Long-Range Entanglement near a Kondo-Destruction Quantum Critical Point

Area of Science:

• Condensed Matter Physics
• Quantum Information Theory

Background:

• The Kondo impurity model describes a magnetic impurity interacting with conduction electrons.
• Quantum critical points (QCPs) are fascinating states of matter where quantum fluctuations drive phase transitions.
• Understanding quantum entanglement is crucial for developing quantum technologies.

Purpose of the Study:

• To investigate quantum entanglement in a Kondo impurity model with a vanishing density of states at the Fermi energy.
• To characterize the behavior of entanglement entropy near a Kondo-destruction quantum critical point.
• To explore the implications for heavy-fermion quantum criticality and entanglement calculations.

Main Methods:

• Numerical renormalization group (NRG) calculations.
• Analysis of impurity contribution to entanglement entropy (S_{e}^{imp}).
• Study of a Kondo impurity model with a specific vanishing density of states (ρ(ϵ)∝|ϵ|^{r}).

Main Results:

• A characteristic entanglement length scale (R*) was identified, distinguishing regions of strong and weak entanglement.
• Entanglement entropy exhibits universal behavior as a function of R/R* within different phases.
• The entanglement length R* diverges at the quantum critical point, indicating a growing Kondo screening cloud.

Conclusions:

• The study reveals a novel quantum critical phenomenon driven by entanglement in the Kondo model.
• The findings have implications for understanding heavy-fermion systems and quantum criticality.
• The numerical renormalization group provides a powerful tool for studying entanglement in complex quantum systems.