Relevant, though not yet practical: quantum error correction [1]. There's a threshold we have to get over, then it gets a lot easier. edit and a reddit comment

Relevant, though not yet practical: quantum error correction [1]. There's a threshold we have to get over, then it gets a lot easier. edit and a reddit commenter mentioned this link saying that the current record for storing a qubit is 39 minutes [2]. Which is about three orders of magnitude larger than I would have expected, if you discount "just shoot the photon into space!" solutions. 1: http://en.wikipedia.org/wiki/Quantum_error_correction http://en.wikipedia.org/wiki/Quantum_error_correction 2: http://www.livescience.com/41217-long-quantum-bit-achieved.html http://www.livescience.com/41217-long-quantum-bit-achieved.h...