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

Alberto Nocera, University of Tennessee
Event Date and Time: 
Thu, 2018-01-25 14:00 - 15:00
Hennings #318
Local Contact: 
Marcel Franz
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 o ers 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 a ects 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 e ects 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.
[1] A. Nocera, N. D. Patel, E. Dagotto, G. Alvarez, Phys. Rev. B 96, 205120 (2017).
[2] A. Nocera, M. Soltanieh-ha, C. A. Perroni, V. Cataudella, A. E. Feiguin, Phys. Rev. B 90,
195134 (2014).
[3] A. Nocera, F. H. L. Essler, A. E. Feiguin, arXiv:1710.06452 [cond-mat.str-el].
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