Liliana Arrachea

Triplet superconductivity in quasi-one-dimensional systems

We study a Hubbard Hamiltonian, including a quite general nearest-neighbor interaction, parametrized by repulsion V, exchange interactions

Green-function approach to transport phenomena in quantum pumps

{J}_{z}{,J}_{\ensuremath{\perp}},

Heat production and energy balance in nanoscale engines driven by time-dependent fields

bond-charge interaction X, and hopping of pairs W. The case of correlated hopping, in which the hopping between nearest neighbors depends upon the occupation of the two sites involved, is also described by the model for sufficiently weak interactions. We study the model in one dimension with usual continuum-limit field theory techniques, and determine the phase diagram. For arbitrary filling, we find a very simple necessary condition for the existence of dominant triplet superconducting correlations at large distance in the spin SU(2) symmetric case:

Dynamical energy transfer in ac-driven quantum systems

4V+Jl0.

Anomalous flux quantization in a hubbard ring with correlated hopping.

In the correlated-hopping model, the three-body interaction should be negative for positive V. We also compare the predictions of this weak-coupling treatment with numerical exact results for the correlated-hopping model obtained by diagonalizing small chains and using a Berry phase to determine the opening of the spin gap.

Vibrational cooling and thermoelectric response of nanoelectromechanical systems

We present a general treatment to study transport phenomena in systems described by tight-binding Hamiltonians coupled to reservoirs and with one or more time-periodic potentials. We apply this treatment to the study of transport phenomena in a double barrier structure with one and two harmonic potentials. Among other properties, we discuss the origin of the sign of the net current.

Current-induced switching in transport through anisotropic magnetic molecules

We present a formalism to study the heat transport and the power developed by the local driving fields on a quantum system coupled to macroscopic reservoirs. We show that, quite generally, two important mechanisms can take place: (i) directed heat transport between reservoirs induced by the ac potentials, and (ii) at slow driving, two oscillating out of phase forces perform work against each other, while the energy dissipated into the reservoirs is negligible.

Adiabatic response and quantum thermoelectrics for ac driven quantum systems

This work was supported in part by MINECO Grants No. FIS2011-23526 and No. CSD2007-00042 (CPAN), the NSF under Grant No. NSF PHY11-25915, the UBACyT, CONICET, and MINCyT, Argentina.

Periodic Energy Transport and Entropy Production in Quantum Electronics

We solve exactly a generalized Hubbard ring with twisted boundary conditions. The magnitude of the nearest-neighbor hopping depends on the occupations of the sites involved and the term which modifies the number of doubly occupied sites {ital t}{sub {ital AB}}=0. Although {eta}-pairing state with off-diagonal long-range order are part of the degenerate ground state, the behavior of the energy as a function of the twist rules out superconductivity in this limit. A small {ital t}{sub {ital AB}} breaks the degeneracy and for moderate repulsive {ital U} introduce superconducting correlations which lead to {open_quote}{open_quote}anomalous{close_quote}{close_quote} flux quantization. {copyright} {ital 1996 The American Physical Society.}

Microscopic model of a phononic refrigerator

Fil: Arrachea, Liliana del Carmen. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Fisica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisica de Buenos Aires; Argentina