As a key approach to augment Moores Law scaling, 3D integration technologies have enabled small form factor, low cost, diverse, modular and flexible assembly of integrated circuits in the semiconductor industry. It is therefore essential to adopt these technologies to the quantum computing devices which are at the nascent stage and generally require large scale integration to be particle. In this review, we focus on four popular quantum bit (qubit) candidates (trapped ion, superconducting circuit, silicon spin and photon) which are encoded by distinct physical systems but all intrinsically compatible with advanced CMOS fabrication process. We introduce the specific scalability bottlenecks of each qubit type and present the current solutions using 3D integration technologies. We evaluate and classify these technologies into three main categories based on the hierarchy. A brief discussion regarding to the thermal management is also provided. We believe this review serves to provide some useful insights on the contributions of interconnect, integration and packaging to the field of quantum computing where rapid development is ongoing.
As a key approach to augment Moores Law scaling, 3D integration technologies have enabled small form factor, low cost, diverse, modular and flexible assembly of integrated circuits in the semiconductor industry. It is therefore essential to adopt these technologies to the quantum computing devices which are at the nascent stage and generally require large scale integration to be particle. In this review, we focus on four popular quantum bit (qubit) candidates (trapped ion, superconducting circuit, silicon spin and photon) which are encoded by distinct physical systems but all intrinsically compatible with advanced CMOS fabrication process. We introduce the specific scalability bottlenecks of each qubit type and present the current solutions using 3D integration technologies. We evaluate and classify these technologies into three main categories based on the hierarchy. A brief discussion regarding to the thermal management is also provided. We believe this review serves to provide some useful insights on the contributions of interconnect, integration and packaging to the field of quantum computing where rapid development is ongoing.
Quantum chips form the foundational hardware for quantum computing, promising transformative impacts across optimization, secure communications, and artificial intelligence. This paper surveys five leading qubit implementations—superconducting circuits, neutral-atom arrays, trapped ions, photonic systems, and silicon-based quantum dots—highlighting their distinct operating principles, recent milestones, and inherent trade-offs. Superconducting platforms leverage mature microfabrication to achieve hundreds to thousands of qubits with rapid gate times but require millikelvin environments and face millisecond-scale coherence limits. Neutral-atom and ion-trap architectures offer exceptionally long coherence (seconds to hours) and high-fidelity operations, making them ideal for quantum memory and precision simulation, yet scaling remains constrained by control complexity. Photonic chips excel at room-temperature operation and quantum networking via entangled photons, though deterministic two-qubit gates and on-chip integration pose challenges. Silicon quantum dots promise CMOS compatibility and sub-microsecond spin coherence, but demand atomic-scale fabrication precision and advanced cryogenic control. We analyze the tension between qubit count, error rates, and engineering practicality, and discuss emerging solutions such as hybrid integration, advanced error-correction codes, and novel materials. Looking ahead, coordinated optimization across these platforms—combining fast superconducting processors, long-lived atomic memories, photonic interconnects, and scalable silicon arrays—will be critical to transition quantum chips from research prototypes to industrially viable systems that redefine computing, communications, and AI.
This paper presents a comprehensive review of quantum computing and the technological foundations of quantum processors. Quantum computing represents a transformative computational paradigm that leverages the fundamental principles of quantum mechanics—such as superposition, entanglement, and quantum interference—to solve complex problems that are intractable for classical computers. At the core of this paradigm lies the quantum processor, a specialized hardware system designed to initialize, control, and measure quantum bits (qubits) through precise gate operations and coherent interactions. The survey examines the essential theoretical concepts underlying quantum computation and provides a structured comparison of leading quantum processor platforms. Prominent architectures, including superconducting circuits, trapped-ion systems, and photonic implementations, are analyzed in terms of their physical mechanisms, scalability, coherence properties, and engineering challenges. Each platform offers distinct advantages and faces specific technical limitations related to noise, error correction, and fabrication complexity. In addition to reviewing hardware developments, this study highlights key obstacles in advancing quantum processors toward large-scale, fault-tolerant systems. Issues such as qubit stability, error mitigation, thermal management, and system integration are discussed to present a realistic perspective on current progress. Performance indicators including gate fidelity, coherence time, connectivity, and scalability are used to compare architectural approaches. The objective of this paper is to provide a clear and organized synthesis of recent advancements in quantum computing hardware, thereby offering researchers and practitioners a foundational reference to support continued innovation and development in this rapidly evolving field.
Quantum device fabrication and integration represent a critical frontier in the advancement of next-generation computing and communication technologies. This chapter provides an overview of the fundamental principles and processes involved in the fabrication of quantum devices, including superconducting qubits, semiconductor quantum dots, and spin-based devices. Key fabrication techniques such as advanced lithography, thin-film deposition, etching, and material characterization are discussed, with emphasis on the stringent requirements for precision, material purity, and defect control. The chapter also addresses challenges associated with integrating quantum devices with classical CMOS electronics, including cryogenic operation, interconnect design, scalability, and noise mitigation. By examining current fabrication approaches and integration strategies, this chapter highlights the technological barriers and emerging solutions shaping scalable quantum systems. The discussion offers readers a foundational understanding of how quantum devices are realized and integrated, bridging the gap between quantum physics and practical hardware implementation.
The superconducting qubit quantum computer is one of the most promising quantum computing architectures for large-scale integration due to its maturity and close proximity to the well-established semiconductor manufacturing infrastructure. From an education perspective, it also bridges classical microwave electronics and quantum electrodynamics. In this paper, we will review the basics of quantum computers, superconductivity, and Josephson junctions. We then introduce important technologies and concepts related to DiVincenzo's criteria, which are the necessary conditions for the superconducting qubits to work as a useful quantum computer. Firstly, we will discuss various types of superconducting qubits formed with Josephson junctions, from which we will understand the trade-off across multiple design parameters, including their noise immunity. Secondly, we will discuss different schemes to achieve entanglement gate operations, which are a major bottleneck in achieving more efficient fault-tolerant quantum computing. Thirdly, we will review readout engineering, including the implementations of the Purcell filters and quantum-limited amplifiers. Finally, we will discuss the nature and review the studies of two-level system defects, which are currently the limiting factor of qubit coherence time. DiVincenzo's criteria are only the necessary conditions for a technology to be eligible for quantum computing. To have a useful quantum computer, large-scale integration is required. We will review proposals and developments for the large-scale integration of superconducting qubit devices. By comparing with the application of electronic design automation (EDA) in semiconductors, we will also review the use of EDA in superconducting qubit quantum computer design, which is necessary for its large-scale integration.
Quantum device fabrication and integration represent a critical frontier in the advancement of next-generation computing and communication technologies. This chapter provides an overview of the fundamental principles and processes involved in the fabrication of quantum devices, including superconducting qubits, semiconductor quantum dots, and spin-based devices. Key fabrication techniques such as advanced lithography, thin-film deposition, etching, and material characterization are discussed, with emphasis on the stringent requirements for precision, material purity, and defect control. The chapter also addresses challenges associated with integrating quantum devices with classical CMOS electronics, including cryogenic operation, interconnect design, scalability, and noise mitigation. By examining current fabrication approaches and integration strategies, this chapter highlights the technological barriers and emerging solutions shaping scalable quantum systems. The discussion offers readers a foundational understanding of how quantum devices are realized and integrated, bridging the gap between quantum physics and practical hardware implementation.
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.