Dissipative Dynamics of Graph-State Stabilizers with Superconducting Qubits

TL;DR

This study combines experimental and numerical methods to analyze the dissipative dynamics of multipartite entangled states in superconducting qubits, emphasizing the importance of charge-parity fluctuations and enabling scalable simulations for quantum error correction.

Contribution

We introduce a scalable numerical model accounting for charge-parity fluctuations, validated by experiments on up to 12 qubits, advancing understanding of stabilizer dynamics and error mitigation.

Findings

Charge-parity fluctuations significantly affect qubit dynamics.

Numerical simulations agree well with experimental data.

Dynamical decoupling mitigates two-qubit crosstalk.

Abstract

We study experimentally and numerically the noisy evolution of multipartite entangled states, focusing on superconducting-qubit devices accessible via the cloud. We find that a valid modeling of the dynamics requires one to properly account for coherent frequency shifts, caused by stochastic charge-parity fluctuations. We introduce an approach modeling the charge-parity splitting using an extended Markovian environment. This approach is numerically scalable to tens of qubits, allowing us to simulate efficiently the dissipative dynamics of some large multiqubit states. Probing the continuous-time dynamics of increasingly larger and more complex initial states with up to 12 coupled qubits in a ring-graph state, we obtain a good agreement of the experiments and simulations. We show that the underlying many-body dynamics generate decays and revivals of stabilizers, which are used extensively in the context of quantum error correction. Furthermore, we demonstrate the mitigation of two-qubit coherent interactions (crosstalk) using tailored dynamical decoupling sequences. Our noise model and the numerical approach can be valuable to advance the understanding of error correction and mitigation and invite further investigations of their dynamics.