Compact optical waveform generator with digital feedback

TL;DR

This paper introduces a compact optical waveform generator with digital feedback that precisely shapes laser pulses for quantum operations, improving fidelity by real-time correction of distortions in sub-microsecond pulses.

Contribution

It presents a novel integrated device combining amplitude and phase modulation with real-time pulse shape correction for quantum laser pulses.

Findings

Successfully generates shaped laser pulses down to 180 ns

Achieves high-fidelity quantum gate operations with minimal feedback iterations

Demonstrates real-time correction of pulse distortions

Abstract

A key requirement for quantum technologies based on atoms, ions, and molecules, is the ability to realize precise phase- and amplitude-controlled quantum operations via coherent laser pulses. However, for generating pulses on the sub-microsecond timescale, the characteristics of the optical and electronic components can introduce unwanted distortions that have a detrimental effect on the fidelity of quantum operations. In this paper, we present a compact arbitrary waveform generator that integrates a double-pass acousto-optic modulator for user-specified laser amplitude and phase modulations. Additionally, the module integrates an optical heterodyne detector to extract the precise laser pulse shape in real-time. The measured pulse shape is then fed into a digital feedback loop used to estimate the complex-valued transfer function and pre-distorted input pulses. We demonstrate the performance by generating shaped laser pulses suitable for realizing quantum logic gates with durations down to 180\,ns, requiring only a small number of feedback iterations.