A Comparative Review of Quantum Bits: Superconducting, Topological, Spin, and Emerging Qubit Technologies

Eisuke Abe, Shuhei Tamate

Arun Govindankutty

The pursuit of a universal, fault-tolerant quantum computer has transformed quantum computing from a predominantly theoretical discipline into a rapidly diversifying hardware ecosystem. This review presents a comprehensive and technically grounded analysis of the principal physical qubit modalities: superconducting circuits, trapped ions, photonic platforms, neutral atoms, semiconductor spin qubits, and topological approaches, focusing on their underlying operating principles, performance characteristics, and system-level constraints. We examine how these qubit technologies are embedded within scalable quantum processor architectures, including control and readout infrastructures, connectivity topologies, and quantum error correction strategies. The review provides a comparative study of key performance metrics, such as coherence times, gate fidelities, error rates, and scalability, reveals fundamental trade-offs between speed, robustness, and operational complexity that shape distinct technological roadmaps and target applications. We further highlight the ongoing transition from noisy intermediate-scale quantum (NISQ) devices toward architectures centred on logical qubits, driven by advances in materials engineering, precision control, and quantum information theory. Together, these developments sketch the emerging routes toward fault-tolerant quantum computing and practical quantum advantage, while offering readers a coherent entry point and reference guide to the current quantum hardware landscape.

John L. Clarke, Frank K. Wilhelm

Jordan Y. Arpilleda

The study delves into the transformative journey of electronics technology. Through a historical overview, it traces the evolution of miniaturization trends and explores the emergence of quantum bits (qubits) with their unique properties of superposition and entanglement. Comparative analysis reveals the advantages of quantum systems in addressing complex challenges. Expert interviews provide practical insights, while the review of experimental findings offers empirical validation of qubitbehavior. Challenges in qubit stability and quantum-classical integration are discussed, emphasizing the crucial role of empirical research in shaping the trajectory of electronics technology.

Michel Devoret

Jincheng Zhang

This paper proposes a novel quantum computing architecture designed based on fundamental physical laws. The architecture addresses limitations inherent in current quantum computing approaches, primarily those utilizing superconducting qubits. The core of the design leverages emerging quantum bit technologies, specifically topological qubits and photonic qubits, to achieve enhanced fidelity and scalability. We argue that by moving beyond the established paradigm of superconducting qubits, and embracing physically grounded approaches, we can significantly advance the performance and practicality of quantum computation. This document details the architectural components, outlines the key technological considerations, and presents a theoretical framework for a fundamentally robust quantum computing system. The focus is on building a system that aligns with known physical constraints, offering a more reliable path toward realizing the full potential of quantum computation. ---