Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 4: Many-Body Quantum Dynamics 1 (joint session DY/TT)

TT 4.1: Talk

Monday, September 5, 2022, 10:00–10:15, H20

Squeezed-field path integral method for fermionic superfluid systems — •Dapeng Li — Luruper Chaussee 149, Gebäude 69 22761 Hamburg

We develop a squeezed field path integral method for fermionic su- perfluid systems including BCS superconductors and unconventional superfluid systems. In this method, the squeezing parameters of the Bogoliubov transformation for fermions become dynamical variables representing bosonic collective excitations on superfluid systems. Us- ing this method, we analyze the spectral function of the single parti- cle excitations for BCS superconductors. We demonstrate that, as a main consequence of the method, a bosonic branch corresponding to the Higgs mode appears as a sideband branch, in addition to the single particle excitation branches obtained from the BCS mean-field approx- imation. Moreover, we show that our framework can also be applied to low-energy excitations of systems with unconventional orders.