  We propose a family of microwave-activated entangling gates on two
capacitively coupled fluxonium qubits. A microwave pulse applied to either
qubit at a frequency near the half-frequency of the $|00\rangle - |11\rangle$
transition induces two-photon Rabi oscillations with a negligible leakage
outside the computational subspace, owing to the strong anharmonicity of
fluxoniums. By adjusting the drive frequency, amplitude, and duration, we
obtain the gate family that is locally equivalent to the fermionic-simulation
gates such as $\sqrt{\rm SWAP}$-like and controlled-phase gates. The gate error
can be tuned below $10^{-4}$ for a pulse duration under 100 ns without
excessive circuit parameter matching. Given that the fluxonium coherence time
can exceed 1 ms, our gate scheme is promising for large-scale quantum
processors.
