IVAN NIKITSKI, EUROPEAN PHOTONICS INDUSTRY CONSORTIUM (EPIC)
Quantum is still in its early days, but the technology has been heating up. During the last five years, companies such as Google, IBM, Honeywell, and Microsoft have developed quantum computers, and some now offer cloud quantum computing services. In 2021, the European Union (EU) launched the HPCQS project, which is aiming to integrate two quantum simulators — each capable of controlling more than 100 qubits — with two existing European Tier 0 supercomputers, located in France and Germany, by the end of 2025. Here, the broader objective was to provide noncommercial cloud access to public and private European users to solve complex challenges in areas such as materials and drug design, logistics, and transportation.
Market forecasts reflect such an uptick in activity: The global quantum computing market is projected to grow from $1.2 billion in 2024 to $12.6 billion by 2032, at a compound annual growth rate of 34.8%, according to Fortune Business Insights. During this period, the highest market share (by end user) is predicted to be health care. This is due to the increase in the use of quantum-enhanced machine learning methods and the creation of virtual environments in which specialists
can examine variables, such as skin temperature, electrolytes, and circulation, on digital human replicas.
Next is the banking, financial services, and insurance sector. This owes to the increased use of computing services to resolve complex financial calculations faster as well as the need to address the security challenges posed by quantum computers. In terms of market share, automotive, energy and utilities, chemical, manufacturing, transportation, and logistics follow the health care sector and the banking, financial services, and insurance sectors.
Yet, the systems that comprise this iteration of quantum computers that some of industry’s largest and most influential companies have introduced remain in the prototype stage. Currently, developers are focused on resolving bottlenecks related to scaling the required number of physical qubits and decreasing error rates and noise, among other challenges. This technology is also expensive, with costs particularly high for platforms that require intricate cooling technologies on top of the cost to develop and operate. There is also a well-documented skills gap.
For these reasons, global consulting firm McKinsey & Company has estimated that only 5000 quantum computers will be operational by 2030. The agency’s forecast said that the hardware and software necessary for managing the most complex problems will not be available until 2035 or later.
Photonic quantum computers
The fundamental unit of information in quantum computing is the qubit. Unlike classical bits, which can be either 0 or 1, qubits can exist in a superposition of states, meaning they can simultaneously represent both 0 and 1 to varying degrees. This property enables quantum computers to process vast amounts of information more efficiently and far more rapidly than classical computers for certain tasks.
A variety of technologies can be used to make qubits. These include trapped ions, photons, artificial atoms (which can be real and/or artificial), and spin qubits. Superconducting materials, such as aluminium, can also make qubits. Each fabrication approach offers advantages and disadvantages based on physical properties, scalability, and practical implementation.
Photonic quantum computers use several critical elements for their operation. Cluster states, using either single photons from quantum dots, integrated photon-pair sources, or squeezed light are among the most crucial. Fast and low-loss feedforward, which can adapt to measurements settings in between the arrival of bunches of photons, is another essential component for pumping the sources, as are integrated lasers. Efficient photon detection is enabled by single-photon detectors. Waveguides, beamsplitters, phase shifters, and optical switches facilitate the necessary photon guidance, interference, modulation, and routing in quantum circuits. Quantum memory elements, such as color centers and optical delay lines, provide storage and synchronization. Additionally, error correction, feedforward circuits, and real-time error correction codes are necessary to maintain quantum coherence and to counteract noise that is created due to photon loss.
Between 2019 and 2024, the highest investment in quantum technology platforms was in photonics ($1.2 billion), according to Yole Group’s Quantum Technologies 2024 report (Figure 1). This is due to the platform’s stability, ambient temperature operation, and market availability of photon sources and detectors. Another key driver for this investment is that photons are already used in telecommunications and data communications applications, and therefore, photonics offers a mature platform for interconnecting many photonic quantum computers. Plus, photonics enables hybrid approaches that combine the strengths of different quantum technologies. Photons effectively interact with other qubit system types, such as trapped ions or superconducting qubits.
Figure 1. The different architectures of quantum computers, their applications, and requirements. DMD: digital mirror device; Q: quantum.
The next biggest area of investment is superconducting, at $1.1 billion over the same timeframe. Superconduction is the most mature technological approach, and its primary advantage is fast gate operations. At the same time, it requires extremely low temperatures in the millikelvin range, which is energy-intensive and costly. Trapped ion, neutral atom, and silicon qubit approaches followed in Yole’s investment rankings. Neutral atom and silicon qubit approaches both benefit from a scalability advantage through the use of wafer-scale technologies and existing industrial foundry infrastructure.
Technology advancements in Europe
In 2018, as part of a move toward quantum European sovereignty and better production facilities, the EU launched its Quantum Technologies Flagship. The launch aimed to provide €1 billion to support numerous projects in quantum technology and to thereby consolidate and expand European scientific leadership and excellence in quantum technologies. The response has been swift, and European companies are meeting this challenge in the realm of photonic quantum computing.
QuiX Quantum, founded in the Netherlands in 2019, is one of Europe’s leading quantum computing companies based on integrated photonics technology (Figure 2). The company is developing a scalable and energy-efficient universal quantum computer for health care, AI, logistics, high tech, and finance applications. QuiX is under contract to deliver prototype 8-qubit and 64-qubit versions to the German Aerospace Center (DLR) by 2027.
Figure 2. QuiX Quantum’s universal quantum computer, using photonic technology. The system supports health care, AI, logistics, high-tech, and finance applications. Courtesy of QuiX Quantum.
The core elements of QuiX’s platform include its quantum light sources and universal quantum processors. In combination, these elements generate n-dimensional entangled states, i.e., cluster states, and a fast feedforward mechanism for adapting the measurement settings in between clock cycles. QuiX’s quantum computers are modular, which means they contain many fiber interconnects. The company’s use of silicon nitride waveguides ensures low coupling losses. The underlying physics here is the refractive index of the optical fiber and waveguide, which are matched, as is the diameter of the mode field.
QuiX has also developed a special-purpose quantum computer to solve specific problems in the optimization and simulation field. The company launched this computer in September 2024 as the Bia quantum cloud computing service. The 20-optical channel Bia system comprises a light-generation module, a quantum processing unit, a light detection module, and advanced quantum control software. Bia technology can be combined with off-the-shelf components, and the complete package is designed for seamless integration with traditional computing infrastructure, representing a pivotal movement toward hybrid computation. The processing unit, called Alquor, is a low-loss, multichannel, reconfigurable interferometer, which allows the user to perform arbitrary, controlled linear optical unitary transformations between several optical channels. The processor therefore provides a solution for applications in quantum communication, quantum random number generation, and machine learning.
VTT Technical Research Centre of Finland Ltd. is another organization that has achieved milestone strides in quantum computing. In collaboration with IQM Quantum Computers, VTT developed Finland’s second quantum computer, a 20-qubit system, in work that builds on a 5-qubit quantum computer — and that now includes an ambitious road map to scale to a 50-qubit system. The center’s vision includes creating quantum systems with up to 300 qubits to achieve quantum advantage, enabling practical and transformative applications. VTT additionally works as part of Qu-Pilot, an EU-funded project to develop and provide access to the first pilot production facilities for quantum technologies in Europe. Qu-Pilot runs in parallel to the Qu-Test initiative to provide an infrastructure for testing and experimentation with quantum technologies.
VTT’s thick silicon-on-insulator (SOI) platform in 3 µm provides the possibilities for both hybrid and monolithic integration of active and passive components. The dimension of the current waveguide provides effective mode confinement and is equipped to handle issues arising from wall roughness, enabling the SOI platform to benefit from ultralow-loss properties.
Other capabilities from VTT include cryo-compatible, low-loss optical optoelectronic packaging, 3D integration, and photonic integrated circuits (PICs) assembly (Figure 3). The organization is working on devices, such as germanium avalanche photodiodes and germanium PIN photodiode receivers, for quantum key distribution applications. It is also developing superconducting nanowire single-photon detectors, also primarily for quantum key distribution applications.
Figure 3. Key building blocks of VTT Technical Research Centre of Finland Ltd.’s integrated photonics platform.
At the same time, VTT is developing a low-loss silicon nitride platform for quantum sensing and communication applications. This platform is comprised of active and passive devices that cover a wavelength range between 900 and 1550 nm. The platform offers active components such as graphene photodetectors and modulators. VTT previously developed wafer-scale graphene-based photodetectors with high responsivity in this way.
VTT’s work in integrated photonics highlights the importance of the sustained development of PICs, which function as a core computation unit on which photonic quantum computers rely. In these architectures, the PIC is connected to several optical fibers — though current expectations are that the numbers of optical fibers in these systems will exceed 100 by 2030. The performance of such a quantum computing system can be compromised by optical path losses; saving even 1% in the fiber-to-chip connection is critical.
Clearly, one of the main challenges in realizing photonic quantum computers is the implementation of a highly efficient optical system, which requires exceptionally low optical loss performance to properly achieve quantum supremacy. A percentage of the optical power of the system is lost in the optical interfaces connecting these architectural blocks of a quantum computer, and the insufficient fiber array accuracy currently available in the market is unable to overcome this bottleneck.
Founded in 2021, Eindhoven, Netherlands-based MicroAlign has developed an approach to enable precision alignment of fiber arrays. The company is maximizing the reach and efficacy of newly developed technology based on high-complexity photonic chips. MicroAlign’s solution is a high-accuracy fiber array, for which all fibers are assembled via an active alignment method to provide a core pitch accuracy of <100 nm, which can be scaled to tens of fibers in an array. These fiber arrays could be fundamental for the manufacturers of quantum photonic computers endeavoring to accelerate the development and adoption of the technology into new markets.
Finally, TOPTICA Photonics AG is also driving gains as a developer and manufacturer of lasers for quantum computing and quantum communications as well as quantum sensing. In support of quantum computing, the company provides a range of laser solutions for ion, neutral atom, and nitrogen-vacancy center qubit systems. TOPTICA’s laser offerings include highly coherent tunable diode laser systems, both amplified and nonamplified; high-power amplifiers; stable frequency reference systems including wavelength meters, spectroscopy cells, and frequency combs; complete laser system solutions, optionally fiber-coupled; and 19-in. rack-mounted lasers for wavelengths ranging from 330 to 1770 nm. These systems are highly modular, fully integrated, and frequency stabilized to enable customers in the quantum realm to mix and match different laser types.
Future outlook
Quantum computing holds immense potential but faces critical challenges on the path to large-scale implementation. Scalability is a major hurdle, with current devices housing only tens to hundreds of qubits — far from the thousands or millions needed for practical use. Environmental noise and decoherence threaten qubit stability, and high error rates in quantum gates demand breakthroughs in error correction. Optimized quantum algorithms for real-world problems are scarce, and existing quantum programming tools remain underdeveloped compared with classical software. Lastly, a skills gap in quantum expertise highlights the need for robust training programs to prepare future researchers and engineers. This skills gap is evident in the need to put these critical algorithms toward application and the need for improved hardware and components that can support systems developed at scale.
Looking toward 2035, Paris-based Institut d’Optique has made several recommendations for addressing the current limitations of quantum computing technologies within Europe. Technical issues identified by the institute include those involving lasers, which will need more power, greater wavelength range, lower noise, and a higher technology readiness level, and at a lower cost, with a reduction in user interaction. There is also a need for more efficient single-photon sources with improved miniaturization. More advanced optical detectors are also required, according to the institute, along with better cryogenic compatibility, lower loss reduction, and greater modulation for sources and detectors.
Fortunately, supply issues in these areas are not currently expected in Europe. This is a testament to its development and supply of high-quality laser sources and photonics systems for quantum technology. Europe serves as much as 80% of the current global market for quantum needs, according to estimates.
However, greater EU sovereignty for photonics components, improved high-end foundry fabrication, and more assembly lines for PICs are necessary growth steps. In addition, moving from small volume with high cost to larger volumes with low cost necessitates a stable, long-term market with greater capital investment from governments and European contracts. As R&D efforts continue in these areas, integrated photonics will drive innovations to redefine quantum computing, heralding an era of technology that will reshape industries and society.