Dinamica in timp real in sisteme mesoscopice puternic corelate

WEBSITE: http://mocap.fizicaoradea.ro/projects/pn-ii-id-jrp-2011-1

PEOPLE INVOLVED:

Romanian side:

Prof. Catalin Pascu Moca (Oradea, Romania)

Prof. Gergely Zarand (Budapest, Hungary)

CS II. Valeriu Moldoveanu (INFM, Bucuresti, Romania)

French side:

Prof. Pascal Simon (Orsay, Paris, France)

Dr. Richard Deblock (Orsay, Paris, France)

A. ABSTRACT :

The recent development in fabrication, and operating in a controlled manner of nanoelectronic devices with a few hundred angstroms scale or below, are likely to provide our future technology and serve as basic tools for storing information, quantum computation or spin manipulation. Understanding how these nanometric devices work represents a major challenge for today’s theoretical and experimental physics. To reach this goal we need first to figure out the fundamental issues that govern their behavior and therefore to provide a detailed theory of correlations and transport in atomic scale and mesoscopic structures. More specifically, in order to find efficient ways of manipulating and controlling the spin currents, we must understand the microscopic processes that lead to spin relaxation and dephasing, and eventually their interplay with interactions.

In the present project, our main purpose is to understand non-equilibrium transport through strongly correlated mesoscopic systems. To achieve this goal we shall exploit the expertise of two research partners. The first one, «Laboratoire de Physique des Solides» in Orsay, involves two complementary teams, a theoretical one (led by Pascal Simon) and an experimental one (led by Richard Deblock). The second partner, «University of Oradea» in Romania involves a theoretical team (led by Cătălin Pascu Moca). We plan to study non-equilibrium transport in mesoscopic systems subject to strong interactions, by combining the power of quantum field theoretical methods and numerical analysis with the experimental probation of the theoretical findings. Our research groups will develop new theoretical methods that will enable us to study and understand out of equilibrium, charge and spin transport through these nanometer scale devices. We plan to construct a real time renormalization group scheme, and then use it to investigate frequency dependent quantities that characterize transport under non-equilibrium conditions. Here we have in mind a thorough analysis of charge/spin ac-conductance and noise, scattering rates, relaxation effects and many other transport properties under non-equilibrium conditions. We shall also address the «quantum quench» problem in Kondo correlated systems, i.e. the implications on transport and the modifications in the response functions of a sudden change in the system Hamiltonian. To fulfill this goal, we first plan to carry an ambitious project by developing and extending the currently available numerical renormalization group code, the «Flexible-DMNRG», by incorporating time dependent processes.

On the experimental side we are planning to engineer high frequency quantum detectors for noise measurements in quantum dots in the Kondo regime made of carbon nanotubes. Quantum quench problem shall be investigated experimentally also, by using pulsed voltage probes. It will allow us to monitor different quantities, such as the conductance or noise subject to a quench in one of the system parameters.

We strongly believe that our approach is an optimal one for attacking real-time dynamics problems and that the interplay between the experiment and theory is the strength of the present proposal. More than that, our experimental findings will motivate and guide our theoretical developments along the way.