Multi-qubit Dynamical Decoupling for Enhanced Crosstalk Suppression
Dynamical decoupling (DD) is one of the simplest error suppression methods,
aiming to enhance the coherence of qubits in open quantum systems. Moreover, DD
has demonstrated effectiveness in reducing coherent crosstalk, one major error
source in near-term quantum hardware, which manifests from two types of
interactions. Static crosstalk exists in various hardware platforms, including
superconductor and semiconductor qubits, by virtue of always-on qubit-qubit
coupling. Additionally, driven crosstalk may occur as an unwanted drive term
due to leakage from driven gates on other qubits. Here we explore a novel
staggered DD protocol tailored for multi-qubit systems that suppresses the
decoherence error and both types of coherent crosstalk. We develop two
experimental setups -- an "idle-idle" experiment in which two pairs of qubits
undergo free evolution simultaneously and a "driven-idle" experiment in which
one pair is continuously driven during the free evolution of the other pair.
These experiments are performed on an IBM Quantum superconducting processor and
demonstrate the significant impact of the staggered DD protocol in suppressing
both types of coherent crosstalk. When compared to the standard DD sequences
from state-of-the-art methodologies with the application of X2 sequences, our
staggered DD protocol enhances circuit fidelity by 19.7% and 8.5%,
respectively, in addressing these two crosstalk types.
Siyuan Niu Aida Todri-Sanial Nicholas T. Bronn