Low-dimensional fluctuations and pseudogap in Gaudin-Yang Fermi gases

Hiroyuki Tajima,Shoichiro Tsutsui,Takahiro M Doi

doi:10.1103/physrevresearch.2.033441

Hiroyuki Tajima, Shoichiro Tsutsui + Show 1 more

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https://doi.org/10.1103/physrevresearch.2.033441

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Abstract

Pseudogap is a ubiquitous phenomenon in strongly correlated systems such as high-$T_{\rm c}$ superconductors, ultracold atoms and nuclear physics. While pairing fluctuations inducing the pseudogap are known to be enhanced in low-dimensional systems, such effects have not been explored well in one of the most fundamental 1D models, that is, Gaudin-Yang model. In this work, we show that the pseudogap effect can be visible in the single-particle excitation in this system using a diagrammatic approach. Fermionic single-particle spectra exhibit a unique crossover from the double-particle dispersion to pseudogap state with increasing the attractive interaction and the number density at finite temperature. Surprisingly, our results of thermodynamic quantities in unpolarized and polarized gases show an excellent agreement with the recent quantum Monte Carlo and complex Langevin results, even in the region where the pseudogap appears.

Highlights

INTRODUCTIONA pseudogap phenomenon, which is the suppression of the density of states (DOS) around a Fermi level, has been a central issue in strongly correlated quantum many-body systems such as high-Tc superconductors [1,2,3,4,5], ultracold atoms [6,7,8,9,10,11,12,13,14], and nuclear and quark matter [15,16,17,18,19,20]
We show that the single-particle excitation spectra exhibit the pseudogapped structure due to pairing fluctuations in the region where the validity is guaranteed by the comparison with quantum Monte Carlo (QMC) results for the thermodynamic quantity
We have investigated low-dimensional fluctuation effects in an attractive Gaudin-Yang Fermi gas at finite temperature within the diagrammatic approach

Summary

INTRODUCTION

A pseudogap phenomenon, which is the suppression of the density of states (DOS) around a Fermi level, has been a central issue in strongly correlated quantum many-body systems such as high-Tc superconductors [1,2,3,4,5], ultracold atoms [6,7,8,9,10,11,12,13,14], and nuclear and quark matter [15,16,17,18,19,20]. Low-energy effective field-theory descriptions, such as Tomonaga-Luttinger liquid [62] have been employed frequently in 1D Such approaches give exact results at zero temperature, it is not the case at finite temperature where the Fermi step is softened. Precise results of this 1D fermionic system at finite temperature were obtained by TBA [63,64,65] and a recent state-of-the-art work of quantum Monte Carlo (QMC) simulation performed by Hoffman et al [66]. We elucidate pairing fluctuation effects in 1D Gaudin-Yang Fermi gas at finite temperature within the diagrammatic approach, which has successfully been applied to higher-dimensional systems [6,9,11,12,14].

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