Recovery in quantum error correction for general noise without   measurement
  It is known that one can do quantum error correction without syndrome measurement, which is often done in operator quantum error correction (OQEC). However, the physical realization could be challenging, especially when the recovery process involves high-rank projection operators and a superoperator. We use operator theory to improve OQEC so that the implementation can always be done by unitary gates followed by a partial trace operation. Examples are given to show that our error correction scheme outperforms the existing ones in various scenarios. 
Chi-Kwong Li, Mikio Nakahara, Yiu-Tung Poon, Nung-Sing Sze, Hiroyuki   Tomita
quant-ph math.FA