Initial Correlations and Time-Retarded Noise in Dynamical Decoupling Schemes for Superconducting Qubits
One of the simplest and least resource-intensive methods to suppress decoherence for superconducting qubit operations, namely, dynamical decoupling (DD), is investigated for a broad range of realistic noise sources with time-retarded feedback. By way of example, the Carr-Purcell-Meiboom-Gill (CPMG) sequence is analyzed in a numerically rigorous manner accounting also for correlations between qubit and environment. Since experimentally noise sources are characterized through spectral densities, we adopt the spin-boson model as a suitable platform to describe the qubit dynamics under DD for a given spectral density J(ω)∝ωs. To cover a broad range of noise sources, the spectral exponent s is varied from s=1 (Ohmic bath) to a substantially small value 0