Determination of ground state properties in quantum spin systems by single qubit unitary operations and entanglement excitation energies

Abstract

We introduce a method for analyzing ground state properties of quantum many body systems, based on the characterization of separability and entanglement by single subsystem unitary operations. We apply the method to the study of the ground state structure of several interacting spin-1/2 models, described by Hamiltonians with different degrees of symmetry. We show that the approach based on single qubit unitary operations allows to introduce {\it ``entanglement excitation energies''}, a set of observables that can characterize ground state properties, including the quantification of single-site entanglement and the determination of quantum critical points. The formalism allows to identify the existence and location of factorization points, and a purely quantum {\it ``transition of entanglement''} that occurs at the approach of factorization. This kind of quantum transition is characterized by a diverging ratio of excitation energies associated to single-qubit unitary operations.

To appear in Phys. Rev. A

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Cited by in corpus (14)

• Theory of ground state factorization in quantum cooperative systems
• Separability and ground state factorization in quantum spin systems
• Probing Quantum Frustrated Systems via Factorization of the Ground State
• Factorization and entanglement in general XYZ spin arrays in non-uniform transverse fields
• Entanglement quantification by local unitaries
• Separability and entanglement in finite dimer-type chains in general transverse fields
• Factorization and criticality in finite XXZ systems of arbitrary spin
• When finite-size corrections vanish: The S=1/2 XXZ model and the Razumov-Stroganov state
• Optimal correlations in many-body quantum systems
• Non-transverse factorizing fields and entanglement in finite spin systems
• Factorization in XYZ spin systems under general fields and separable ground state engineering
• Entanglement in finite spin rings with noncollinear Ising interaction
• Separability and parity transitions in $XYZ$ spin systems under nonuniform fields
• Multipartite entanglement and few-body Hamiltonians