Fault-Tolerant Directional Couplers for State Manipulation in Silicon Photonic-Integrated Circuits

TL;DR

This paper presents high-fidelity, fault-tolerant directional couplers for quantum gates in silicon photonic circuits, using detuning-modulated composite segments to improve robustness against fabrication errors and wavelength variations.

Contribution

It introduces a novel scheme of detuning-modulated composite segments for directional couplers, enhancing stability and fidelity in integrated quantum photonic circuits.

Findings

Demonstrated high-fidelity directional couplers with improved wavelength tolerance

Designed couplers with reduced sensitivity to fabrication errors

Showed potential for scalable quantum photonic architectures

Abstract

Photonic integrated circuits play a central role in current and future applications such as communications, sensing, ranging, and information processing. Photonic quantum computing will also likely require an integrated optics architecture for improved stability, scalability, and performance. Fault-tolerant quantum computing mandates very accurate and robust quantum gates. In this work, we demonstrate high-fidelity directional couplers for single-qubit gates in photonic integrated waveguides, utilizing a novel scheme of detuning-modulated composite segments. Specific designs for reduced sensitivity to wavelength variations and real-world geometrical fabrication errors in waveguides width and depth are presented. Enhanced wavelength tolerance is demonstrated experimentally. The concept shows great promise for scaling high fidelity gates as part of integrated quantum optics architectures.