Superconducting transmon qubits are of great interest for quantum computing and quantum simulation. A key component of quantum chemistry simulation 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. We use the local invariants of the evolution operator in SU(4) to develop a method of constructing pulse protocols, which allows for the continuous tuning of the phase. We find CPHASE fidelities of more than 0.999 and gate times as low as 100 ns.
@article{arxiv.1903.00969,
title = {Microwave-based Arbitrary CPHASE Gates for Transmon Qubits},
author = {George S. Barron and F. A. Calderon-Vargas and Junling Long and David Pappas and Sophia E. Economou},
journal= {arXiv preprint arXiv:1903.00969},
year = {2020}
}