Fast, high precision dynamics in quantum optimal control theory

TL;DR

This paper introduces a novel quantum control framework that significantly accelerates optimization processes by using short-time propagators and Magnus expansion, enabling faster quantum device calibration.

Contribution

The paper presents a new theoretical approach replacing standard time propagation with Magnus expansion-based short-time propagators for faster quantum control optimization.

Findings

Achieves an order of magnitude speedup in quantum control optimization

Provides exact series terms and gradients for control calculations

Reduces computational cost of commutators and integrals

Abstract

Quantum optimal control theory is becoming increasingly crucial as quantum devices become more precise, but the need to quickly optimize these systems classically remains a significant bottleneck in their operation. Here we present a new theoretical quantum control framework for much faster optimization than the state of the art by replacing standard time propagation with a product of short-time propagators, each calculated using the Magnus expansion. The derived formulas for exact series terms and their gradients, based on earlier approximate integrals in a simulation setting, allow us to subsume the high cost of calculating commutators and integrals as an initial overhead. This provides an order of magnitude speedup for quantum control optimization.