Suppressing Coherent Two-Qubit Errors via Dynamical Decoupling

TL;DR

This paper demonstrates the use of dynamical decoupling techniques to significantly suppress two-qubit dephasing errors in superconducting quantum devices, improving coherence times and robustness of multi-qubit gates.

Contribution

It introduces a framework for mitigating two-qubit errors using dynamical decoupling on tunable couplers in superconducting qubits, advancing quantum gate fidelity.

Findings

Pure-dephasing time increased by up to 14 times with robust sequences.

Results align with noise models from room-temperature circuits.

Framework for developing error-robust gates and sequences established.

Abstract

Scalable quantum information processing requires the ability to tune multi-qubit interactions. This makes the precise manipulation of quantum states particularly difficult for multi-qubit interactions because tunability unavoidably introduces sensitivity to fluctuations in the tuned parameters, leading to erroneous multi-qubit gate operations. The performance of quantum algorithms may be severely compromised by coherent multi-qubit errors. It is therefore imperative to understand how these fluctuations affect multi-qubit interactions and, more importantly, to mitigate their influence. In this study, we demonstrate how to implement dynamical-decoupling techniques to suppress the two-qubit analogue of the dephasing on a superconducting quantum device featuring a compact tunable coupler, a trending technology that enables the fast manipulation of qubit--qubit interactions. The pure-dephasing time shows an up to ~14 times enhancement on average when using robust sequences. The results are in good agreement with the noise generated from room-temperature circuits. Our study further reveals the decohering processes associated with tunable couplers and establishes a framework to develop gates and sequences robust against two-qubit errors.