The Inevitable Opportunity For Photonics In Quantum Computing
Author: Dr Tess Skyrme, Principal Technology Analyst at IDTechEx
Quantum computers can be built in many ways. You may be familiar with the competing modalities claiming to offer various advantages over others in terms of quality, scalability, cost, and more. However, it is increasingly apparent across them all that new generations of optics and photonics technologies will be essential. This opens an exciting supply chain opportunity for many players, old and new, in the photonics eco-system. It creates a chance to claim future market share of what IDTechEx forecasts to be a quantum computing hardware market worth over $US10B by 2045 in their latest report, “Quantum Computing Market 2025-2045: Technology, Trends, Players, Forecasts”.
The main categories of quantum computing hardware modality are superconducting, trapped-ion, neutral atom, photonic, silicon-spin, diamond and topological. Whilst their specific designs can be incredibly different, much of the fundamental blueprint remains the same. Moreover, optics and photonics play a role within multiple core functions in various hardware approaches. This includes readout, cooling and control, modular connectivity and data center integration.
Blueprint for a Quantum Computer: Qubits, Initialization, Readout, Manipulation. Source: IDTechEx
Photon detectors and imaging for readout systems
Many methods of reading out the solution of a problem solved with a quantum computer use photon detectors or imaging.
Ironically, within photonic quantum computing itself there is often a need for such highly sensitive single photon detection that superconducting nanowires are utilized to achieve this. As a result, ongoing efforts are to integrate superconducting nanowire single photon detectors (SNSPDs) into photonic integrated circuits (PICs). Indeed, one of the leaders in photonic quantum computing PsiQuantum have disclosed that their roadmaps include research into higher temperatures SNSPDs based on manufacturable metals. Ultimately this represents a wider opportunity for more accurate single photon detectors for photonics quantum computing read-out purposes which reduces the compromise on cooling power and space this sub-sector is currently facing. Such innovations could prove crucial in unlocking the value proposition of the large-scale fault-tolerant photonic quantum computing sub-sector, for whom their ‘hot qubits’ seek to offer a reduced infrastructure complexity to its superconducting competitors.
On the other hand, the simplicity of using established imaging and microscopy methods for readout is a flag-ship advantage of modalities such as diamond, neutral atom and trapped-ion platforms. For example, Hamamatsu have a range of photo-multiplier tubes (PMTs) and electron multiplying charged couple devices (EM-CCDs) commercially available off-the-shelf for the trapped-ion and neutral atom communities respectively. Meanwhile, the diamond platform pursued by players like Quantum Brilliance XeedQ could use even simpler complementary metal oxide-semiconductor (CMOS) cameras. The ability of these modalities to use established imaging methods for readout could once again prove essential in offering an advantage in scalability over competitors. Especially since, for some other modalities, the ‘wiring challenge’ associated with readout scales with qubit number, whilst imaging an entire qubit array at once is much more efficient.
Laser control and cooling
Did you know that lasers also pose an alternative to cryogenics for cooling qubits? Whilst for many the imagery behind lasers is high-power beams which may be associated with heat, ignition, cutting or communications, in the world of quantum computing they are better known for their ability to take atoms down to very low energy states.
Laser cooling approaches vary between quantum computing approaches and company preferences, but ultimately trap or tweezer atoms or ions using multiple lasers firing equally in opposing directions. One of the major advantages of this approach is that this can be achieved using established components and be operable at room temperature. Overall, laser cooling is considered much more power, cost and resource efficient than the cryo-stats needed for supercomputing quantum computing.
Lasers within quantum computers are also sources of qubit control and manipulation, as for cooling. In this regard however, there are some signs within the industry that the efficiency of electrical and digital control could be superior when it comes to system fidelities (low errors) and scalability. One example of this comes from UK-based Oxford Ionics, who have pioneered an electronic based qubit control method for use within a trapped-ion system. This strategy, alongside others advocating for digital readout such as SEEQC, perhaps reinforces that whilst in many case the use of photonics and optics is offering an advantage, the desire to get as much of a quantum computers components as possible into packages manufacturable within existing semiconductor foundries also remains.
Modular connections and data center integration
As quantum computer developers continue to set their sights on scalability, calls to make repeatable modular systems which can be connected together have intensified. The drivers for this approach are multi-faceted. To a degree it echoes how success in scalability has been achieved with classical computing, and there is also some evidence it is in line with cutting edge approaches in error correction.
The challenge with the modular approach however is that creating successful connections between systems is non-trivial. Entanglement is hard enough to maintain in neighboring qubits on a single chips, never mind between arrays of them distributed between multiple systems (whether it be racks or cryo-stats).
Once again however, photonics is offering an answer. NuQuantum have developed a quantum networking unit (QNU) which uses photonics to distribute entanglement across multiple processors. They also recently announced a quantum photonic interface (QPI), a technology which ultimately creates an interface between matter and light, qubits and photons. Prototype versions of this QPU have already been integrated and tested within Infleqtion’s trapped atom vacuum system.
Market outlook
Overall, beyond the competition between companies and qubit modalities – or focus on the contest to win the quantum race – is an underlying opportunity across the board for optics and photonics. This includes the readout, cooling, control, and connectivity needs present in almost all approaches being pursued today.
Even beyond the designs of individual companies’ quantum computers though, is the fundamental need for quantum computers to become integrated within existing networks of data centers, classical computers, and communications networks. Photons are already the globe’s medium of choice when it comes to data, and for commercial success quantum computers can not avoid the need for photonics of some form.
IDTechEx’s report, “Quantum Computing Market 2025-2045: Technology, Trends, Players, Forecasts”, covers the hardware that promises a revolutionary approach to solving the world’s unmet challenges. The quantum computing market is pitched as enabling exponentially faster drug discovery, battery chemistry development, multi-variable logistics, vehicle autonomy, accurate asset pricing, and much more. Drawing on extensive primary and secondary research, including interviews with companies and attendance at multiple conferences, this report provides an in-depth evaluation of the competing quantum computing technologies: superconducting, silicon-spin, photonic, trapped-ion, neutral-atom, topological, diamond-defect and annealing. IDTechEx also presents independent scores for ‘quantum commercial readiness level’ to assess how the quantum computing industry is progressing compared to the evolution of the classical computing industry that came before it. The total addressable market for quantum computer use is converted to hardware sales over time, accounting for advancing capabilities and the cloud access business model. The quantum computing market is forecast to surpass US$10B by 2045 with a CAGR of 30%.
To find out more about the IDTechEx report “Quantum Computing Market 2025-2045: Technology, Trends, Players, Forecasts”, including downloadable sample pages, please visit www.IDTechEx.com/QuantumComputing.
For the full portfolio of quantum technology market research from IDTechEx, please visit www.IDTechEx.com/Research/Quantum.
