Finite-temperature spin and charge transport in integrable one-dimensional Mott-Hubbard insulators

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Statistical Mechanics

Background:

• The one-dimensional (1D) Hubbard model is a key system for understanding Mott-Hubbard insulators.
• Previous studies suggested anomalous superdiffusive spin and charge transport at T>0 for the 1D Hubbard model at h=μ=0.
• These predictions relied on hydrodynamic theory and Kardar-Parisi-Zhang (KPZ) scaling.

Purpose of the Study:

• To review recent findings that correct the understanding of charge transport in the 1D Hubbard model.
• To address the discrepancy between hydrodynamic theory/KPZ scaling predictions and actual behavior.
• To identify the source of the failure in previous theoretical models.

Main Methods:

• Review of recent theoretical results.
• Analysis of symmetry properties at the h=μ=0 point.
• Comparison of hydrodynamic theory and KPZ scaling with corrected models.

Main Results:

• Finite-temperature charge transport in the 1D Hubbard model at h=μ=0 is normal diffusive, not anomalous superdiffusive.
• The previous theoretical failure stemmed from incorrectly assuming an SO(4) symmetry.
• The correct analysis must include the quantum effects of the τ-translational U(1) symmetry beyond SO(4).

Conclusions:

• Hydrodynamic theory and KPZ scaling predictions for charge transport are inaccurate for the 1D Hubbard model at the h=μ=0 point.
• The correct description of transport requires acknowledging the full [SO(4)×U(1)]/Z2 symmetry.
• This work highlights the importance of subtle symmetry considerations in strongly correlated electron systems.