Limits to error correction in quantum chaos

We study the correction of errors that have accumulated in an entangled state of spins as a result of unknown local variations in the Zeeman energy (B) and spin-spin interaction energy (J). A nondegenerate code with error rate K can recover the original state with high fidelity within a time t(R) similar or equal to h kappa (1/2)/max(B, J)-independent of the number of encoded qubits. Whether the Hamiltonian is chaotic or not does nor affect this time scale, but it does affect the complexity of the error-correcting code.