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qBitTensor Labs Live — September 18, 2025

September 18, 202543:07

Subnet 63 stability improvements, a 3x speedup in peaked circuit generation through a novel obfuscation-based reuse technique, Shor's challenge timeline, and dispatches from Quantum World Congress including insights on national quantum strategies and the race toward 50 logical qubits.

Stability and Fairness on Subnet 63

We shipped a round of stability updates targeting the miner experience on Subnet 63. The headline change is an initial handshake mechanism: when a new miner registers, the validator now reaches out to ask what difficulty level they want before issuing a circuit. Previously, new miners would receive a minimum-difficulty circuit and then wait through increasingly long revisit windows — sometimes 20-plus hours — before getting the difficulty they actually wanted. The immunity period has also been extended to give miners more time to land initial solutions.

We also tackled a persistent out-of-memory issue during peaked circuit generation at higher qubit counts (37-39). When generation crashed, the NVIDIA driver would hold onto GPU memory even after the process died, causing downstream failures for other miners. A new step-down mechanism ensures that if a validator repeatedly fails at a given qubit size, it permanently drops to a lower maximum so every miner gets served a circuit rather than being skipped.

Peaked Circuit Generation: 3x Faster via Obfuscation Reuse

Will (BongoCatFeynman) presented a novel approach to speeding up peaked circuit generation. Rather than generating every circuit from scratch, we now reuse previously generated circuits by applying randomized obfuscations — inserting pairs of random single-qubit unitaries and their adjoints around two-qubit gates, then adding randomized bit flips to the output layer. The result is a distinct circuit that preserves the peaking property but can be produced at least three times faster. This replaces the earlier circuit-stitching approach, which turned out to be too easy to break. The code was published on a public branch and went live the following Monday.

Shor's Challenge on the Horizon

The technical paper for the Shor's challenge is complete, the generation code is written and tested, and integration into the subnet is ready. We have been holding off on launch to avoid introducing too much change at once while peaked circuits are being stabilized. Our best estimate is a Shor's launch in two to three weeks, with the option to release the paper earlier if there is enough community interest.

Open Quantum Waitlist and End-to-End Progress

The Open Quantum waitlist is now live — prospective users can sign up and share their background, experience level, and intended use cases. Behind the scenes, we are working toward a first end-to-end test that routes a request from the web portal through to an actual quantum computer and back. That milestone was expected by the end of the following week, though a production-ready launch still requires significant surrounding work.

Dispatches from Quantum World Congress

Bob reported live from Quantum World Congress, where several themes stood out. The CTA president framed quantum as "the technology that will shape the next decade." Quantinuum's CEO committed to delivering 50 logical qubits commercially this year — a threshold where real-world problems start becoming solvable on the DARPA scatterplot. Naftali Bennett, former prime minister of Israel, delivered a striking warning: Adi Shamir (the "S" in RSA) told him that once quantum computers scale, RSA encryption "might as well be plain text." Bennett also highlighted nation-states stockpiling encrypted data today at near-zero cost, waiting for the ability to decrypt it. Forty-one countries now have quantum policies, up from twelve a year ago. And Quantum Rings, our partner, appeared on NVIDIA's deck at the event.

Subnet Merging and Winner-Take-All

We addressed two recurring community topics. On subnet merging: we find the technology interesting but are not taking on that additional risk right now given the number of moving pieces across SN48, SN63, and Open Quantum. Letting other subnets go first will help de-risk the decision if we revisit it later. On winner-take-all scoring for SN63: the team is unanimously in favor of the concept. We see it fitting naturally into Phase 3 of the roadmap, possibly earlier, and are exploring variations such as "winner takes most" with smaller offset pools to help miners cover costs while competing.