We present a near-optimal quantum dynamical decoupling scheme that eliminates general decoherence of a qubit to order $n$ using $O(n^2)$ pulses, an exponential decrease in pulses over all previous decoupling methods. Numerical simulations of a qubit coupled to a spin bath demonstrate the superior performance of the new pulse sequences.

• Received 1 September 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.130501