Entanglement dynamics of spin systems in pure states

Abstract

We investigate numerically the appearance and evolution of entanglement in spin systems prepared initially in a pure state. We consider the dipolar coupling spin systems of different molecular structures: benzene ${\text{C}}_{6}{\text{H}}_{6}$, cyclopentane ${\text{C}}_{5}{\text{H}}_{10}$, sodium butyrate ${\text{CH}}_{3}{({\text{CH}}_{2})}_{2}{\text{CO}}_{2}\text{Na}$, and calcium hydroxyapatite ${\text{Ca}}_{5}(\text{OH}){({\text{PO}}_{4})}_{3}$. Numerical simulations show that the close relationship exists between the intensity of second order (2Q) coherences and concurrences of nearest spins in a cyclopentane molecule.