  Arrays of covalently bound organic molecules possess potential for
light-harvesting and energy transfer applications due to the strong coherent
dipole-dipole coupling between the transition dipole moments of the molecules
involved. Here, we show that such molecular systems, based on
perylene-molecules, can be considered as arrays of qubits that are amenable for
laser-driven quantum coherent control. The perylene monomers exhibit dephasing
times longer than four orders of magnitude a typical gating time, thus allowing
for the execution of a large number of gate operations on the sub-picosecond
timescale. Specifically, we demonstrate quantum logic gates and entanglement in
bipartite (dimer) and tripartite (trimer) systems of perylene-based arrays. In
dimers, naturally entangled states with a tailored degree of entanglement can
be produced. The nonlocality of the molecular trimer entanglement is
demonstrated by testing Mermin's (Bell-like) inequality violation.
