The road to large-scale quantum computing is long and hard, with incremental advances paving the way. But the destination is in sight.
Quantum computing stands at the cutting edge of modern technology, promising transformative advances in everything from cryptography to drug discovery. At the heart of this revolution is the hardware—the physical machinery that enables quantum computers to operate. The global race to build quantum computers is not just about speed or size; it is a contest to master the most delicate and challenging aspects of quantum physics, making it one of the most exciting frontiers in science and engineering.
From silicon to superconductors: The evolution of quantum hardware
Silicon has long been the backbone of classical computers, powering everything from laptops to supercomputers. When physicists and engineers first ventured into the world of quantum computing, it was natural to start with what they knew best—silicon. Early quantum devices attempted to adapt silicon transistors, hoping to harness quantum effects like superposition and entanglement within a familiar framework. While these initial attempts provided important insights and proved that quantum behaviour could be observed in solid-state systems, the limitations of silicon soon became apparent. Issues such as decoherence—where quantum states lose their delicate properties—posed significant challenges, making it difficult to maintain stable qubits for practical computations.
Recognising the obstacles posed by silicon, researchers began exploring other materials that might better support quantum phenomena. This led to experiments with semiconductors such as gallium arsenide, and even exotic systems like trapped ions and photons. Each approach brought its own advantages and drawbacks. For instance, ion-trap and photonic quantum computers offered excellent coherence times and control, but scaling these systems for large-scale computations proved tricky. Meanwhile, semiconductor-based quantum dots allowed precise control over electrons, pointing towards new possibilities for qubit design.
As quantum computing research matured, superconducting materials emerged as a breakthrough technology. Superconductors are remarkable because, at extremely low temperatures, they allow electrical current to flow without any resistance. This property is ideal for creating quantum circuits, where maintaining quantum states with minimal interference is essential. Superconducting qubits, often crafted from materials like aluminium and niobium, are now the foundation of many leading quantum computers.
Superconducting qubits are typically implemented using devices such as Josephson junctions, which exploit quantum tunnelling effects to create robust, controllable qubits. These systems offer fast operation speeds and relatively straightforward integration with existing electronics, making them highly attractive for commercial and research purposes. Companies and institutions around the world—Google, IBM, and others—have built impressive quantum processors using superconducting technology, achieving milestones like quantum supremacy and demonstrating the practical potential of quantum computing.
Today, the landscape of quantum hardware is diverse and dynamic. While superconductors lead the way, research is ongoing into improving their performance and scalability. At the same time, silicon is enjoying a resurgence, with new approaches seeking to combine the familiarity of silicon manufacturing with quantum capabilities—so-called ‘silicon qubits’. Hybrid platforms, merging different materials and technologies, are also being developed to address the specific needs of various quantum applications.
The evolution from silicon to superconductors reflects the ingenuity of scientists and engineers in overcoming technical hurdles and pushing the boundaries of what is possible. As new materials and techniques continue to emerge, the future of quantum hardware looks both exciting and unpredictable, with the promise of ever more powerful machines on the horizon.
The progress made in the field of quantum computing
There is a lot happening globally to make quantum computing mainstream as soon as possible. Here’s a quick look at the progress made so far.
Matured silicon spin qubit fabrication
Foundries are now producing silicon spin qubits with unprecedented uniformity and yield. This is achieved by adapting existing CMOS manufacturing processes, allowing for the creation of multi-qubit processors with consistent performance characteristics across the chip, a critical step for scalable quantum computation.
Enhanced qubit coherence in silicon
Researchers have successfully engineered the silicon lattice to be isotopically pure (Silicon-28), drastically reducing magnetic noise. This has pushed the coherence times of spin qubits into the multi-second range, allowing for a significantly higher number of quantum operations to be performed before the quantum state decoheres.
High-fidelity two-qubit gates
The precision of two-qubit gates, the fundamental building blocks of quantum algorithms, has surpassed the 99.9% fidelity threshold in silicon. This level of accuracy is the minimum required for effective quantum error correction, marking a transition from noisy intermediate-scale quantum (NISQ) devices to fault-tolerance.
Cryo-CMOS for integrated control
Cryogenic CMOS (Cryo-CMOS) circuits are now being integrated directly on-chip or in the same package as the qubits. These specialised chips can operate at millikelvin temperatures, drastically reducing the number of wires needed to control the qubits and minimising thermal noise, which is a major source of errors.
Advanced 3D stacking and heterogeneous integration
We are seeing the first demonstrations of 3D-integrated quantum processors. This involves stacking layers of qubit arrays with layers of classical control and readout electronics, connected using through-silicon vias (TSVs). This approach allows for a massive increase in qubit density and functional integration.
On-chip quantum error correction (QEC) codes
Small-scale, hardware-efficient QEC codes are being implemented directly on semiconductor-based quantum chips. These codes can detect and correct certain types of quantum errors in real-time, extending the computational lifetime of the qubits and improving the reliability of quantum calculations.
Development of cryogenic memory
To support the Cryo-CMOS controllers, specialised cryogenic memory (Cryo-RAM) is being developed and integrated. This allows control signals and measurement results to be stored locally at low temperatures, reducing the latency associated with communicating with room-temperature electronics.
Photonic interconnects for chip-to-chip communication
The challenge of scaling beyond a single chip is being addressed with on-chip photonic interconnects. These convert quantum information from electrons (in spin qubits) to photons, allowing quantum states to be transferred between different quantum chips with low loss, a key technology for building larger, modular quantum computers.
Automated qubit calibration and tuning
As the number of qubits grows, manual calibration becomes impossible. AI and machine learning algorithms are now routinely used to automate the complex process of tuning and calibrating thousands of qubits, optimising their performance and keeping the quantum computer stable over long periods.
Monolithic integration of qubits and control logic
Beyond 3D stacking, researchers are achieving monolithic integration, where qubits and their control transistors are fabricated in the same silicon layer. This represents the ultimate level of integration, promising the most compact and efficient design for a quantum microprocessor, mirroring the architecture of a classical CPU.
Standardised quantum design kits
Semiconductor foundries are beginning to offer early-access process design kits (PDKs) for quantum components. These kits provide a standardised set of rules and models for designing silicon-based quantum circuits, enabling a broader range of designers to enter the field of quantum hardware development.
Improved materials for superconducting-semiconducting hybrids
There is significant progress in creating hybrid devices that combine the best of superconducting and semiconducting qubits. New material interfaces between superconductors and semiconductors are being developed to enable fast, high-fidelity control of semiconductor qubits using superconducting resonators.
What the future holds
With all the work going on in the field of quantum computing, the tech landscape will witness a major shift within the decade.
The emergence of fault-tolerant logical qubits
Within the next 5-10 years, the focus will shift from improving physical qubits to constructing the first ‘logical qubits’. A logical qubit is an abstraction formed from many entangled physical qubits, which are collectively used to encode and protect a single piece of quantum information from errors, enabling truly fault-tolerant quantum computation.
Distributed quantum computing via a ‘quantum internet’
The development of reliable quantum interconnects will lead to the first small-scale quantum networks. These networks will connect multiple quantum processors located in different labs or data centres, enabling distributed quantum algorithms and laying the groundwork for a future ‘quantum internet’ with applications in secure communication and sensing.
AI-driven discovery of quantum materials and architectures
AI will become an indispensable tool for designing the next generation of quantum hardware. Machine learning models will be used to sift through vast parameter spaces to discover novel materials with optimal properties for qubits and to design entirely new qubit architectures that are inherently more robust against noise.
‘Quantum-ready’ semiconductor foundries
Major semiconductor foundries will establish dedicated fabrication lines for quantum integrated circuits. This will commoditise the production of quantum chips, making powerful quantum hardware more accessible and affordable, and accelerating the pace of innovation across the entire quantum ecosystem.
The rise of topological qubits
While still in the research phase in 2025, the long-term goal is the realisation of topological qubits. These qubits encode information in the collective, global properties of a system, making them naturally immune to local sources of noise. If successful, topological quantum computing would offer a more direct path to fault tolerance, potentially leapfrogging other qubit modalities.
Qubits are the building blocks of quantum computers, and several competing technologies are currently in play. Superconducting circuits, which use tiny loops of superconducting material, are among the most prominent. Companies like IBM and Google have developed powerful processors using this approach. Trapped ions present another pathway, where individual atoms are suspended using electromagnetic fields and manipulated with lasers. This technique offers high fidelity and stability. Photonic qubits, which use particles of light, promise scalability and room-temperature operation, with firms like Xanadu and PsiQuantum championing this technology. Other notable approaches include spin qubits in semiconductors and topological qubits, each bringing unique strengths and challenges to the table.
One of the greatest challenges in quantum hardware is maintaining the delicate quantum states that enable computation. Quantum noise and decoherence—the process by which quantum information is lost to the environment—can quickly disrupt calculations. Researchers employ error correction techniques, advanced shielding, and refined control systems to preserve coherence. Innovations in materials science and circuit design have made strides, but the battle against noise remains an ongoing challenge. As quantum computers scale up, managing these effects becomes even more vital.
To keep quantum hardware stable, especially superconducting qubits, scientists often rely on cryogenics—ultra-cold environments that can reach temperatures close to absolute zero. Special refrigerators, known as dilution refrigerators, create these conditions, reducing thermal noise and allowing quantum effects to flourish. The design of quantum environments extends beyond cold temperatures, incorporating vacuum chambers and electromagnetic shielding to protect against outside disturbances. These specialised setups are crucial for reliable and repeatable quantum operations.
Building a practical quantum computer means going beyond a handful of qubits. Modular architecture, where several smaller quantum processors are linked together, represents a promising approach to scaling up. Integration with classical electronics, improved interconnects, and advances in quantum networking enable larger and more powerful systems. Researchers are also exploring error-tolerant designs and hybrid platforms that blend different qubit technologies for greater flexibility.
Companies and research labs at the forefront of quantum computing
The quantum hardware race is driven by a mix of established firms, ambitious startups, and world-class research institutions. IBM, Google, and Intel are among the giants developing superconducting and silicon-based quantum processors. IonQ and Honeywell lead the field in trapped ion technology, while Rigetti Computing pursues modular quantum architectures. European labs, including those at Delft University and the University of Oxford, have made significant contributions. In Asia, institutions like the Chinese Academy of Sciences and Japanese R&D centres are accelerating progress. Collaboration between academia, industry, and government is spurring innovation worldwide.
Looking ahead, quantum hardware is poised for rapid evolution. Researchers are investigating new materials, such as diamonds and graphene, for more robust qubits. Advances in miniaturisation, error correction, and quantum networking will help realise scalable and commercially viable quantum computers. The integration of artificial intelligence in quantum control systems, the rise of quantum cloud services, and the search for room-temperature qubits are shaping the next wave of breakthroughs.
Quantum hardware development: What lies ahead
The current era of Noisy Intermediate-Scale Quantum (NISQ) computing has proven that quantum processors can perform tasks beyond the reach of classical computers. However, the true promise of quantum computing—solving intractable problems in medicine, materials science, and finance—awaits the development of large-scale, fault-tolerant machines. The next 5 to 15 years will be defined by a critical transition, focusing on the key innovations required to bridge this gap.
The path to massive scalability
Scaling from hundreds of qubits to millions is the primary engineering challenge. The future lies not in simply building larger monolithic chips, but in rethinking the fundamental architecture of a quantum processor.
Modular architectures (chiplets): Inspired by modern classical CPUs, the future is modular. Quantum processors will be constructed from smaller, high-yield ‘quantum chiplets’ that are interconnected. This will allow manufacturers to select only the highest quality chiplets and combine them, dramatically improving the yield and cost-effectiveness of building a large-scale system.
Advanced 3D integration: To manage the immense complexity of wiring and control, quantum hardware will move into the third dimension. This involves stacking layers of qubit arrays on top of classical control and readout layers (heterogeneous integration), connected by vertical links. This approach drastically increases qubit density and reduces signal latency.
Architectural convergence: While different qubit modalities (superconducting, silicon spin, trapped ions) currently have distinct advantages, we will see a convergence of ideas. For example, the unparalleled manufacturing scalability of silicon will influence superconducting qubit design, while the high connectivity of trapped-ion systems will inspire new routing techniques in solid-state architectures.
The pursuit of qubit quality and coherence
A million poor-quality qubits are useless. The relentless pursuit of higher quality—longer coherence times and more precise operations—is paramount. The focus will shift from demonstrating basic functionality to achieving industrial-grade precision.
Materials science breakthroughs: The quality of a qubit is determined by its environment. Future progress will depend on breakthroughs in materials science, such as producing isotopically pure Silicon-28 to eliminate magnetic noise for spin qubits, and engineering ‘cleaner’ superconducting materials with fewer microscopic defects that cause decoherence.
Surpassing 99.99% gate fidelity: Achieving the ‘four nines’ of fidelity for two-qubit gates is a critical threshold for efficient quantum error correction. This will be achieved through a combination of AI-driven pulse shaping, which designs optimal electromagnetic pulses for gate operations, and designing qubits that are inherently less prone to errors and crosstalk.
Maintaining quality at scale: Ensuring that the millionth qubit is as good as the first is a monumental challenge. This requires developing fabrication processes with unprecedented uniformity and creating new techniques for shielding large arrays of qubits from correlated noise that can affect the entire processor at once.
The dawn of practical fault-tolerance
Fault-tolerance is the paradigm shift that will unlock quantum computing’s full potential. This involves moving from fragile physical qubits to robust, error-corrected ‘logical qubits’.
Hardware-efficient QEC codes: Early error-correction codes, like the surface code, require thousands of physical qubits to create one logical qubit. The future lies in developing more efficient codes that drastically reduce this overhead. This will make fault-tolerance achievable with far fewer qubits, bringing the timeline for a useful logical processor forward significantly.
Real-time decoding and feedback: Quantum error correction is not a post-processing step; it must happen in real-time. This requires a dedicated classical co-processor, likely operating at cryogenic temperatures, that can detect an error, diagnose its cause, and apply a correction faster than the quantum state decoheres—a feedback loop operating on nanosecond timescales.
The first logical qubits: Within the next 5-10 years we will see the first demonstrations of logical qubits that have a longer lifetime and perform more accurate operations than any of their constituent physical qubits. This will be the ‘Wright brothers moment’ for fault-tolerant quantum computing, proving that building a stable quantum memory is possible.
Interconnectivity and the quantum internet
To scale beyond the limits of a single cryogenic refrigerator, quantum computers must learn to talk to each other. This requires the development of ‘quantum interconnects’ to network processors together.
Quantum transduction: The most promising approach for long-distance links is quantum transduction, which involves converting the quantum state from a qubit (microwave-frequency) to a photon (optical-frequency). These photons can then be sent over standard fibre-optic cables, enabling the creation of powerful, distributed quantum computing clusters.
Distributed quantum computing: Interconnects will allow a single, massive quantum algorithm to be distributed across multiple, smaller quantum processors. This not only provides a path to scaling but also adds a layer of redundancy and flexibility to the overall computational system.
Foundations of the quantum internet: These same interconnect technologies form the hardware backbone of a future quantum internet. This network would enable fundamentally secure communication, enhanced sensing capabilities, and access to remote quantum computers from anywhere in the world.
Deep integration of classical and quantum control
A quantum computer is a hybrid system, and the boundary between the classical and quantum worlds will become increasingly blurred. The future is a deeply integrated system-on-a-chip.
Cryogenic CMOS (Cryo-CMOS): The jungle of wires connecting a quantum chip to its room-temperature control electronics is a major bottleneck. The definitive trend is to build specialised Cryo-CMOS control chips that operate at cryogenic temperatures, sitting right next to the quantum processor. This reduces latency, noise, and heat load, and is essential for controlling millions of qubits.
AI-driven autonomous operation: It is impossible to manually tune and calibrate a million-qubit processor. The quantum computers of the future will be self-driving, using sophisticated AI and machine learning algorithms to continuously monitor performance, diagnose errors, and autonomously re-calibrate the system on-the-fly.
The Quantum System-on-a-Chip (QSoC): The ultimate endgame of this integration is the QSoC. This will be a single, packaged device containing the quantum processor, the Cryo-CMOS control and readout circuitry, and perhaps even the real-time error correction decoders, mirroring the architecture of a modern classical microprocessor.
Exploring novel and exotic qubit architectures
While a few qubit modalities currently lead the pack, the search for a ‘perfect qubit’ continues. Long-term research into novel architectures could leapfrog current approaches.
The promise of topological qubits: The holy grail of quantum computing is the topological qubit, which stores information in the very ‘shape’ of its quantum state, making it naturally immune to local sources of noise. While scientifically challenging, a breakthrough here would offer a direct path to fault-tolerance without the massive overhead of current QEC codes.
Neutral atom arrays: This modality has seen explosive growth. Using lasers to trap and manipulate hundreds or even thousands of individual atoms, these systems offer high qubit numbers and flexible connectivity. Future developments will focus on improving gate speeds and fidelities to make them competitive for complex algorithms.
As quantum hardware evolves from silicon to superconductors and beyond, new qubit technologies, innovative environments, and bold scaling strategies are defining the landscape. With leading companies and labs pushing the boundaries, and with future trends promising even greater advances, the quantum hardware race is set to deliver profound changes for science and society.
