Towards high-fidelity two-qubit gates on strongly coupled fluxonium qubits

Microwave activated two-qubit gate schemes for fluxonium qubits have been demonstrated using the transitions outside computational space [1,2], where the gate fidelity is limited by the decoherence of these higher levels. Two-qubit gate using only computational states of fluxoniums was also achieved recently with high fidelity [3]. Here we demonstrate the implementation of controlled-Z gate utilizing strong coupling between two fluxoniums, where the large induced static ZZ term can still be cancelled. This scheme for high fidelity gate operation can benefit the development of fluxonium based quantum processors and universal quantum computation.

[1] Physical Review X 11(2) (2021): 021026

[2] arXiv preprint arXiv:2103.04491 (2021)

[3] arXiv preprint arXiv:2204.11829 (2022)