Observation of non-Fermi liquid physics in a quantum critical metal via quantum loop topography

TL;DR

This paper demonstrates that combining sign problem-free quantum Monte Carlo with quantum loop topography enables the detection of non-Fermi liquid behavior near quantum critical points in strongly correlated metals, using minimal training data.

Contribution

It introduces a novel machine learning approach that can identify non-Fermi liquid regimes in microscopic models with limited training, advancing understanding of quantum criticality.

Findings

Successfully identifies non-Fermi liquid regimes near quantum critical points.

Uses minimal training data to detect complex quantum phases.

Provides proof-of-principle for physics-inspired machine learning in condensed matter.

Abstract

Non-Fermi liquid physics is a ubiquitous feature in strongly correlated metals, manifesting itself in anomalous transport properties, such as a $T$-linear resistivity in experiments. However, its theoretical understanding in terms of microscopic models is lacking despite decades of conceptual work and attempted numerical simulations. Here we demonstrate that a combination of sign problem-free quantum Monte Carlo sampling and quantum loop topography, a physics-inspired machine learning approach, can map out the emergence of non-Fermi liquid physics in the vicinity of a quantum critical point with little prior knowledge. Using only three parameter points for training the underlying neural network, we are able to reproducibly identify a stable non-Fermi liquid regime tracing the fan of a metallic quantum critical points at the onset of both spin-density wave and nematic order. Our study thereby provides an important proof-of-principle example that new physics can be detected via unbiased machine-learning approaches.