Quantum chaos and fluctuations in isolated nuclear spin systems

TL;DR

This paper uses numerical simulations to explore quantum chaos, state structure, magnetic susceptibility, and noise spectra in isolated nuclear spin systems, relevant for ultra-cold condensed matter experiments searching for fundamental symmetry violations.

Contribution

It provides new insights into the spectral properties and quantum chaos in isolated nuclear spins, with implications for precision measurements at ultra-low temperatures.

Findings

Magnetic noise spectrum is identical for positive and negative temperatures

Quantum states exhibit structure consistent with quantum chaos

Curie law validity investigated at microkelvin temperatures

Abstract

Using numerical simulations we investigate dynamical quantum chaos in isolated nuclear spin systems. We determine the structure of quantum states, investigate the validity of the Curie law for magnetic susceptibility and find the spectrum of magnetic noise. The spectrum is the same for positive and negative temperatures. The study is motivated by recent interest in condensed-matter experiments for searches of fundamental parity- and time-reversal-invariance violations. In these experiments nuclear spins are cooled down to microkelvin temperatures and are completely decoupled from their surroundings. A limitation on statistical sensitivity of the experiments arises from the magnetic noise.