  Dynamical decoupling is a technique that protects qubits against noise. The
ability to preserve quantum coherence in the presence of noise is essential for
the development of quantum devices. Here the Rigetti quantum computing platform
was used to test different dynamical decoupling sequences. The performance of
the sequences was characterized by Quantum Process Tomography and analyzed
using the quantum channels formalism. It is shown that dynamical decoupling can
reduce qubit dephasing but cannot protect against spontaneous emission.
Furthermore, from process tomography results, it was also possible to conclude
that the action of dynamical decoupling cannot be understood as a simple
modification of the qubit coherence time. It is also shown here that the
performance of dynamical decoupling on the Rigetti's qubits is limited by pulse
imperfections. However, the performance can be improved using robust dynamical
decoupling, i.e. sequences that are robust against experimental imperfections.
The sequences tested here outperformed previous dynamical decoupling sequences
tested in the same platform.
