Insights into quantum many-body systems through Hamiltonian reconstruction.

Title: Insights into quantum many-body systems through Hamiltonian reconstruction.
Speaker: Prof. Annabelle Bohrdt (Institute of Theoretical Physics, University of Regensburg)
Start Date/Time: 2023-05-10 / 15:30 (Taipei time)
End Date/Time: 2023-05-10 / 16:30
Host: Prof. Chia-Min Chung (NSYSU)

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Unveiling the microscopic origins of quantum many-body phases dominated by the interplay of spin and charge degrees of freedom constitutes one of the central challenge in modern strongly correlated many-body physics. When holes hop through a background of insulating spins, they displace their positions, which in turn induces effective frustration in the magnetic background. However, the precise quantification of this effect in a quantum many-body system is an extremely challenging task. 

We use Hamiltonian learning schemes to associate the hole-removed spin background with a purely magnetic Hamiltonian. This approach allows us to quantify the effect of the hole-motion on the spin background, using Fock space snapshots at intermediate temperatures, readily accessible to quantum gas microscopes.

In particular, we study a one-dimensional Fermi-Hubbard system, and reveal effects of charge correlations on the spin correlations through Hamiltonian reconstruction. We next consider a model in mixed-dimensions, where holes are restricted to move in one dimension, but spin couplings are two-dimensional, and establish a quantitative understanding of the interplay of spin and charge through the introduction of frustrating diagonal bonds.