Quantum entanglement, local indicators and effect of external fields in the Kugel-Khomskii model

Abstract

Using the exact diagonalization technique, we determine the energy spectrum and wave functions for finite chains described by the two-spin (Kugel--Khomskii) model with different types of intersubsystem exchange terms. The found solutions provide a possibility to address the problem of quantum entanglement inherent to this class of models. We put the main emphasis on the calculations of the concurrence treated as an adequate numerical measure of the entanglement. We also analyze the behavior of two-site correlation functions considered as a local indicator of entanglement. We construct the phase diagrams of the models involving the regions of nonzero entanglement. The pronounced effect of external fields, conjugated to both spin variables on the regions with entanglement, could both enhance and weaken the entanglement depending on the parameters of the models.

References in corpus (14)

• QuTiP 2: A Python framework for the dynamics of open quantum systems
• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Fingerprints of spin-orbital entanglement in transition metal oxides
• The antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic field
• Multicriticality and entanglement in the one-dimensional quantum compass model
• Von Neumann Entropy Spectra and Entangled Excitations in Spin-Orbital Models
• Exotic spin orders driven by orbital fluctuations in the Kugel-Khomskii model
• Spin-Orbital Entanglement and Phase Diagram of Spin-orbital Chain with $SU(2)\times SU(2)$ Symmetry
• Exact diagonalization solver for the extended dynamical mean-field theory
• Anomalous multi-order Raman scattering in LaMnO_3: a signature of a quantum lattice effect in a Jahn-Teller crystal
• Double quantum-dot engine fueled by entanglement between electron spins
• Mobile orbitons in Ca${}_2$CuO${}_3$: crucial role of the Hund's exchange
• Magnetic phase diagram and quantum phase transitions in a two-species boson model
• The fate of orbitons coupled to phonons