An automated geometric space curve approach for designing dynamically corrected gates

Abstract The noisy nature of quantum hardware necessitates the implementation of high-fidelity quantum gates in a noise-insensitive manner. While there exist many powerful methods for designing dynamically corrected gates (DCGs), they often use a single cost function to simultaneously achieve a target gate and suppress noise. This can lead to unnecessary tradeoffs that lower gate fidelities and complicate the discovery of globally-optimal solutions. Here, we present a method for single-qubit DCGs called Bézier Ansatz for Robust Quantum (BARQ) control to address these challenges. Rather than numerically optimizing the controls directly, BARQ instead makes use of the Space Curve Quantum Control formalism in which the quantum evolution is mapped to a geometric space curve. In the formulation used by BARQ, the boundary conditions of the space curve dictate the target gate while its shape determines the gate’s noise sensitivity. We eliminate the aforementioned tradeoffs by employing a control-point parameterization that allows the target gate to be fixed upfront and use numerical optimization only for noise-robustness. BARQ introduces a global perspective into the control landscape and provides ample freedom to design experimentally friendly and robust control pulses. The pulse design is facilitated through the developed software package qurveros .