QUANTUM DYNAMICS OF DOUBLE QUBIT IN A SPIN STAR LATTICE WITH AN x-y INTERACTION

摘要

The dynamics of two spins-1/2 interacting with a spin-bath via the quantum Heisenberg x-y coupling is studied. The purity, z-component summation and the concurrence of the central subsystem are determined by the Laguerre polynomial scheme. It is found that (i) at a low temperature, the uncoupled subsystem in a product state can be entangled by the bath, which is tested by the Peres-Horodecki separability; (ii) the resistance of the subsystem in Bell states to the destroy effect from the bath increases with its inner-coupling strength.