Time-Dependent Superfluid Local Density Approximation

TL;DR

The paper introduces the time-dependent superfluid local density approximation (TDSLDA), extending density functional theory to study non-linear and strong-field dynamics in superfluid fermionic systems, demonstrated on the unitary Fermi gas.

Contribution

It presents a novel extension of DFT, TDSLDA, enabling the study of non-linear excitations and strong external field responses in superfluid fermionic systems.

Findings

TDSLDA effectively models non-linear superfluid dynamics.

Implementation on the unitary Fermi gas shows high precision results.

Ab initio QMC data helps fix functional coefficients.

Abstract

The time-dependent superfluid local density approximation (TDSLDA) is an extension of the Hohenberg-Kohn density functional theory (DFT) to time-dependent phenomena in superfluid fermionic systems. Unlike linear response theory, which is only valid for weak external fields, the (TDSLDA) approach allows one to study non-linear excitations in fermionic superfluids, including large amplitude collective modes, and the response to strong external probes. Even in the case of weak external fields, the (TDSLDA) approach is technically easier to implement. We will illustrate the implementation of the (TDSLDA) for the unitary Fermi gas, where dimensional arguments and Galilean invariance simplify the form of the functional, and ab initio input from (QMC) simulations fix the coefficients to quite high precision.