Error correction for a spin quantum computer

The problems of error correction in a spin quantum computer are discussed. For digital processing in the Ising and Heisenberg chains driven by a resonant electromagnetic field, the simple schemes are suggested which provide correction of errors caused by imperfect pi pulses, and prevent the most significant errors caused by the nonresonant action of rr pulses. The probability of error caused by the Heisenberg interaction during the action of rr pulses is estimated. For quantum computations in spin systems a principal opportunity to correct the phase errors, based on Steane's three quantum-bits scheme, is described.