Cross Waveguide Design for Color-Centers in Diamond for Photonic Quantum Computing

TL;DR

This paper presents a novel cross waveguide design for diamond-based color centers, enabling efficient photon collection and excitation in photonic quantum circuits through optimized chiplet and receptor components.

Contribution

It introduces a simple methodology for optimizing cross waveguide chiplets and receptors, enhancing integration and performance for quantum photonic applications.

Findings

Achieves excitation-to-emission conversion >5.4%

Crosstalk less than -40 dB

Bandwidth of 160 nm

Abstract

Color centers in diamond are a promising platform for quantum computing applications because of their optical and spin properties. However, diamond presents some technological challenges that limit its use in complex or large photonic circuits. To mitigate these limitations, it is technically effective to separate the smallest possible diamond photonic structures or chiplet containing the color center(s) from the rest of the circuit, which is fabricated on another material platform, and then heterogeneously integrate them. Considering efficient excitation and photon collection from waveguide-coupled color centers, we design a cross waveguide as the primary component of our chiplet to access the color centers, channeling excitation and emitted photons into different waveguides, and connecting the structure to the other components of the photonic circuit. The chiplet containing the cross waveguide and supporting structures requires careful optimization of each subcomponent. The receptor's design is also critical for optimal signal transmission. In this paper, we develop a simple but efficient methodology to optimize the main components constituting both the chiplet and the receptor for their synergistic operation. The designed structure has an excitation-to-emission conversion of more than 5.4%, crosstalk of less than -40 dB, a working bandwidth of 160 nm, fabrication feasibility and tolerance within the limits of modern nanofabrication, and a mechanical solid structure with a footprint of less than 2000 $\mu$m