Grounded in the principles of quantum mechanics — superposition, entanglement, and interference — quantum computing is one of the most intriguing technologies of our time. It is also deeply misunderstood; the term “quantum” is often misused in popular culture to imply futuristic speed or capability. Courtesy of iStock.com/PhonlamaiPhoto. While there is no doubt that quantum computing promises a transformative scientific leap that lacks a perfect analog, it is, at its core, a tangible, physical technology. This is true in the sectors in which quantum computing promises to yield breakthroughs, including materials, energy, finance, cryptography, and machine learning. Just as laser creator Theodore Maiman questioned the practical value of the first laser in 1960, quantum computing today stands at a similar turning point as it matures from a physics experiment into a practical technology. Broadly, quantum computing is an intimidating field. Even in the sophisticated realm of computing, the ability to perform computations using quantum phenomena underscores a legitimately new paradigm. Optics technologies and components are central to viable, practical quantum computing. The same field and set of principles that govern lasers, interferometers, and photonics also enable the precise control of quantum states. Courtesy of Classiq. Yet while the principles underpinning this technology are quantum, the technologies that are foundational to quantum computing are familiar. Optics — the same field and set of principles that governs lasers, interferometers, and photonics — enables the precise control of quantum states. In addition to its essential role in harnessing quantum phenomena and enabling the manipulation of quantum states at the smallest scales, optics is also central to the hardware and control systems of quantum computers. Lasers, waveguides, and optical fibers provide the precision and scalability needed to manipulate qubits — and, as a result, quantum information. Current quantum computing systems will not replace classical computations anytime soon. Today’s quantum processors have limited, noisy qubits and rely on early-stage error correction. Although academic research and, more recently, industry sectors have made significant progress, quantum systems have not yet outperformed classical systems in real-world problems — a point known as “quantum utility.” Moreover, the current hurdles to quantum utility are profound. Fidelity, scalability, and connectivity each represent complex bottlenecks. Together, these obstacles form a formidable barrier to widespread adoption. The solution exists in the same optical methodologies that underpin many existing quantum computing schemes. In quantum computing, optics drives information flow, enables precise control, and sustains the connections that allow entire systems to function as one. It therefore paves the way to practical quantum computing. Fidelity, scalability, and connectivity Despite rapid advancements, quantum computing has yet to deliver widespread impact. This is not because the underlying science is unproven. Rather, it is because the hardware remains difficult to build and control. Achieving useful quantum computing requires resolving engineering challenges related to fidelity, scalability, and connectivity, all of which are tightly constrained by the realities of working with quantum systems. Fortunately, many of these challenges are being addressed using well-established optical tools rather than hypothetical technologies. Fidelity refers to how accurately quantum operations can be performed without introducing errors. Qubits are inherently fragile; even minor sources of noise, timing mismatches, or environmental interference can disrupt them. As a result, executing reliable computations demands exceptional precision at every step, from gate operations to measurement. Optical control systems — including stabilized laser pulses, clean beam delivery, and carefully shaped waveforms — play a critical role in reaching the levels of precision required to keep error rates low and quantum states coherent. Scientists have demonstrated gate fidelities >99.9%, but maintaining this level across thousands of operations in a sequence remains elusive. Additionally, for current quantum photonic system architectures, advanced fabrication techniques are needed to reduce the overall footprint while maintaining the coherence and fidelity of quantum operations that are critical for developing large-scale quantum processors. Scaling introduces architectural complexity: Growing qubit arrays must remain stable, synchronized, and readable without adding noise or heat, both of which can disrupt the operation. Optical systems, particularly those using integrated photonics, offer a promising path. These systems support high-bandwidth, low-crosstalk control while preserving precision as systems grow. As it relates to quantum networks, the global connectivity of quantum systems will increasingly depend on photonics technologies. Future advancements are expected to extend communication range, integrate quantum memory, and pursue entanglement on a global scale. Each of these pursuits ties directly to a need for scalability, and each presents its own challenges. As systems scale, connectivity becomes critical to functionality. Future quantum computers will move beyond single processors toward modular systems and distributed networks, because transmitting quantum states is impossible over copper wires. Photons, on the other hand, excel at carrying quantum information over distances because they resist decoherence while moving at light speed. Photonic links enable entanglement distribution, remote operations, and network architectures that classical connections simply cannot support. They also hold the key to efficient data transfer between quantum processors and classical computing resources. Quantum technology’s lifeblood There are many ways to create and control qubits, with each giving rise to different quantum computing paradigms. For example, superconducting quantum computers — such as those developed by IBM — rely on coils cooled to near absolute zero to initiate a superconducting state. Trapped-ion quantum computers — including those from IonQ — use electromagnetic fields to form potential energy wells that confine charged particles. Fundamentally, optics permeates every layer of the quantum stack. Regardless of the qubit paradigm used, optics and photonics technologies are integrated into nearly every aspect of the hardware. At the chip level, optics creates environments where qubits reside, from optical traps to photonic waveguides. Further, in the control layer, lasers and modulators perform precise operations with spatial and temporal accuracy. For measurement, optical systems illuminate qubits with state-selective light and collect the resulting signals. And in communication, photons carry quantum information across chips and devices. Optical systems and components operate at every layer of the quantum stack, including the control layer. Lasers and modulators perform precise operations with spatial and temporal accuracy. Courtesy of iStock.com/MikeShots. Trapped-ion quantum computing systems hold ions with electromagnetic fields. Laser cooling reduces particle motion to near zero, creating the stable environment essential for accurate operations. Courtesy of Stock.com/koto_feja. In photonic quantum systems, light is not just a tool — it is the qubit itself. Quantum information lives in photon properties, such as polarization and phase. These platforms offer natural mobility and long coherence times, but they require exceptional precision — guaranteed only by identical photons, lossless routing, and efficient single-photon detection. Precision matters most Quantum computing must make strides toward reliability before it can achieve utility. Unlike classical bits, which are largely stable in noise, qubits are fragile and vulnerable to thermal shifts, electromagnetic interference, and timing errors. Without quantum fidelity as the foundation, nothing higher on the value chain can stand. This foundation has three main components: gate fidelity, readout fidelity, and state preparation — or, in other words, operation accuracy, measurement reliability, and initialization consistency. When algorithms require thousands of operations, even tiny error rates compound into unusable results. Optical systems deliver this needed precision across various quantum platforms. The exact way that optics enables quantum computing differs by system type. Neutral atom systems, such as those developed by QuEra, build entire processors from light. These systems leverage highly focused laser beams, commonly implemented as optical tweezers, to trap individual atoms with exceptional precision. The gradient force arising from the spatial intensity variation of the laser beam creates potential wells that capture and hold atoms at the focal point. These traps not only facilitate the formation of defect-free qubit arrays, they also enable the dynamic rearrangement of atoms for error-correction and scaling. Additionally, optical lattices — formed by the interference of multiple laser beams — create periodic grid-like potentials that are ideal for implementing quantum gates with high spatial control. Even state readout happens optically in neutral atom systems: Upon laser light illumination, ions emit state-dependent fluorescence, which is captured by high-precision photodetectors to determine their quantum state with submicron precision. In addition to fluorescence detection, another approach is direct photonic detection, where single-photon detectors measure the presence or absence of photons that represent qubit states. Advanced techniques, such as the use of “magic-wavelength” tweezers, further enhance readout fidelity by optimizing light-matter interactions and minimizing disturbances during measurement. Optical control in neutral atom systems extends beyond trapping to actively driving qubit operations. Laser pulses induce coherent transitions between atomic states, often through stimulated Raman transitions to excite atoms to Rydberg states. Rydberg excitation produces strong, controllable interactions between atoms, and these interactions are essential for implementing two-qubit entangling gates. This level of optical control is a key advantage in constructing scalable, high-fidelity quantum processors. Meanwhile, trapped-ion systems hold ions with electromagnetic fields, and computation depends entirely on laser control. Laser cooling reduces particle motion to near zero, creating the stable environment essential for accurate operations. Ion cooling is performed via techniques such as Doppler and/or resolve sideband cooling, which minimizes motional excitations and enhances coherence. For gate operations, precisely shaped laser pulses drive quantum state changes through Raman transitions and other techniques that rely on laser-induced forces to entangle ions by coupling their internal states with collective motional modes. This set of approaches provides the fine control needed to manipulate individual qubits within dense arrays while minimizing crosstalk between neighboring qubits. Even superconducting and bosonic platforms, which operate in the microwave domain, increasingly integrate optics for better communication. Microwave-to-optical conversion via devices such as electro-optic modulators and piezoelectric resonators converts microwave qubit signals into optical frequencies. This conversion is essential for transmitting quantum information over long distances using optical fiber. Also, lasers and optical timing systems provide the precise clocking and synchronization necessary for coordinating complex operations across superconducting circuits. Integrated photonics and full systems Photonic quantum systems require photons to be virtually identical in frequency, polarization, phase, and timing. Creating this uniformity demands sophisticated optical engineering throughout the system, from light sources to beam paths to detectors. Real-time feedback loops maintain quantum performance during operation. Optical sensors continuously monitor system states, triggering immediate corrections when errors appear. These rapid interventions prevent small issues from cascading into system-wide failures. The connection between optics and quantum fidelity is fundamental. High-precision optical systems are not just complementary to quantum computing —they are essential to its function. Therefore, as practical quantum advantage becomes attainable, investments in optical precision will define which platforms succeed. Necessary quantum computing hardware remains difficult to build and control, despite considerable progress. Achieving useful quantum computing requires resolving engineering challenges, primarily those related to fidelity, scalability, and connectivity. Courtesy of iStock.com/Bartlomiej Wroblewski. Photonic integrated circuits (PICs) enable the stabilization of single-photon logic operations. More specifically, they enable the integration of optical components such as beamsplitters, waveguides, and modulators onto a single chip. The placement of an active element, such as a phase modulator on a chip, for example, to dynamically control photon paths, can also streamline the implementation of quantum error-correcting protocols. Beamsplitters and interferometers split, combine, and/or interfere with photon paths, enabling the implementation of quantum gates that are analogous to those in other quantum architectures. Beyond integrated components and the compact, high-performance architectures that they enable, PICs in quantum systems enable lower losses. Advanced materials and fabrication techniques minimize energy losses, preserving the high fidelity required for quantum operations. On-chip multiplexing is also possible. The capacity to simultaneously manipulate multiple qubits is an essential requirement for scaling quantum systems. Certain process advantages must be considered: Photon-based quantum computing benefits from the precisely controlled light-matter interactions, and nonlinear optical processes, such as parametric down-conversion, enable the generation of entangled photon pairs. Heralded photon sources ensure the reliable production of single photons on demand. These techniques facilitate robust qubit initialization, manipulation, and measurement. Importantly, these benefits extend to the very constraints that continue to hinder quantum computing. Integrated photonic chips will be central to scaling quantum systems. Future designs are expected to increase qubit density by incorporating multiple layers of waveguides to enable 3D photonic architectures. This will dramatically boost the number of qubits manipulable on a single chip. These chips will also open pathways to use advanced precision fabrication methods, such as subwavelength patterning, to minimize optical losses and improve component efficiency. Finally, they will trigger a necessary shift toward hybrid integration. A seamless interface between photonic chips and other quantum platforms, including superconducting and trapped-ion systems, will ensure that complete systems can leverage the strengths of diverse and complementary quantum technologies. Into the domain of compute Opportunities for quantum computing to progress exist alongside more established high-performance computing (HPC) architectures. Overlaying quantum computing’s strengths with those of HPC to build out hybrid quantum-classical systems offers several promising paths forward. High-bandwidth optical interconnects could facilitate efficient data transfer between quantum processors and classical computing resources. Developing co-designed algorithms that optimize resource use across quantum and classical platforms would leverage optical components to bridge the gap. And engineering data buses capable of handling both classical and quantum information simultaneously would enhance complete-system versatility. There is an inherent and complementary benefit to aligning the growing science of quantum computing with HPC systems. The solutions from industry players pushing the boundaries of integrated photonics in quantum computing complement earlier innovations in silicon photonics — such as integrated modulators and beamsplitters, as well as advanced fabrication techniques. For example, the French firm Alice & Bob is developing solutions that integrate micro-ring resonators, Mach-Zehnder interferometers, and high-speed phase modulators on a single chip. This approach minimizes optical losses, enhances stability, and enables robust on-chip quantum interference and entanglement. These represent key steps toward scalable photonic quantum processors. Elsewhere, quantum optical computing companies such as Xanadu and PsiQuantum are applying quantum simulation and optimization techniques to the design of integrated photonic chips. By accurately modeling light propagation within complex circuit architectures, these companies have developed approaches that improve fabrication processes, reduce losses, and enhance overall device performance. These factors are vital for advancing both quantum and classical optical applications. Quantum compute and optics: The future The synergy between optics and quantum computing is set to mount as emerging technologies drive next-generation systems. Several key trends, in addition to integrated photonic chips and the co-integration of HPC/quantum architectures, are poised to shape the field. For example, robust error-correction methods — imperative for reliable quantum computation and optical approaches — are anticipated to play a pivotal role in future schemes. Efficient encoding through the use of photonic qubits encoded in higher-dimensional spaces can be used to represent logical qubits more compactly, reducing redundancy in error-correction protocols. Plus, deploying advanced optical feedback systems for rapid error detection and correction will help to maintain computational stability even as systems scale. Also, the global connectivity of quantum systems will increasingly depend on photonics technologies. One anticipated advancement targets extending the communication range of secure quantum communication using quantum repeaters based on entangled photon pairs. The integration of quantum memory into photonic networks will allow for effective storage and synchronization of quantum states. The pursuit of global-scale entanglement holds tremendous opportunity for free-space optics to distribute entanglement across vast distances. These are not just isolated research advancements. They represent infrastructure under development for a quantum future. Like the fiber optic networks that evolved to support global telecommunications, optical technologies create the foundation for quantum systems to scale beyond research. Just as photonics transformed the laser from a laboratory novelty to the backbone of modern technology, it is now laying the foundation for quantum computing’s leap into real-world utility. This shift from scientific curiosity to core technology does not happen overnight. It requires infrastructure, standards, and precision. In quantum computing, that foundation is built with light. Meet the author Erik Garcell, Ph.D., is director of quantum enterprise development, North America, at Classiq Technologies, a developer of quantum software. He previously served as innovation product manager at IP.com and as an innovation research scientist at Kodak Alaris; email: erik@classiq.io.