Chaos-controlled switching between entanglement and coherence

TL;DR

This paper demonstrates how chaos can be used to switch between entanglement and coherence in quantum systems, enabling control over these resources through eigenstate manipulation in different chaos regimes.

Contribution

It introduces chaos-controlled switching between entanglement and coherence, using eigenstate properties and avoided crossings in both wave-chaotic billiards and many-body quantum systems.

Findings

Eigenfunction entanglement and basis coherence distinguish chaos regimes.

Chaos enables switchable entanglement and coherence modes.

Global field tilt toggles between modes in the Ising chain.

Abstract

Controlling entanglement and coherence is central to quantum information, yet the two resources often exhibit antagonistic trends and are difficult to optimize within a single platform. Here we show that chaos enables switchable eigenstate resources: avoided crossings in soft- versus strong- chaos windows selectively realize an entanglement-peak mode or a coherence-peak mode within the same system. Crucially, this chaos-controlled inversion is not tied to a particular notion of subsystems, appearing both in single-wave settings and in genuine many-body settings. From the quantum-chaos perspective, conventional diagnostics based on avoided-crossing phenomenology and eigenmode delocalization are insufficient; eigenfunction entanglement and basis coherence provide the missing discriminants. Using two wave-chaotic billiards and a tilted-field Ising chain, we track the information-theoretic response of eigenstates across localized hybridization windows. Even when avoided-crossing phenomenology and delocalization are comparable, the entanglement and coherence responses invert between soft- and strong-chaos regimes. In the Ising chain, a single microscopic knob, the global field tilt, toggles between the two operating modes and reveals a trade-off in which off-diagonal correlations grow as diagonal populations dip. Our diagnostics require only reduced states (or their spectra) and are compatible with mode imaging in wave-chaos resonators and randomized measurements in programmable spin simulators.