Dvira Segal
Department of Chemistry
University of Toronto


My research deals with theoretical and computational aspects of the dynamics of out-of-equilibrium, many-body, quantum dissipative systems with implications both in basic science, and for device applications. Some of the ongoing projects are:

(1) Heat transfer in molecular junctions: In recent years there has been a growing interest in nanomechanics of quantum systems: construction and study of nano-level and molecular scale mechanical systems manifesting quantum effects. Our goal is to understand the classical and quantal aspects of heat transfer through low dimensional systems. Some of the questions we ask are: What are the mechanisms of heat transfer in the nanoscale? How does the thermal conductance depend on the internal structure, temperature, length? What is the effect of dimensionality? What is the role of Coherences in the dynamics?

Our work is done at three different levels: (i) We develop first principle formulations of phononic heat transfer at low dimensional systems. (ii) We construct simple "toy" models, that capture the basic factors affecting energy transport in molecular junctions. (iii) We use molecular dynamic simulations to describe vibrational energy transfer between interfaces.

(2) Spin dynamics in non-equilibrium systems: Out-of-equilibrium magnetic effects in the nanoscale are interesting both from the fundamental point of view, and practically, for designing efficient nanoscale spin-electronic devices. We use perturbative calculations, as well as exact numerical techniques (path integral, Numerical renormalization group) and study the Kondo effect in molecular systems, under an external bias voltage, which drives the system out-of-equilibrium. We observe reach dynamics with a complicated phase diagram, showing regimes of relaxation and localization, similarly to the spin-boson model. This project helps us pinpoint on the fundamentally unique dissipation processes taking place in nonequilibrium many-body systems, in comparison to their equilibrium counterparts.