Xanadu and HyperLight's quantum switches now lose 7 mdB, the ceiling Xanadu's fault-tolerance design set
Optical switch loss in Xanadu's photonic quantum chips is down to 7 mdB from 20 mdB, the per-switch ceiling its 2025 Nature paper set for fault tolerance.
- Format
- News
- Published
- November 11, 2026
- Length
- 1,241 words
Optical switch loss, the light a photonic quantum computer bleeds at every routing switch, is down to 7 millidecibels in chips from Xanadu and HyperLight, the two companies said on November 10, 2026. That matches the per-switch ceiling Xanadu's own published design set for fault-tolerant machines.
Key points
- Xanadu (Nasdaq/TSX: XNDU) and HyperLight say their switches now lose 7 mdB of light each, down from the 20 mdB the two companies reported in 2025.
- The switches were made on a high-volume wafer manufacturing line on HyperLight's thin-film lithium niobate (TFLN) Chiplet platform, which the companies say showed excellent yield and repeatability.
- Xanadu's January 2025 Nature paper found that with as many as 15 switches in its deepest optical path, each switch could lose no more than about 7 mdB.
- Xanadu's Aurora machine, described in that paper, used HyperLight TFLN switches with an average insertion loss of 0.19 dB, or 190 mdB (Nature).
- Xanadu CEO Christian Weedbrook says the result is ten times lower than the closest competitor's latest published figure; Xanadu's copy of the release links that comparison to a 2024 PsiQuantum preprint.
Why does optical switch loss matter in a photonic quantum computer?
Because a lost photon is a lost qubit, and it cannot be put back. In a photonic machine, switches route the photons that carry quantum information, and quantum signals cannot be boosted the way ordinary optical signals are without destroying the quantum state. Xanadu's 2025 Nature paper on its Aurora system calls optical loss "the dominant and most challenging hurdle" to fault tolerance. (For how qubits differ from ordinary bits, see our primer on emerging hardware technology.)
The loss adds up along a path. In the architecture the paper lays out, light can pass through as many as 15 Mach–Zehnder switches on its longest route, so the per-switch figure has to be tiny: about 7 mdB, the paper calculates, even before counting any other component (Nature).
| Switch | Insertion loss per switch | Source |
|---|---|---|
| Aurora refinery chips, HyperLight TFLN | 0.19 dB (190 mdB) | Nature, January 2025 |
| Process work reported in the same paper | 30 mdB | Nature, January 2025 |
| PsiQuantum barium titanate switch, phase-shifter section (2024 preprint) | about 100 mdB | arXiv 2404.17570 |
| Xanadu and HyperLight, 2025 result | 20 mdB | Xanadu press release |
| Xanadu and HyperLight, November 2026 | 7 mdB | Xanadu press release |
| Ceiling per switch for a 15-switch path | about 7 mdB | Nature, January 2025 |
What did Xanadu and HyperLight report?
They report an optical switch that loses 7 mdB, close to a third of their 2025 figure. The companies say they reached it on HyperLight's TFLN Chiplet platform on a high-volume wafer manufacturing line, and that the parts showed excellent yield and repeatability. Xanadu says lower switch loss keeps quantum states intact, prevents lost qubits and lets a photonic network grow without a matching rise in laser power or spare hardware.
“This notable switch insertion loss milestone indicates that Xanadu’s quantum-compatible switches are ready to ramp to production, bringing scalable quantum hardware and utility-scale quantum computing (USQC) one step closer to reality.”
— Christian Weedbrook, Founder and Chief Executive Officer, Xanadu
“Achieving 7 mdB switch loss, nearly 3x lower than our previous benchmark set just over a year ago and 10x lower than our closest competitor’s most recent published result, is a major hardware milestone that enhances performance and reduces overhead for utility-scale systems,”
— Christian Weedbrook, Founder and Chief Executive Officer, Xanadu
The competitor result Xanadu points to is PsiQuantum's April 2024 preprint, A manufacturable platform for photonic quantum computing, which reports about 100 mdB of insertion loss for the phase-shifter section of its barium titanate Mach–Zehnder switches.
Weedbrook says the company expects the gain to show up as better manufacturing economics and a smaller footprint, and that the low-loss technology could also be useful in data centers as they get faster and use more energy.
What does a 7 mdB switch mean for hardware engineers?
Our analysis: the number that matters is the one Xanadu's own architecture asked for. Its 2025 paper put the per-switch budget at about 7 mdB, and the new result reaches it. The supplier is not new either: Aurora's refinery chips were already HyperLight TFLN parts made on a semiconductor volume line, so the gain comes from the same platform Xanadu already builds on. For engineers outside quantum, HyperLight says that Chiplet platform already serves AI data center and telecom optics. Quantum computing also led the answers when we asked experts which CPU technologies will shape future computing.
“The same platform that powers high-volume AI data centers and telecom networks has now delivered a record-setting 7 mdB switch loss for quantum computing with Xanadu, a testament to our platform’s ability to meet the most exacting demands.”
— Mian Zhang, CEO, HyperLight
Frequently asked questions
What is a millidecibel of insertion loss?
A millidecibel (mdB) is a thousandth of a decibel. Insertion loss is how much light a component absorbs or scatters as the light passes through it, so 7 mdB means each switch keeps almost all of the light it routes.
What is thin-film lithium niobate?
Thin-film lithium niobate (TFLN) is a photonic chip material whose electro-optic properties let a voltage switch or modulate light quickly. HyperLight builds its Chiplet platform on it for data center, telecom and quantum uses.
Who makes the switches?
HyperLight Corporation makes them on its TFLN Chiplet platform, working with Xanadu, which designs the photonic quantum computers they go into.
Is Xanadu a public company?
Yes. Xanadu, founded in 2016, trades on Nasdaq and the Toronto Stock Exchange under the ticker XNDU, and says it was the first pure-play photonic quantum computing company to list.
Sources
- Xanadu and HyperLight press release on 7 mdB optical switch loss: press release from Xanadu Quantum Technologies via GlobeNewswire, 10 November 2026.
- Scaling and networking a modular photonic quantum computer: Xanadu's peer-reviewed paper on the Aurora system and its loss budgets, Nature 638, published 22 January 2025.
- A manufacturable platform for photonic quantum computing: PsiQuantum's preprint on arXiv, 26 April 2024, the competitor result Xanadu's release links to.
- Xanadu's copy of the release: the same announcement on Xanadu's press page, with its links.
- Xanadu: the company's website.
- HyperLight: the company's website.