Complex Langevin and other approaches to the sign problem in quantum many-body physics

CE Berger, L Rammelmüller, AC Loheac, F Ehmann… - Physics Reports, 2021 - Elsevier
We review the theory and applications of complex stochastic quantization to the quantum
many-body problem. Along the way, we present a brief overview of a number of ideas that …

Complex Langevin simulations and the QCD phase diagram: Recent developments

F Attanasio, B Jäger, FPG Ziegler - The European Physical Journal A, 2020 - Springer
In this review we present the current state-of-the-art on complex Langevin simulations and
their implications for the QCD phase diagram. After a short summary of the complex …

Emergence of a Pseudogap in the BCS-BEC Crossover

A Richie-Halford, JE Drut, A Bulgac - Physical Review Letters, 2020 - APS
Strongly correlated Fermi systems with pairing interactions become superfluid below a
critical temperature T c. The extent to which such pairing correlations alter the behavior of …

Finite-temperature equation of state of polarized fermions at unitarity

L Rammelmüller, AC Loheac, JE Drut, J Braun - Physical Review Letters, 2018 - APS
We study in a nonperturbative fashion the thermodynamics of a unitary Fermi gas over a
wide range of temperatures and spin polarizations. To this end, we use the complex …

Pairing patterns in one-dimensional spin-and mass-imbalanced Fermi gases

L Rammelmüller, JE Drut, J Braun - SciPost Physics, 2020 - scipost.org
We study spin-and mass-imbalanced mixtures of spin-$\tfrac {1}{2} $ fermions interacting via
an attractive contact potential in one spatial dimension. Specifically, we address the …

Virial coefficients of one-dimensional and two-dimensional Fermi gases by stochastic methods and a semiclassical lattice approximation

CR Shill, JE Drut - Physical Review A, 2018 - APS
We map out the interaction effects on the first six virial coefficients of one-dimensional Fermi
gases with zero-range attractive and repulsive interactions and the first four virial coefficients …

Thermodynamics of spin-orbit-coupled bosons in two dimensions from the complex Langevin method

F Attanasio, JE Drut - Physical Review A, 2020 - APS
We investigate the thermal properties of interacting spin-orbit-coupled bosons with contact
interactions in two spatial dimensions. To that end, we implement the complex Langevin …

Density profiles and correlations of harmonically trapped ultracold fermions via complex Langevin

F Attanasio, M Bauer, JM Pawlowski - arxiv preprint arxiv:2212.11314, 2022 - arxiv.org
Standard lattice formulations of non-relativistic Fermi gases with two spin components suffer
from a sign problem in the cases of repulsive contact interactions and attractive contact …

Complex Langevin study for polarons in a one-dimensional two-component Fermi gas with attractive contact interactions

TM Doi, H Tajima, S Tsutsui - Physical Review Research, 2021 - APS
We investigate a polaronic excitation in a one-dimensional spin-1/2 Fermi gas with contact
attractive interactions, using the complex Langevin method, which is a promising approach …

Virial expansion of attractively interacting Fermi gases in one, two, and three dimensions, up to fifth order

Y Hou, JE Drut - Physical Review A, 2020 - APS
The virial expansion characterizes the high-temperature approach to the quantum-classical
crossover in any quantum many-body system. Here, we calculate the virial coefficients up to …