Efficient quantum computation within a disordered Heisenberg spin chain

Chiu Fan Lee, Neil F. Johnson
2004 Physical Review A. Atomic, Molecular, and Optical Physics  
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.
doi:10.1103/physreva.70.052322 fatcat:nqkhdlrmnfcpxcvy37n3ftmrxq