A decoupling-free solid-state NMR quantum computer

We present a decoupling-free solid-state NMR quantum computer with a switchable controlled-NOT gate installed in a one-dimensional antiferromagnet with a spin gap. The gate switching is realized by a local singlet-triplet excitation across the spin gap, which induces a Suhl-Nakamura-type internuclear coupling between control and target qubits. Naive calculation for the coupling strength with some realistic parameters indicates that the coupling can be strong enough to serve as a controlled-NOT gate