Decoherence by Correlated Noise and Quantum Error Correction

E. Novais, Harold U. Baranger

Published 2005-08-30, updated 2006-07-24Version 2

We study the decoherence of a quantum computer in an environment which is inherently correlated in time and space. We first derive the nonunitary time evolution of the computer and environment in the presence of a stabilizer error correction code, providing a general way to quantify decoherence for a quantum computer. The general theory is then applied to the spin-boson model. Our results demonstrate that effects of long-range correlations can be systematically reduced by small changes in the error correction codes.