SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: Method Development

TT 5.6: Vortrag

Montag, 27. März 2023, 10:45–11:00, HSZ 204

Numerical linked cluster expansions for the ordered low-field phase of the transverse-field Ising model — •Matthias Mühlhauser, Max Hörmann, and Kai Phillip Schmidt — Institute for Theoretical Physics I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

We present a hypergraph approach to numerical linked cluster expansions (NLCEs) in the low-field limit of the transverse-field Ising model (TFIM) where the Z2-Symmetry of the TFIM is spontaneously broken and the ground state is magnetically ordered.

Conventional NLCEs in this limit are performed as site expansions where the magnetic order of the ground state is taken into account by longitudinal boundary fields on the graphs.

Here, using an isospectral dual description of the TFIM where the ordered phase is mapped to an effective (symmetry unbroken) polarized phase in the dual desciption, we demonstrate that a straightforward hypergraph expansion can be executed so that no boundary fields are necessary. This allows us to obtain competitive results for the ground-state energy of the ordered low-field phase of the TFIM.