Concatenating Decoherence-Free Subspaces with Quantum Error Correcting Codes

D. A. Lidar, D. Bacon, K. B. Whaley
1999 Physical Review Letters  
An operator sum representation is derived for a decoherence-free subspace (DFS) and used to (i) show that DFSs are the class of quantum error correcting codes (QECCs) with fixed, unitary recovery operators, and (ii) find explicit representations for the Kraus operators of collective decoherence. We demonstrate how this can be used to construct a concatenated DFS-QECC code which protects against collective decoherence perturbed by independent decoherence. The code yields an error threshold which
more » ... ror threshold which depends only on the perturbing independent decoherence rate.
doi:10.1103/physrevlett.82.4556 fatcat:kkkfugiltna5thuwryiqf667y4