RT info:eu-repo/semantics/doctoralThesis
T1 Multipartite entanglement in harmonic oscillators subjected to dissipative quantum dynamics
A1 Valido Flores, Antonio Aljandro
A2 Universidad de La Laguna. Departamento de Física
K1 Física
AB A meaningful description of the low-energy dynamics of multipartite entanglement is providedfor harmonic oscillator systems in general dissipative scenarios. Without doing anycentral approximation, this mainly relies on a set of reasonable physical statements on theenvironment and system-environment interaction consistent with a linear analysis of theopen-system dynamics.We  rst investigate the inseparability properties of arbitrary entangled states, whichgenerally entails an optimization procedure of certain functional de ned in the in nitedimensionalHilbert space of continuous-variable systems. Using a Gaussian-like assumptionanalogous to that used in the derivation of Gaussian entanglement of formation, wederive a computational-e cient form of such functional which considerable simpli es theoptimization task. This consists on a hierarchy of separability criteria that permit in auni ed way to characterize k-partite entanglement of broad classes of Gaussian and non-Gaussian states. The strength of the criteria is proven by showing that they satisfactorilyreproduce previous results from the theory of entanglement, like PPT criterion applied toarbitrary two-mode and pure three-mode Gaussian states.The separability criteria allow to monitor the transient evolution of multipartite entanglementunder the environmental inuence, this permitted to show that non-Gaussianentanglement may be as robust against harmful dissipative e ects and thermal noise asGaussian one. We devote special attention to the stationary properties of tripartite entanglementwhen the system oscillators are in contact with either a common environmentor independent environments at initial di erent temperatures. For the former dissipativescheme, it is shown that the environment mediates an e ective many-party interaction witha spatial long-range feature between system oscillators, which is able to generate tripartiteentanglement whereas two-mode entanglement is degraded. Regarding the second scheme,it is illustrated that thermal non-equilibrium conditions result in a rich variety of quantumcorrelations, however a temperature gradient eventually destroys the entanglement sharedby the system oscillators as a consequence of the growth of thermal noise. Finally, thestationary entanglement and energy current across a  nite harmonic chain are studied indetail by doing an extensive numerical analysis of both phenomena for a broad range of theparameters (i.e., temperatures, oscillator frequencies, and oscillator coupling strengths).Our numerical  ndings are discussed in terms of the derived energy current expressions,these show an explicit dependence on the two-time correlation functions (between oscillatoroperators) which carry quantum correlations.
YR 2015
FD 2015
LK http://riull.ull.es/xmlui/handle/915/2275
UL http://riull.ull.es/xmlui/handle/915/2275
LA en
NO Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI)
DS Repositorio institucional de la Universidad de La Laguna
RD 18-nov-2024