Dynamic correlations in quantum magnets

Vimalesh Kumar Vimal, V. Subrahmanyam

We investigate the dynamics of a spin chain with Kitaev-type interaction in a transverse magnetic field, for both a constant field and a periodically kicked field. We investigate analytically the revivals in the dynamical behavior of the magnetization, and measures of local quantum correlations, the concurrence measure of the entanglement, and the quantum discord. The magnetization revivals are seen even for larger chain lengths, with reduced revival peaks, both near and away from the critical point at zero magnetic field. The quantum entanglement and correlation measures, contrary to the expected behavior, exhibit reduced quantum correlations in the critical region, compared to the region away from the critical point. The concurrence is larger than the quantum discord away from the critical region. The pair entanglement is near zero for all times in the critical region, though the quantum discord is nonzero, capturing the underlying diagonal correlations. The kicked magnetic field dynamics shows similar evolution for the magnetization and quantum correlations. For special values of the kicking period, the concurrence shows alternates between zero and nonzero values for successive kicks in the noncritical region.

Gabe Schumm

Tim D. Reid

Masaya Nakagawa, Naoto Tsuji, Norio Kawakami +1 more

In quantum magnetism, the virtual exchange of particles mediates an interaction between spins. Here, we show that an inelastic Hubbard interaction fundamentally alters the magnetism of the Hubbard model due to dissipation in spin-exchange processes, leading to sign reversal of magnetic correlations in dissipative quantum dynamics. This mechanism is applicable to both fermionic and bosonic Mott insulators, and can naturally be realized with ultracold atoms undergoing two-body inelastic collisions. The dynamical reversal of magnetic correlations can be detected by using a double-well optical lattice or quantum-gas microscopy, the latter of which facilitates the detection of the magnetic correlations in one-dimensional systems because of spin-charge separation. Our results open a new avenue toward controlling quantum magnetism by dissipation.

D. Bitko

Su-Bok Ri, Gwang-Jin Kim, Ha Kim +1 more

In this paper we argue about the quantum correlation (quantum entanglement and geometric quantum discord) in four-qubit XXZ Heisenberg Model. Here, the influence of uniform magnetic field on the dynamics of quantum correlation in cases of the antiferromagnetism has been mainly investigated. According to the results, it has been illustrated that the role of the uniform magnetic field on the dynamics of quantum correlation depends on the selection of the initial state. Furthermore, geometric quantum discord exhibits greater robustness compared to quantum entanglement. Also results show that the max values of quantum correlations decrease and the duration of quantum entanglement sudden death gets longer as purity parameter decreases, and that exchange interaction can substantially make an effect on the dynamics of the quantum correlation.