Seminars

Title:  Correlation effects in electron liquid
 
Abstract: The uniform electron liquid (UEL) paradigm is the basis of most of our current
understanding of the physical properties of electronic systems. The correlated
behaviour of electrons in two- and three-dimensional UEL gives rise to rich emergent
phenomena governed by fundamental quantum mechanics principles. The electron-
electron correlation, which is hard to understand and predict theoretically, causes
quantum phase transitions and renormalisation of bare electron properties.
In this talk, I will discuss the effects of many-body correlations on the phase diagram of
2D- and 3D-UEL obtained by stochastic methods. I will focus on developing real-space
variational and diffusion quantum Monte Carlo (QMC) techniques to calculate the
parameters of Landau Fermi Liquid theory, such as quasi-particle effective mass [1].

References:
[1] S. Azadi, et al., Phys. Rev. Lett. 127, 086401 (2021); Phys. Rev. B 105, 245135 (2022);
Phys. Rev. B 107, L121105 (2023); Phys. Rev. B 108, 115134 (2023); Phys. Rev. B 110,
245145 (2024)

Title: Dynamics of open quantum systems with semi-group influence matrices
 
Abstract: The simulation of dynamics in non-Markovian open quantum systems presents a challenging task if the bath is strongly coupled. A recent approach exploits the structure of temporal correlations in open systems by representing the time-discretized bath influence functional (influence matrix) as a temporal matrix product operator (MPO). I show that, in the case of a stationary bath, time-translation invariance can be exploited to enforce a uniform MPO structure, generating an effective dynamical semigroup for the local dynamics. I demonstrate the numerical utility of this approach through applications to quenches and stationary dynamics in spin-boson and Anderson impurity models. Furthermore, I discuss connections to the modern process tensor formulation of quantum dynamics.