A new paper (postscript), joint with David Poulin, all about operator quantum error correction, a clever way (alas, not my idea!) of protecting quantum states against the effects of noise. The paper provides several sets of easily checkable conditions (both algebraic and information-theoretic) characterizing when operator error-correction is feasible.
Postscript: Dave Bacon has a just put out a nice paper related to operator quantum error-correction, constructing some physically motivated examples of self-correcting quantum memories. This idea – that a quantum system can correct itself – is absolutely fascinating, and runs completely counter to the standard folk “wisdom” about quantum mechanics, namely that quantum states are delicate objects that are easily (and irreversibly) destroyed.