  We experimentally demonstrate a virtual two-qubit gate and characterize it
using quantum process tomography~(QPT). The virtual two-qubit gate decomposes
an actual two-qubit gate into single-qubit unitary gates and projection gates
in quantum circuits for expectation-value estimation. We implement projection
gates via mid-circuit measurements. The deterministic sampling scheme reduces
the number of experimental circuit evaluations required for decomposing a
virtual two-qubit gate. We also apply quantum error mitigation to suppress the
effect of measurement errors and improve the average gate fidelity of a virtual
controlled-$Z$ (CZ) gate to $f_{\rm av} = 0.9938 \pm 0.0002$. Our results
highlight a practical approach to implement virtual two-qubit gates with high
fidelities, which are useful for simulating quantum circuits using fewer qubits
and implementing two-qubit gates on a distant pair of qubits.
