Mitigation of ZZ Coupling on Fluxonium-based Multiqubit Systems

Due to their scalability, high gate fidelities, and fast gate times, superconductor circuits are considered good candidates for the development of a quantum processor. This quantum computing approach is often one of the top choices in Industry. In the field of superconducting quantum computing there has been significant progress in reducing single-qubit gate errors however, two-qubit gates still suffer from error rates that are considerably higher. One of the main sources for these error rates is the unwanted ZZ interaction that arises when two qubits are coupled to generate entanglement. This unwanted ZZ quantum crosstalk is responsible for error rates in qubit systems. In recent years it has been shown that the ZZ coupling can be eliminated [1,2], achieving high-fidelity operations. In this talk, we will analyze the reduction of ZZ coupling in multi-fluxonium systems with capacitive interactions between qubits. We will theoretically show that with an optimal choice of fluxonium macroscopic parameters the ZZ quantum crosstalk can be reduced. We further demonstrate that microwave off-resonant drive of the multi-fluxonium system reduces ZZ crosstalk as it was demonstrated for a two fluxonium circuit [2].

[1] K.X Wei et al. arXiv:2106.00675v1

[2] H. Xiong et al. Phys. Rev. Research 4, 023040