesleyan University; Estados Unido

Extreme Nonreciprocal Near-Field Thermal Radiation via Floquet Photonics

By using Floquet driving protocols and interlacing them with a judicious reservoir emission engineering, we achieve extreme nonreciprocal thermal radiation. We show that the latter is rooted in an interplay between a direct radiation process occurring due to temperature bias between two thermal baths and the modulation process that is responsible for pumped radiation heat. Our theoretical results are confirmed via time-domain simulations with photonic and rf circuits.Fil: Fernández, Lucas Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Kononchuk, Rodion. Ohio Wesleyan University.; Estados UnidosFil: Li, Huanan. City University of New York; Estados UnidosFil: Kottos, Tsampikos. Ohio Wesleyan University.; Estados Unido

Optical phase transitions in photonic networks: a spin-system formulation

We investigate the collective dynamics of nonlinearly interacting modes in multimode photonic settings. To this end, we have established a connection with the theory of spin networks. The emerging "photonic spins"are complex, soft (their size is not fixed), and their dynamics has two constants of motion. Our analysis sheds light on the nature of the thermal equilibrium states and reveals the existence of optical phase transitions which resemble a paramagnetic to a ferromagnetic and to a spin-glass phase transition occurring in spin networks. We show that, for fixed optical power, these transitions are driven by the type of the network connectivity, its coordination number, and the total energy of the optical signal. In strictly one-dimensional photonic networks we establish a universal one-parameter scaling that dictates the crossover from a (quasi)ferromagnetic phase to a paramagnetic phase.Fil: Ramos, Alba Yanina. Wesleyan University Middletown; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Fernández, Lucas Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; Argentina. Wesleyan University Middletown; Estados UnidosFil: Kottos, Tsampikos. Wesleyan University Middletown; Estados UnidosFil: Shapiro, Boris. Technion - Israel Institute of Technology; Israe

Nonequilibrium current-induced forces caused by quantum localization: Anderson adiabatic quantum motors

In recent years, there has been an increasing interest in nanomachines. Among them, current-driven ones deserve special attention as quantum effects can play a significant role there. Examples of the latter are the so-called adiabatic quantum motors. In this paper, we propose using Anderson's localization to induce nonequilibrium forces in adiabatic quantum motors. We study the nonequilibrium current-induced forces and the maximum efficiency of these nanomotors in terms of their respective probability distribution functions. Expressions for these distribution functions are obtained in two characteristic regimes: the steady-state and the short-time regimes. Even though both regimes have distinctive expressions for their efficiencies, we find that, under certain conditions, the probability distribution functions of their maximum efficiency are approximately the same. Finally, we provide a simple relation to estimate the minimal disorder strength that should ensure efficient nanomotors.Fil: Fernández, Lucas Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Pastawski, Horacio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Bustos Marun, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentin

Measurements of CP-conserving trilinear gauge boson couplings WWV (V ≡ γ,Z) in e+e− collisions at LEP2

The data taken by DELPHI at centre-of-mass energies between 189 and 209 GeV are used to place limits on the CP-conserving trilinear gauge boson couplings ΔgZ1 , λ γ and Δκ γ associated to W + W − and single W production at LEP2. Using data from the jj ℓ ν, jjjj, jjX and ℓ X final states, where j, ℓ and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero: ΔgZ1=−0.025+0.033−0.030,\vskip6ptλγ=0.002+0.035−0.035and\vskip6ptΔκγ=0.024+0.077−0.081. Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions of the Standard Model and supersede the previous results on these gauge coupling parameters published by DELPHI

Search for single top quark production via contact interactions at LEP2

Single top quark production via four-fermion contact interactions associated to flavour-changing neutral currents was searched for in data taken by the DELPHI detector at LEP2. The data were accumulated at centre-ofmass energies ranging from 189 to 209 GeV, with an integrated luminosity of 598.1 pb?1. No evidence for a signal was found. Limits on the energy scale ?, were set for scalar-, vector- and tensor-like coupling scenarios.We are greatly indebted to our technical collaborators, to the members of the CERN-SL Division for the excellent performance of the LEP collider, and to the funding agencies for their support in building and operating the DELPHI detector. We acknowledge in particular the support of Austrian Federal Ministry of Education, Science and Culture, GZ 616.364/2-III/2a/98, FNRS–FWO, Flanders Institute to encourage scientific and technological research in the industry (IWT) and Belgian Federal Office for Scientific, Technical and Cultural affairs (OSTC), Belgium, FINEP, CNPq, CAPES, FUJB and FAPERJ, Brazil, Ministry of Education of the Czech Republic, project LC527, Academy of Sciences of the Czech Republic, project AV0Z10100502, Commission of the European Communities (DG XII), Direction des Sciences de la Matiere, CEA, France, ` Bundesministerium fur Bildung, Wissenschaft, Forschung und Tech- ¨ nologie, Germany, General Secretariat for Research and Technology, Greece, National Science Foundation (NWO) and Foundation for Research on Matter (FOM), The Netherlands, Norwegian Research Council, State Committee for Scientific Research, Poland, SPUB-M/CERN/PO3/ DZ296/2000, SPUB-M/CERN/PO3/DZ297/2000, 2P03B 104 19 and 2P03B 69 23(2002-2004), FCT—Fundação para a Ciência e Tecnologia, Portugal, Vedecka grantova agentura MS SR, Slovakia, Nr. 95/5195/134, Ministry of Science and Technology of the Republic of Slovenia, CICYT, Spain, AEN99-0950 and AEN99-0761, The Swedish Research Council, The Science and Technology Facilities Council, UK, Department of Energy, USA, DE-FG02-01ER41155, EEC RTN contract HPRN-CT-00292-2002

A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole

The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly decaying b-hadrons, Eweak B . The average value of xweak B = Eweak B /Ebeam is measured to be 0.699 ± 0.011. The resulting xweak B distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of bhadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data: a = 1.84+0.23 ?0.21 and b = 0.642+0.073 ?0.063 GeV?2, with a correlation factor ? = 92.2%. Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of xweak B is found to be 0.7092 ± 0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained: a = 1.48+0.11 ?0.10 and b = 0.509+0.024 ?0.023 GeV?2, with a correlation factor ? = 92.6%

Search for heavy stable charged particles in pp collisions at ?s = 7 TeV

The result of a search at the LHC for heavy stable charged particles produced in pp collisions at s?=7TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb?1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398GeV/c 2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c 2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.We are grateful to Anna Kulesza and Michael Krämer for providing the theoretical production cross sections and associated uncertainties at next-to-leading order for pair production of eg and ˜t1. We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Search for a W'' boson decaying to a muon and a neutrino in pp collisions at vs=7 TeV

A new heavy gauge boson, , decaying to a muon and a neutrino, is searched for in pp collisions at a centre-of-mass energy of 7 TeV. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 36 pb?1. No significant excess of events above the standard model expectation is found in the transverse mass distribution of the muon?neutrino system. Masses below 1.40 TeV are excluded at the 95% confidence level for a sequential standard-model-like . The mass lower limit increases to 1.58 TeV when the present analysis is combined with the CMS result for the electron channel.We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)