We experimentally demonstrate coherence recovery of singlet-triplet superpositions by interlacing qubit rotations between Carr-Purcell (CP) echo sequences. We then compare performance of Hahn, CP, concatenated dynamical decoupling (CDD) and Uhrig dynamical decoupling (UDD) for singlet recovery. In the present case, where gate noise and drift combined with spatially varying hyperfine coupling contribute significantly to dephasing, and pulses have limited bandwidth, CP and CDD yield comparable results, with T2 ~ 80 microseconds.
@article{arxiv.1007.4255,
title = {Interlaced Dynamical Decoupling and Coherent Operation of a Singlet-Triplet Qubit},
author = {C. Barthel and J. Medford and C. M. Marcus and M. P. Hanson and A. C. Gossard},
journal= {arXiv preprint arXiv:1007.4255},
year = {2015}
}