Influence of Dzyaloshinskii–Moriya interaction in the sinusoid magnetic field on the thermal quantum correlation of inhomogeneous Heisenberg spin chain

We investigate the anisotropic Heisenberg XXZ spin chain that possesses Dzyaloshinskii–Moriya (DM) interaction and discuss the behavior characteristics of the thermal quantum correlation (thermal quantum discord and thermal quantum entanglement) in the inhomogeneous magnetic field that is manipulated by sinusoidal wave. The results indicate that the DM interaction strengthens the thermal correlation such that the stronger the DM interaction is, the more obvious it strengthens. We can control the thermal correlation through externally adding an inhomogeneous magnetic field that a relative stable range can be formed where the thermal quantum correlation is almost foreign to the coupling coefficient of z-direction spin, thereby the thermal quantum correlation is controlled and enhanced.     

Universal quantum gates between distant quantum dot spins

We propose a scheme to engineer a nonlocal two-qubit phase gate between two remote quantum-dot spins in cavities. As the effect of cavity decay is considered and strong coupling condition is not used, the scheme has good adaptability. Along with single qubit operations, one can perform in principle various types of distributed quantum information processing.