Learning Noise via Dynamical Decoupling of Entangled Qubits

Abstract

Noise in entangled quantum systems is difficult to characterize due to many-body effects involving multiple degrees of freedom. This noise poses a challenge to quantum computing, where two-qubit gate performance is critical. Here, we develop and apply multi-qubit dynamical decoupling sequences that characterize noise that occurs during two-qubit gates. In our superconducting system comprised of Transmon qubits with tunable couplers, we observe noise that is consistent with flux fluctuations in the coupler that simultaneously affects both qubits and induces noise in their entangling parameter. The effect of this noise on the qubits is very different from the well-studied single-qubit dephasing. Additionally, steps are observed in the decoupled signals, implying the presence of non-Gaussian noise.

arXiv comment5 pages, 4 figures

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• Assessing and Advancing the Potential of Quantum Computing: A NASA Case Study
• Modeling low- and high-frequency noise in transmon qubits with resource-efficient measurement
• Stabilizing two-qubit entanglement with dynamically decoupled active feedback
• High-Order Qubit Dephasing at Sweet Spots by Non-Gaussian Fluctuators: Symmetry Breaking and Floquet Protection
• Co-Designed Architectures for Modular Superconducting Quantum Computers
• Digital noise spectroscopy with a quantum sensor
• Open-loop quantum control of small-size networks for high-order cumulants and cross-correlations sensing
• Efficient learning and optimizing non-Gaussian correlated noise in digitally controlled qubit systems