Quantum error correction for continuously detected errors
by
Charlene Ahn
Caltech
Coauthors: H. M. Wiseman, G. J. Milburn, Kurt Jacobs

We show that quantum feedback control can be used as a quantum error correction process for errors induced by weak continuous measurement. In particular, when the error model is restricted to one, perfectly measured, error channel per physical qubit, quantum feedback can act to perfectly protect a stabilizer codespace. Using the stabilizer formalism we derive an explicit scheme, involving feedback and an additional constant Hamiltonian, to protect an (n-1)-qubit logical state encoded in n physical qubits. This works for both Poisson (jump) and white-noise (diffusion) measurement processes. In addition, universal quantum computation is possible in this scheme. As an example, we show that detected-spontaneous emission error correction with a driving Hamiltonian can greatly reduce the amount of redundancy required to protect a state from that which has been previously postulated. The multiple-channel case is also considered, and it is shown that for arbitrary numbers of channels n physical qubits can protect n-2 logical qubits.

Paper reference: arXiv:quant-ph/0302006

Date received: March 31, 2004