Thermodynamics of Spin-Imbalanced Fermi Gases with SU(N) Symmetric Interaction

TL;DR

This paper extends the thermodynamic analysis of SU(N) Fermi gases to include spin-imbalanced configurations, providing theoretical expressions and experimental validation, revealing significant interaction effects and applications to decoherence.

Contribution

It introduces a theoretical framework for density fluctuations in spin-imbalanced SU(N) Fermi gases and experimentally verifies these predictions in multi-component systems.

Findings

Interaction effects are significant even in highly spin-imbalanced systems.

Theoretical expressions match experimental measurements across temperature ranges.

Application to decoherence processes demonstrates the approach's utility.

Abstract

Thermodynamics of degenerate Fermi gases has been extensively studied through various aspects such as Pauli blocking effects, collective modes, BCS superfluidity, and more. Despite this, multi-component fermions with imbalanced spin configurations remain largely unexplored, particularly beyond the two-component scenario. In this work, we generalize the thermodynamic study of SU($N$) fermions to spin-imbalanced configurations based on density fluctuations. Theoretically, we provide closed-form expressions of density fluctuation across all temperature ranges for general spin population setups. Experimentally, after calibrating the measurements with deeply degenerate $^{173}$Yb Fermi gases under spin-balanced configurations ($N\leq$~6), we examine the density fluctuations in spin-imbalanced systems. Specifically, we investigate two-species and four-species configurations to validate our theoretical predictions. Our analysis indicates that interaction enhancement effects can be significant even in highly spin-imbalanced systems. Finally, as an application, we use this approach to examine the decoherence process. Our study provides a deeper understanding of the thermodynamic features of spin-imbalanced multi-component Fermi gases and opens new avenues for exploring complex quantum many-body systems.