Abstract The emergence of noisy intermediate-scale quantum processors marked a pivotal stage in quantum computing, enabling the first demonstrations of quantum computational advantage despite limitations in qubit count, connectivity, and gate fidelity. Among the earliest and most accessible NISQ platforms were the IBM Quantum $$^\texttt {TM}$$ TM computers, which provided an open testbed for algorithm development, benchmarking, and error mitigation. Crucially, many of these pioneering quantum computers have since been retired, rendering their performance records fragmented and at risk of permanent loss. This work presents a comprehensive benchmarking study of these early IBM quantum computers, documenting their architectural layouts, qubit connectivity, native gate sets, coherence properties, effective Hamiltonians, control mechanisms, error rates, and operational performance. We reconstruct the operational profiles of these quantum computers and highlight the trends, trade-offs, and limitations that characterized superconducting quantum hardware in the NISQ era. This study establishes a historical baseline for assessing progress in quantum hardware development, offering essential guidance on error scaling, coherence limitations, and architectural trade-offs for designing next-generation quantum hardware. These insights directly inform superconducting quantum architecture design, compilation strategies, and error-resilient algorithms on the path toward fault-tolerant quantum computation.
Abstract The emergence of noisy intermediate-scale quantum processors marked a pivotal stage in quantum computing, enabling the first demonstrations of quantum computational advantage despite limitations in qubit count, connectivity, and gate fidelity. Among the earliest and most accessible NISQ platforms were the IBM Quantum TM TM computers, which provided an open testbed for algorithm development, benchmarking, and error mitigation. Crucially, many of these pioneering quantum computers have since been retired, rendering their performance records fragmented and at risk of permanent loss. This work presents a comprehensive benchmarking study of these early IBM quantum computers, documenting their architectural layouts, qubit connectivity, native gate sets, coherence properties, effective Hamiltonians, control mechanisms, error rates, and operational performance. We reconstruct the operational profiles of these quantum computers and highlight the trends, trade-offs, and limitations that characterized superconducting quantum hardware in the NISQ era. This study establishes a historical baseline for assessing progress in quantum hardware development, offering essential guidance on error scaling, coherence limitations, and architectural trade-offs for designing next-generation quantum hardware. These insights directly inform superconducting quantum architecture design, compilation strategies, and error-resilient algorithms on the path toward fault-tolerant quantum computation.
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.
Quantum computing has transitioned from a theoretical curiosity to an emerging technological paradigm with demonstrable computational advantages in specific problem domains. This paper presents a comprehensive review of current advances in quantum computing hardware, software, and near-term applications within the Noisy Intermediate-Scale Quantum (NISQ) era. We examine the architectural evolution of leading quantum platforms, including superconducting, trapped-ion, and photonic systems, analyzing their qubit counts, gate fidelities, and coherence times. The paper evaluates key quantum algorithms Shor's factoring algorithm [1], Grover's search algorithm [2], the Variational Quantum Eigensolver (VQE) [3], and the Quantum Approximate Optimization Algorithm (QAOA) [4] in the context of their practical applicability to real-world problems. We further discuss the milestone of quantum computational advantage demonstrated by Google's Sycamore processor [5] and IBM's ambitious hardware roadmap toward fault-tolerant quantum computing [6]. Our analysis reveals that while universal fault-tolerant quantum computing remains a long-term objective, NISQ-era devices are already yielding valuable results in quantum chemistry simulation, combinatorial optimization, and quantum machine learning. We conclude by identifying the critical challenges—error correction, scalability, and algorithm design that must be addressed to realize the full potential of quantum computing.
The transition from classical to quantum computation marks a shift from deterministic binary logic to a probabilistic, entanglement‑driven framework able to address problems beyond classical reach. Today’s Noisy Intermediate ‑ Scale Quantum era features devices that lack full error correction yet already point toward larger, modular systems designed for fault‑tolerant operation. This paper examines the evolving paradigm shift from classical and NISQ ‑ era machines toward practical fault‑tolerant quantum computing, focusing on how advances in physical qubit technologies, control architectures, and error‑correction strategies are converging to bridge noisy prototypes and scalable, useful machines. We synthesize insights from historical semiconductor scaling trends, contemporary roadmaps from leading institutions and industry, and emerging modular designs with real‑time error decoding. Our analysis shows that while challenges around decoherence, connectivity, and classical co‑processing remain, coordinated progress in hardware, control, and software is laying a coherent foundation for future quantum platforms. The work concludes that quantum computing is maturing into a strategically significant paradigm, poised to redefine the limits of computation in simulation, optimization, and secure communication.
Quantum computing has progressed from early demonstrations across superconducting, trapped ion, photonic, and spin-based platforms to increasingly integrated systems. However, transitioning from the noisy intermediate-scale quantum (NISQ) era to robust, fault tolerant implementations remain a central challenge. This paper presents a systematic review and synthesis of practical quantum computing, encompassing experimental advances, integrated photonics, error correction breakthroughs, software stack evolution, benchmarking practices, algorithmic readiness, and socio-technical dimensions. We critically assess current limitations and highlight emerging directions, including integrated photonic modules with high fidelity interconnects, real time decoders for surface code logical qubits, and hardware aware compiler strategies. Our analysis is grounded in peer-reviewed experimental data and model-based evaluations. Key findings include demonstrated logical error suppression via increased code distance, scalable photonic module prototypes, and refined resource estimates for cryptanalytic and simulation tasks. This paper concludes with a structured research agenda for 2025–2030, proposing four priority thrusts such as hardware QEC co design, reproducible cross platform benchmarking, modular/distributed architectures, and quantum networking with governance frameworks. This evidence based roadmap aims to align researchers and practitioners toward actionable milestones on the path to practical quantum computing.
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.
The maturation of quantum computing from theoretical physics to engineering reality presents a complex landscape for stakeholders navigating the transition from Noisy Intermediate-Scale Quantum (NISQ) devices toward Fault-Tolerant Quantum Computation (FTQC). This report provides a comprehensive, technically rigorous analysis of the current quantum ecosystem, examining the hardware mosaic of leading qubit modalities—superconducting circuits, trapped ions, neutral atoms, and silicon spin qubits—and evaluating them against operational metrics, including coherence times, gate fidelities, and cryogenic infrastructure requirements. We dissect the full software stack, differentiating the near-term utility of error mitigation techniques such as Zero-Noise Extrapolation (ZNE) from the long-term necessity of Quantum Error Correction (QEC) and the milestone of logical qubit break-even. The analysis benchmarks hybrid algorithms (VQE, QAOA) and circuit knitting strategies against current cloud-accessible hardware performance, while also addressing the imminent non-computational impact of PostQuantum Cryptography (PQC) migration. Experimental data synthesised from leading vendor roadmaps and pre-print literature indicate that superconducting platforms currently lead in gate speed (nanosecond regime) but face crosstalk scaling challenges beyond 1,000 qubits. In contrast, trapped-ion and neutral-atom architectures demonstrate superior connectivity and coherence. The report concludes with a grounded, evidence-based five-year projection, identifying high-value vertical use cases in pharmaceuticals and finance, and providing a strategic framework for enterprises to separate quantum hype from tangible commercial opportunity. Future research directions include the realisation of low-overhead Quantum LDPC codes and the development of modular photonic interconnects to scale beyond single-chip architectures.