Quantum systems are never completely isolated, but instead interact with degrees of freedom in the surrounding environment, eventually leading to decoherence of the system. The conventional route to long-lived quantum coherence involves minimizing coupling to the dissipative bath. Paradoxically, it is possible in principle to instead engineer specific couplings
to a quantum environment that allow dissipation to actually create and preserve coherence. I present a simple scheme to engineer the photon shot noise in a microwave cavity so that it relaxes a qubit towards any desired point on the Bloch sphere. This scheme is inspired by laser cooling in optomechanics and has recently been realized experimentally by the Siddiqi group at Berkeley .
 ‘Cavity-assisted quantum bath engineering,’ K.W. Murch, U. Vool, D. Zhou, S.J. Weber,
S.M. Girvin, I. Siddiqi, Phys. Rev. Lett. (in press) ; arXiv:1207.0053