📝 SummarXiv

Abstract

We demonstrate a general protocol for realizing fast high-fidelity multi-qubit gates, through dynamical decoupling (DD) pulse sequences applied to a central qubit coupled to target qubits. This way, we are able to control the states of the target qubits by leveraging their intrinsic interaction with the central qubit, eliminating the need for slow error-prone direct control. The DD-gate protocol is developed and experimentally implemented within two distinct frameworks: a hardware-agnostic model with minimal assumptions, benchmarked within a general-purpose digital quantum simulator given by the IBMQ; and an experimentally realistic case with nitrogen-15 vacancy center ($^{15}$NV) in diamond. Likewise, we are able to thoroughly characterize the quantum mechanical dynamics behind the multi-qubit gates within IBMQ, without many of the experimental constraints faced by other quantum systems. While at the same time, we establish the protocol for the $^{15}$NV system, considering its specific properties. The DD-gates with $^{15}$NVs can represent a significant reduction in gate times and improved technological scalability, compared to current methods of target qubit control using dynamical decoupling. In addition, we propose a simple application of the method for high-efficiency polarization generation of the $^{15}$N nuclear spin. All experimental findings are supported by comprehensive open-source simulations in the two distinct frameworks. This work provides a robust hardware-agnostic strategy for quantum control, which can be implemented with arbitrary systems that fit the central-target qubits description. Thus, marking an essential step in technological scalability of future quantum devices.