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Entanglement and factorized ground states in two-dimensional quantum antiferromagnets
Tommaso Roscilde1, Paola Verrucchi, Andrea Fubini
1Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA.
Physical Review Letters
|May 21, 2005
Summary
In anisotropic quantum magnets, a specific magnetic field eliminates entanglement, revealing a classical-like state. This transition is marked by a dip in entanglement ratios, indicating a quantum phase transition.
Area of Science:
- Condensed matter physics
- Quantum magnetism
- Quantum information theory
Background:
- Anisotropic two-dimensional S=1/2 antiferromagnets are complex quantum systems.
- Understanding entanglement in these systems under external fields is crucial.
Purpose of the Study:
- To investigate the ground state properties of anisotropic S=1/2 antiferromagnets in a uniform magnetic field.
- To identify conditions under which quantum entanglement vanishes.
- To characterize field-induced quantum phase transitions.
Main Methods:
- Utilizing exact results and quantum Monte Carlo simulations.
- Analyzing entanglement of formation.
- Calculating energy and state forms.
- Examining the pairwise-to-global entanglement ratio (R).
Main Results:
- The ground state adopts a classical-like product state at a specific magnetic field value and orientation, where entanglement disappears.
- Analytical expressions for the energy and state form were derived.
- A novel class of exactly solvable two-dimensional quantum models was identified.
- A cusp minimum in the entanglement ratio R was found to characterize the quantum phase transition.
Conclusions:
- A unique field configuration can lead to the loss of quantum correlations in these magnetic systems.
- The study introduces exactly solvable models with potential applications in quantum information.
- The entanglement ratio R serves as a robust indicator of quantum criticality and multipartite entanglement enhancement.