1210.1338 (Zhen-Yu Wang et al.)

No-go theorem and optimization of dynamical decoupling against noise
with soft cutoff    [PDF]

Zhen-Yu Wang, Ren-Bao Liu

We study the performance of dynamical decoupling in suppressing decoherence caused by soft-cutoff Gaussian noise, using short-time expansion of the noise correlations and numerical optimization. For the noise correlations with odd power terms in the short-time expansion, there exists no dynamical decoupling scheme to eliminate the decoherence to arbitrary orders of the short time, regardless of the timing or pulse shaping of the control under the population conserving condition. We formulate the equations for optimizing pulse sequences for dynamical decoupling that minimizes decoherence up to the highest possible order of the short-time expansion. In particular, we show that the Carr-Purcell-Meiboom-Gill sequence is optimal in short-time limit for the noise correlations with a linear order term in the time expansion.

View original: http://arxiv.org/abs/1210.1338