  We propose to increase the fidelity of two-qubit resonator-induced phase
gates in circuit QED by the use of narrowband single-mode squeezed drive. We
show that there exists an optimal squeezing angle and strength that erases
qubit 'which-path' information leaking out of the cavity and thereby minimizes
qubit dephasing during these gates. Our analytical results for the gate
fidelity are in excellent agreement with numerical simulations of a cascaded
master equation that takes into account the dynamics of the source of squeezed
radiation. With realistic parameters, we find that it is possible to realize a
controlled-phase gate with a gate time of 200 ns and average infidelity of
$10^{-5}$.
