Design and optimal control of superconducting qubits to achieve quantum entangling gate speed limits

Abstract

The finite coherence times of quantum computers necessitates fast single and two-qubit gates. While single-qubit gates can in theory be arbitrarily fast, the speed of two-qubit gates is dependent on the interaction strength. For a static ZZ interaction the speed of several important gates have been analytically determined. Here we experimentally demonstrate reaching those speed limits on two superconducting transmon qubits with a fixed capacitive coupling. We also present a numerical optimizer capable of producing arbitrary speed-limited gates with high fidelity. Finally, we present a software suite for fully integrating and automating superconducting qubit design, simulation, and fabrication layout in a modular and extensible framework.