Quantum simulations of dynamical response functions for strongly correlated quasi-one dimensional materials

Research Associate candidate presentation

Speaker: Alberto Nocera, Department of Physics and Astronomy, The University of Tennessee,
Date & Time: Thursday, 2018-01-25 14:00 - 15:00
Location: Hennings 318
Local Contact: Marcel Franz
Intended Audience:

Dynamical response functions of strongly correlated quantum systems provide crucial infor-
mation about their complex physical behavior. For example, in layered high Tc superconduc-
tors, pairing could be linked to the unusual structure of spin excitations with a spin gap at low
energies and a magnetic resonance with an universal hourglass dispersion. Angle resolved pho-
toemission spectroscopy represents another invaluable tool, providing direct access to the pairing
symmetry, quasi-particle dispersions, and band structure topology. However, the computation of
response functions starting from model Hamiltonians for correlated systems in layered geometries
is a formidable task because of the absence of accurate many-body tools, particularly when many
orbitals are active. Fortunately, in certain cases layered materials are made of weakly coupled
quasi-one dimensional building blocks, such as chains or ladders. This oers to theorists the
unique opportunity to study both the ground-state and excitation spectra of these quasi-one di-
mensional systems with numerically exact techniques, such as the density matrix renormalization
group method (DMRG). In the rst part of the presentation, I will show DMRG results for the
dynamical spin structure factor of the Hubbard model in a two-leg ladder geometry [1], provid-
ing a criterion to link the pairing strength directly to the magnetic excitation spectrum. In the
second part, I will show how the lattice aects the properties of the photoemission spectrum of
a hole doped one-dimensional Hubbard chain [2]. Because of its importance for real applications,
I will also address the eects of a nite temperature on the photoemission spectrum in the Mott
insulating regime, showing a redistribution of spectral weight inside the Mott gap [3]. Finally, I
will discuss the implications of our results for experiments and outline future directions of research.