Browsing by Author "Restrepo, Juliana"

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    Ambientes virtuales colaborativos aplicados a la educación superior
    (1999) Trefftz Gómez, Helmuth; Trefftz, Christian; Correa, Carlos David; González, Miguel Ángel; Restrepo, Juliana; Cardona, Francisco; Imbeau, Gilles; Vélez, María Isabel; Universidad EAFIT.
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    Dynamics of entanglement and quantum discord in the Tavis-Cummings model
    (2016-05-20) Restrepo, Juliana; Rodríguez, Boris A.
    We revisit the problem of the dynamics of quantum correlations in the Tavis-Cummings model. Our results show that the dynamics of entanglement and quantum discord are far from being trivial or intuitive. We find states with the same entanglement but different discord and states where the two quantifiers give opposite information about correlations at a certain time. We furthermore show that many of the dynamical features of quantum discord attributed to dissipation are already present in the exact framework and are due to the characteristic quantum nonlinearity of the model and to the choice of initial conditions. Through a comprehensive analysis of pure and mixed initial conditions, we find a fascinating range of phenomena that can be used for experimental purposes. We propose an experiment called quantum discord gates where for given pure initial condition discord is zero or non-zero depending on the number of photons in the cavity. Given the marginal character of states with zero discord this result is not only completely counterintuitive but is also useful as a way to count photons.
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    Heat current characteristics in nanojunctions with superconducting baths
    (2014-08-11) Oettinger, David; Chitra, R.; Restrepo, Juliana
    As a fundamental requisite for thermotronics, controlling heat flow has been a longstanding quest in solid state physics. Recently, there has been a lot of interest in nanoscale hybrid systems as possible candidates for thermal devices. In this context, we study the heat current in the simplest hybrid device of a two level system weakly coupled to two heat baths. We use the reduced density matrix approach together with a simple Born-Markov approximation to calculate the heat current in the steady state. We consider different kinds of reservoirs and show that the nature of the reservoir plays a very important role in determining the thermal characteristics of the device. In particular, we investigate the effectiveness of a conventional superconductor as a reservoir with regard to manipulating the heat current. In the emergent temperature characteristics, we find that superconductivity in the reservoirs leads to enhanced thermal currents and that the superconducting phase transition is clearly visible in the heat current. We observe negative differential thermal conductance and a pronounced rectification of the heat current, making this 9 a good building block for a quantum thermal diode.
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    Heat Current Characteristics in Nanojunctions with Superconducting Leads
    (2014-02-12) Oettinger, David; Chitra, R.; Restrepo, Juliana
    Controlled heat flow has been a longstanding quest in solid state physics as this is a fundamental requisite for thermotronics. Recently, there has been a lot of interest in nanoscale hybrid systems as possible candidates for thermal devices. In this context, we study the heat current in the simplest hybrid device of a two level system weakly coupled to two heat baths. We use the reduced density matrix approach coupled with a simple Born-Markov approximation to calculate the heat current in the steady state. We consider different kinds of reservoirs and show that the nature of the reservoir plays a very important role in determining the thermal characteristics of the device. In particular, we investigate the effectiveness of a conventional superconductor as a reservoir with regard to manipulating the heat current. In the emergent temperature characteristics, we find that superconductivity in the reservoirs leads to enhanced thermal currents and that the superconducting phase transition is clearly visible in the heat current. We observe negative differential thermal conductance and a pronounced rectification of the heat current making this a good building block for a quantum thermal diode.