Quantum optimization experiments with advanced mixers and controls*

Modern quantum optimization methods feature quantum circuits with partially-ordered modular levels, such as the Quantum Alternating Operator Ansatz¹. For QAOA to work in practice on NISQ devices, it must extract value from quantum effects despite daunting fidelity degradation due to noise². Our experiments on a Rigetti processor, featuring these kind of algorithms, employ calibrated parametric CZ³ and XY^4,5 gates, as well as analog-controlled phases between qubit pairs programmed with a low-level pulse design language (Quilt). We show experimental benchmark results on a 32-qubit chip for circuits related to hard-constrained scheduling problems as well as MaxCut.

¹Hadfield et al. 2019. From the quantum approximate optimization algorithm to a quantum alternating operator ansatz. Algorithms 12(2)
²Marshall et al. 2020. Characterizing local noise in QAOA circuits. arXiv:2002.11682
³Caldwell et al. 2018. Parametrically activated entangling gates using transmon qubits. PRApplied 10(3):034050
⁴Abrams et al. 2019. Implementation of the XY interaction family with calibration of a single pulse. arXiv:1912.04424
⁵Wang et al. 2020. XY mixers: Analytical and numerical results for the quantum alternating operator ansatz. PRA 101(1), 012320