Figure 2

Deconvolution of decoherence noise both on a simulator and the real quantum device Aspen-9 by Rigetti. (a) Scheme of the quantum circuit used in the simulations and runs on the actual quantum device. A qubit is prepared in the superposition state and then it is left to decohere for a certain amount of time, dependent on the number m of identities in the circuit. Eventually the qubit is measured in the x basis to estimate the expectation value \(\sigma _{x}\). (b) Scheme of Aspen-9, the real quantum device by Rigetti used to run the quantum circuit. (c) Simulation of the decoherence noise for dephasing (p) and damping (γ) intensities equal to those characterizing qubit 25 of Aspen-9, with gate duration of 40 ns. For comparison, the effect of the action of these channels alone is also showed. Using the deconvolution formulas for decoherence noise (55), it is possible to mitigate the decay caused by the noise, and recover the ideal result. Each expectation value is estimated evaluating the mean over \(n_{\text{shots}} = 2048\) measurement outcomes, and the error bars showed are the statistical error of the mean. (d) Results obtained from running the circuit on qubit 4 of Aspen-9, characterized by relaxation times \(T_{1} = 17.43\cdot 10^{-6}\text{ s}\) and \(T_{2} = 10.67\cdot 10^{-6}\text{ s}\), with \(n_{\text{shots}} = 2048\), and the error bars are twice the error of the mean. See main text for comments on the results. (e) Results obtained from running the circuit on qubit 25 of Aspen-9, characterized by relaxation times \(T_{1} = 35.91\cdot 10^{-6}\text{ s}\) and \(T_{2} = 25.11\cdot 10^{-6}\text{ s}\), with \(n_{\text{shots}} = 1024\). Also in this case the error bars are equals to twice the error of the mean. See main text for comments on the results