Asban, Ofek
Postdoc
 asban@post.bgu.ac.il
 Research type
 Theoretical
 Research topics
We investigate the effects of interactions and disorder in open quantum systems.
Past Projects:
(1) Using a meanfield master equation approach we calculate the effects of disorder and interactions on the relaxation of interacting Twolevel systems (dipolar spinglass) near equilibrium. We found that interactions increase the relaxation rate contrary to the Electronglass system.(2) We derived an effective action that describes the effects of disordered Fermi liquid on the conductance of the Electronglass system coupled to phonons. We found competing effects between the renormalization of the density of states which tends to increase the conductivity and the polaronic effect which decreases it. The total effect in a wide regime of parameters was a reduction in the conductivity as observed in experiments.
(3) We investigate the effects of corrections beyond the static (Hartree) meanfield solution on the conductance of the electron glass system. Using the $\Psi$ functional approach (a generalization of the Luttinger–Ward functional) we calculate systematically the selfenergy corrections to the propagators of the model. The different contributions are (1) renormalization of the density of states, (2) renormalization of the phonon polaronic effect, (3) renormalization electronhole interactions (ladder resummation) (4) The electronic polaronic effect.
Contributions #1  #3 seem to contribute to the increase of the transition rate while contribution #4 might decrease or increase decreases it.
It is then left to estimate qualitatively if the overall effect increases or decreases the conductivity.Thesis link:
http://dx.doi.org/10.13140/RG.2.2.26895.92320Secondary project:
LocalizationDelocalization and DampedOverdamped transitions of the Spinboson model at finite temperature. Researcher identification
 Google Scholar
Education

2016
2021,
PhD
Dynamics of Disordered and Interacting Open Quantum Systems
with Moshe Schechter 
2014
2016,
MSc
Dynamics and phase transition of dissipative systems
with Moshe Schechter
Publications
 Asban, O. and Burin, A. and Shnirman, A. and Schechter, M., "Polaronic Effect Of A Metal Layer On Variable Range Hopping", Phys. Rev. B 103, 045129 (2021)
 Asban, Ofek And Amir, Ariel And Imry, Yoseph And Schechter, Moshe, "Effect Of Interactions And Disorder On The Relaxation Of TwoLevel Systems In Amorphous Solids", Physical Review B 95, 144207 (2017)