Demonstration of fidelity improvement using dynamical decoupling with
  superconducting qubits
Quantum computers must be able to function in the presence of decoherence.
The simplest strategy for decoherence reduction is dynamical decoupling (DD),
which requires no encoding overhead and works by converting quantum gates into
decoupling pulses. Here, using the IBM and Rigetti platforms, we demonstrate
that the DD method is suitable for implementation in today's relatively noisy
and small-scale cloud based quantum computers. Using DD, we achieve substantial
fidelity gains relative to unprotected, free evolution of individual
superconducting transmon qubits. To a lesser degree, DD is also capable of
protecting entangled two-qubit states. We show that dephasing and spontaneous
emission errors are dominant in these systems, and that different DD sequences
are capable of mitigating both effects. Unlike previous work demonstrating the
use of quantum error correcting codes on the same platforms, we make no use of
post-selection and hence report unconditional fidelity improvements against
natural decoherence.
Bibek Pokharel Namit Anand Benjamin Fortman Daniel Lidar