Closed-loop optimization of fast trapped-ion shuttling with sub-quanta excitation

TL;DR

This paper demonstrates a closed-loop optimization method for fast ion shuttling in trapped-ion quantum computers, achieving high-speed transport with minimal motional excitation and robustness against phase variations.

Contribution

It introduces a closed-loop control technique to optimize ion transport waveforms, reducing motional excitation during high-speed shuttling in trapped-ion systems.

Findings

Achieved ion transport at 0.5 electrodes/μs with 0.36±0.08 quanta excitation

Waveforms are robust against phase of secular motion

Sub-quanta excitation independent of phase, eliminating need for additional impulses

Abstract

Shuttling ions at high speed and with low motional excitation is essential for realizing fast and high-fidelity algorithms in many trapped-ion based quantum computing architectures. Achieving such performance is challenging due to the sensitivity of an ion to electric fields and the unknown and imperfect environmental and control variables that create them. Here we implement a closed-loop optimization of the voltage waveforms that control the trajectory and axial frequency of an ion during transport in order to minimize the final motional excitation. The resulting waveforms realize fast round-trip transport of a trapped ion across multiple electrodes at speeds of $0.5$ electrodes/$\mu$s ($35 \text{m/s}$) with a maximum of $0.36\pm0.08$ quanta gain. This sub-quanta gain is independent of the phase of the secular motion at the distal location, obviating the need for an electric field impulse or time delay to eliminate the coherent motion