QSweep: Pulse-Optimal Single-Qudit Synthesis

Abstract

The synthesis of single-qudit unitaries has mainly been understudied, resulting in inflexible and non-optimal analytical solutions, as well as inefficient and impractical numerical solutions. To address this challenge, we introduce QSweep, a guided numerical synthesizer that produces pulse-optimal single-qudit decompositions for any subspace gateset, outperforming all prior solutions. When decomposing ququart gates, QSweep created circuits 4100x (up to 23500x) faster than QSearch with an average of 7.9 fewer pulses than analytical solutions, resulting in an overall 1.54x and 2.36x improvement in experimental single-qutrit and ququart gate fidelity as measured by randomized benchmarking.