Quantum Liang Information Flow Probe of Causality across Critical Points

Area of Science:

• Quantum physics
• Quantum many-body systems
• Quantum information theory

Background:

• Causation in quantum many-body systems is understudied, despite its importance.
• Distinguishing causation from correlation is crucial for understanding quantum phenomena.

Purpose of the Study:

• To quantify causality in quantum many-body systems using quantum Liang information flow.
• To investigate quantum causation across phase diagrams, focusing on quantum criticality.

Main Methods:

• Application of quantum Liang information flow, a novel causation measure.
• Analysis of quantum many-body systems across spectrum-wide critical points and second-order phase transitions.
• Examination of both integrable and nonintegrable systems.

Main Results:

• Quantum causation exhibits distinct hallmarks at criticality, differing from correlation measures.
• Causation qualitatively aligns with quasiparticle information propagation in integrable systems.
• Enhanced quantum nonlocality and unique features are observed near criticality.

Conclusions:

• Quantum Liang information flow effectively quantifies causality in complex quantum systems.
• Quantum causation reveals unique behaviors at critical points, distinct from correlations.
• The study advances the understanding of information propagation and nonlocality in quantum matter.