Microwave-based CPHASE gates for transmon qubits

Superconducting transmon qubits are of great interest for quantum simulation of quantum chemistry. A key component of these algorithms is breaking up the evolution into small steps, which naturally leads to the need for non-maximally entangling, arbitrary CPHASE gates. Here we design such microwave-based gates using an analytically solvable approach leading to smooth, simple pulses. Our protocol allows for the continuous tuning of the phase. We find CPHASE fidelities of more than 0.999 and typical gate times less than 100ns.