  It is considered the indirect inter-qubit coupling in 1D chain of atoms with
nuclear spins 1/2, which plays role of qubits in the quantum register. This
chain of the atoms is placed by regular way in easy-axis 3D antiferromagnetic
thin plate substrate, which is cleaned from the other nuclear spin containing
isotopes. It is shown that the range of indirect inter-spin coupling may run to
a great number of lattice constants both near critical point of quantum phase
transition in antiferromagnet of spin-flop type (control parameter is external
magnetic field) and/or near homogeneous antiferromagnetic resonance (control
parameter is microwave frequency).
