Process tomography of Robust Dynamical Decoupling in Superconducting Qubits

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 does not merely change the coherence times of the qubit, instead, it creates an effective environment. As in early dynamical decoupling experiments, it is also shown here that the performance of the sequences can be limited by pulse imperfections. However, the performance can be improved using robust sequences, i.e. dynamical decoupling sequences that are robust against experimental imperfections.