Co-design of quantum computing devices with optimal control

When exploring operating regimes for quantum devices, often specific properties like noise resistance are selected based on previous experience or intuition, resulting in designs like the Transmon, a widely adopted design for superconducting qubit. In the current NISQ era, there is a demand for functional quantum devices to solve relevant computational problems, which motivates a more utilitarian perspective on device design: The goal is to have a device that is employed to run a given algorithm with state-of-the-art performance.

In this work, we assume this perspective and use optimal control tools to derive the gates required by a toy two-qubit algorithm consisting of simultaneous single-qubit gates followed by an entangling gate and, in tandem, explore the model space of superconducting quantum computer design, from dispersively coupled to strongly interacting qubits, to maximize gate fidelity. The use of perfect entangler theory provides a flexibility to the search for a two-qubit gate on a given platform and enables a comparison between designs with different entangling mechanisms, e.g. CPHASE and √iSWAP.