Accessible states in Liouville space. A two-dimensional extension of the universal bound on spin dynamics applied to polarization transfer in INSM Spin-12 systems

Abstract

The universal bound on spin dynamics is extended to two dimensions to describe which and how states in a two-dimensional Liouville subspace can be accessed by unitary transformations. The transfer of I-spin Zeeman order into S-spin Zeeman order for heteronuclear I_NS_M spin-$\text{1}\text{2}$ systems with N + M ⩽ 13 spins is analyzed in detail. These I_NS_M 2D bounds converge to the entropy bounds for spin systems with infinite numbers of I and S spin species but deviate significantly for finite numbers of spins.