  We demonstrate that two remote qubits can be entangled through an optically
active intermediary even if the coupling strengths between mediator and qubits
are different. This is true for a broad class of interactions. We consider two
contrasting scenarios. First, we extend the analysis of a previously studied
gate operation which relies on pulsed, dynamical control of the optical state
and which may be performed quickly. We show that remote spins can be entangled
in this case even when the intermediary coupling strengths are unequal. Second,
we propose an alternative adiabatic control procedure, and find that the system
requirements become even less restrictive in this case. The scheme could be
tested immediately in a range of systems including molecules, quantum dots, or
defects in crystals.
