Crosstalk-Robust Dynamical Decoupling for Bipartite-Topology Quantum Processors

TL;DR

This paper presents a modified dynamical decoupling protocol that enhances robustness against static $ZZ$ crosstalk in bipartite-topology quantum processors, leading to significant fidelity improvements on superconducting qubit devices.

Contribution

The authors introduce a pulse-timing modification to dynamical decoupling sequences that effectively suppresses static $ZZ$ crosstalk in two-colorable qubit topologies, supported by theoretical analysis and experimental validation.

Findings

Achieved at least 3x improvement in fidelity decay rate on IBM superconducting qubits.

Demonstrated robustness of the method across various sequences and devices.

Found reduced impact of $ZZ$ errors in tunable-coupler architectures, with fixed-coupler devices outperforming when protected by DD.

Abstract

We introduce a protocol that modifies dynamical decoupling (DD) sequences to be robust to static $ZZ$ crosstalk when implemented with bounded control on two-colorable qubit topologies. The protocol, which relies on modifications to the pulse timing, can be applied to any sequence with equidistant $\pi$-pulses. We motivate the method theoretically via suppression conditions identified through time-dependent perturbation theory. Theoretical findings are supported by demonstrations of widely studied sequences on several superconducting qubit devices offered by the IBM Quantum Platform. Using up to 20 qubits on fixed-coupler devices, we observe at least a $3\times$ improvement in the fidelity decay rate via our approach when compared to non-robust DD variants. In addition, we leverage our approach to assess the impact of $ZZ$ errors on tunable-coupler devices. We find that $ZZ$-robust sequences perform nearly equivalent to non-robust DD, affirming the reduced impact of such errors in a tunable-coupler architecture. Nevertheless, our demonstrations indicate that fixed-coupler devices, when subject to DD-protection, can outperform tunable-coupler devices. Our method broadens the scope of practical DD protocols: with modest overhead and a reasonable constraint on the qubit topology, the method attains significant performance improvements on modern quantum computing devices.