High-fidelity quantum gates on spin-qubit registers in diamond

Spins associated with solid-state color centers are promising for quantum networks and distributed quantum computing [1]. Increasing the size of quantum networks requires high-fidelity control of the spin-qubit register within each node. In this work, we use gate set tomography [2] to characterize and optimize gates on electron and nuclear spin-qubits of a nitrogen-vacancy (NV) center in diamond.



We first use a model system in an isotopically purified diamond (0.01% ¹³C isotope) to obtain ideal case single-qubit gate fidelities of 99.999(1)% and two-qubit gate fidelities exceeding 99.9%. We then discuss our progress towards larger qubit registers by moving to a diamond sample with a natural abundance ¹³C (1.1%) and using the ¹³C spins as qubits. We discuss the challenges for high gate fidelity such as crosstalk and the effect of the spin bath. This work represents a benchmark for quantum information applications using NV centers in diamond, as well as other electron-nuclear spin systems.



[1] D. D. Awschalom et al. Quantum technologies with optically interface solid-state spins. Nature Photonics 12, 516 (2018)

[2] E. Nielsen et al. Gate Set Tomography. Quantum 5, 557 (2021)