Quantum Entanglement in Two-Spin Systems in Multiple Pulse NMR Spin Locking with Dephasing Relaxation

Quantum entanglement in two-spin systems in multiple pulse NMR spin locking with dephasing relaxation is studied on the basis of the Lindblad equation. An exact solution for the density matrix of the system for any initial temperature is found. The dependence of the concurrence (which determines quantum entanglement) on the dephasing relaxation rate and the parameters of the multiple pulse sequence is investigated. For different rates of dephasing relaxation, the critical temperature at which entanglement arises is found.