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TT: Fachverband Tiefe Temperaturen
TT 34: Superconductivity: Theory
TT 34.8: Talk
Wednesday, March 19, 2025, 17:00–17:15, H36
Enhanced entanglement in the pseudogap — •Frederic Bippus1, Juraj Krsnik1, Motoharu Kitatani2,3, Anna Kauch1, Gergö Roosz4, and Karsten Held1 — 1Institute of Solid State Physics, TU Wien, Vienna, Austria — 2Department of Material Science, University of Hyogo, Ako, Hyogo, Japan — 3RIKEN Center for Emergent Matter Sciences (CEMS), Wako, Japan — 4HUN-REN Wigner Research Centre for Physics, Budapest, Hungary
We show significantly enhanced entanglement in the pseudogap regime of the Hubbard model using the dynamical vertex approximation (DGA) [1], a non-local extension to the dynamical mean-field theory. The pseudogap, a partially gapped electronic state, is observed near the superconducting transition in cuprates and nickelates. Leveraging DGA, we compute the quantum variance-a lower bound to the quantum Fisher information [2] from the spin susceptibility directly on the imaginary Matsubara axis. By circumventing the need for ill-controlled analytical continuation, our approach provides a robust framework for probing entanglement depth. The results show good agreement with experimental data [3]. Additionally, Ornstein-Zernike fits provide analytical insights.
This work is supported by the SFB Q-M&S (FWF project ID F86).
[1] Rohringer et al., Rev. Mod. Phys., 90, 025003 (2018);
[2] Frérot et al., Phys. Rev. B, 94, 075121 (2016);
[3] Chan et al., Nat. Commun., 7, 10819 (2016).
Keywords: Pseudogap; Entanglement; Hubbard model; Quantum Fisher information; Quantum Variance