GoKawiilThis article is part of a series documenting quantum computing technologies and their ecosystem – the differing approaches, the key players behind them, and the key technologies that are driving us towards a quantum future. Part one looked at superconducting qubits (materialized in key industry giants such as IBM and Google) and trapped ion qubits (through IonQ and Quantinuum).
In this second part, we’ll be looking at quantum photonics – a light-based technique of defining the quantum unit of computation, the qubit. We’ll take a brief look at the what and the why of quantum photonics, and then materialize it by focusing on two particular companies, their roadmaps, and their technologies: Toronto-based Xanadu Quantum Technologies (which is making a play for public Nasdaq listing this first quarter of 2026 at an estimated 3.6B$ enterprise valuation through a SPAC deal); and the Palo Alto, California-headquartered PsiQuantum (PSIQ.PVT, with an estimated 7B$ valuation buoyed by a 1$ billion worth Series E funding round in late 2025).
Like our previous roadmap analysis, this won’t be a technical article; it’s a technology and roadmap analysis that brings understandable bites on the underlying technologies, their roadmap evolution, current state, and expected next steps. For a better understanding of what quantum computing is all about, Tom’s Hardware has a more explanatory quantum computing article you can familiarize yourself with first.
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What is Quantum Photonics?
To answer what quantum photonics actually is, we have to start with the most basic: photonics is the use of light to transmit encoded information. The most widespread application of photonics that’s already a part of our infrastructure today materializes through fiber optic cables: within them, light travels at its speed (which matters for latency) and crucially, without energy losses to electrical resistance.
Because light can contain multiple wavelengths (think colors, ranging through the visible spectrum and beyond), information in fiber optic cables can be encoded in multiple paths within the same ray (a technique known as multiplexing) for increased bandwidth.
This classical approach to photonics uses billions of photons (the essential unit of light) in coherent beams, using other elements such as phase and polarization as data carriers. Classical photonics is already a well-known quantity, with multiple applications in both intercontinental information transit, data center interconnects, and more specifically, inter-chip communication.
The transition towards the quantum realm occurs when you stop looking at light as a beam and focus on the singular elements that compose it: photons. Quantum photonics, then, makes use of single-photon sources and single-photon detectors to encode and decode information through the specific strengths of quantum properties: entanglement (where two entangled photons become a coherent system) and superposition (where the universe of possible information values can be contained in a single qubit until interfered with).
(Image credit: IBM)
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