Abstract
Phys. Rev. A 70, 052322 (2004) We show that efficient quantum computation is possible using a disordered
Heisenberg spin-chain with `always-on' couplings. Such disorder occurs
naturally in nanofabricated systems. Considering a simple chain setup, we show
that an arbitrary two-qubit gate can be implemented using just three
relaxations of a controlled qubit, which amounts to switching the on-site
energy terms at most twenty-one times.
