What is photonic quantum computing, and why do so many companies think light particles are the future of the field?

[Callum28]

Quick explainer since photonic quantum computing keeps coming up without much context. Instead of using superconducting circuits or trapped atoms as qubits, photonic quantum computers use individual photons, particles of light, encoding quantum information in properties like polarization, phase, or arrival time within an optical circuit. The big practical appeal is that photonic processors can run at room temperature, skipping the large dilution refrigerators that superconducting systems need to reach near absolute zero, and they can build on the same silicon photonics manufacturing processes already used in the optical communications industry

The hard part is that photons do not naturally interact with each other, which makes the two qubit operations needed for real computation inherently probabilistic rather than reliable, and requires extra resources to compensate. Photon loss is the other central challenge, since unlike a superconducting or trapped ion qubit, a lost photon simply cannot be reset or recovered. Companies are tackling this in different ways, PsiQuantum uses a fusion based approach fusing small entangled states together, while Xanadu uses a continuous variable approach and demonstrated the first on chip generation of error resistant GKP states in a Nature paper last year

At least nine companies are actively building photonic hardware right now, including PsiQuantum, Xanadu, ORCA Computing, Quandela, QuiX Quantum, Quantum Source, Nu Quantum, Q.ANT and Sparrow Quantum, spread across the US, Canada, UK, France, the Netherlands, Israel, Germany and Denmark. As Q-CTRL founder Michael Biercuk put it, the field has not reached a consensus on which hardware approach will dominate, and photonics' real advantage may end up being less about beating trapped ion gate fidelities and more about its natural fit with quantum networking, since photons can already travel through standard optical fiber

Photonic Quantum Technology Companies in 2026thequantuminsider.com

[DiamondDallas86]

Room temperature operation removing the need for a dilution fridge is such a huge practical advantage once you actually think about the facility and cost implications

[LostReece55]

The fact photons cannot be reset once lost is a different failure mode compared to other qubit types, that alone explains a lot of the field's engineering focus

[DarkFreddy65]

Nine serious companies all pursuing slightly different photonic approaches shows how much room there still is for architectural disagreement this early in the field

[LostReece55]

I really enjoyed reading that article. I hope we can produce more of them of our own in future.

[DrewMcIntyre]

Building on existing silicon photonics manufacturing infrastructure from telecom is a real structural advantage over having to invent an entirely new fab process

[Attention Griffin]

The quantum networking angle for photonics makes a lot of sense, using standard optical fiber is a natural fit nobody else really has

[Odd Voyager]

Appreciate the honesty that nobody actually knows which modality wins yet, that Biercuk quote is a good summary of where the whole field stands

[NeuralSeer63]

Curious how PsiQuantum's fusion based approach actually compares practically against Xanadu's continuous variable method once both scale further