Fermi gases with imaginary mass imbalance and the sign problem in Monte Carlo calculations

Abstract

Fermi gases in strongly coupled regimes, such as the unitary limit, are inherently challenging for many-body methods. Although much progress has been made with purely analytic methods, quantitative results require ab initio numerical approaches, such as Monte Carlo (MC) calculations. However, mass-imbalanced and spin-imbalanced gases are not accessible to MC calculations due to the infamous sign problem. It was recently pointed out that the sign problem, for finite spin imbalance, can be circumvented by resorting to imaginary polarizations and analytic continuation. Large parts of the phase diagram spanned by temperature and polarization then become accessible to MC calculations. We propose to apply a similar strategy to the mass-imbalanced case, which opens up the possibility to study the associated phase diagram with MC calculations. In particular, our analysis suggests that a detection of a (tri-)critical point in this phase diagram is possible. We also discuss calculations in the zero-temperature limit with our approach.

5 pages, 3 figures

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Cited by in corpus (14)

• Complex Langevin and other approaches to the sign problem in quantum many-body physics
• Toward Quantum Computing Phase Diagrams of Gauge Theories with Thermal Pure Quantum States
• Phase structure of mass- and spin-imbalanced unitary Fermi gases
• Phase structure of spin-imbalanced unitary Fermi gases
• Surmounting the sign problem in non-relativistic calculations: a case study with mass-imbalanced fermions
• Inhomogeneous phases in one-dimensional mass- and spin-imbalanced Fermi gases
• Emergence of a pseudogap in the BCS-BEC crossover
• Zero-temperature equation of state of mass-imbalanced resonant Fermi gases
• Integrable families of hard-core particles with unequal masses in a one-dimensional harmonic trap
• Quantum Monte Carlo study of mass-imbalanced Hubbard models
• Polarized fermions in one dimension: density and polarization from complex Langevin calculations, perturbation theory, and the virial expansion
• Thermal equation of state of polarized fermions in one dimension via complex chemical potentials
• Pairing patterns in one-dimensional spin- and mass-imbalanced Fermi gases
• Phases of spin- and mass-imbalanced ultracold Fermi gases in harmonic traps