Microsoft on June 3, 2026, unveiled Majorana 2, a topological quantum chip whose qubits are 1,000 times more reliable than its predecessor - and the company now expects to have a scalable, commercially viable quantum computer ready by 2029, cutting its original timeline in half. For the Bitcoin network, that date compresses what has long been treated as a distant theoretical risk into a concrete engineering deadline.
The chip's breakthrough comes from a materials change. Where Majorana 1 used an aluminum superconductor, Majorana 2 uses lead - the same material used to shield radiation in hospitals and industrial settings. In a quantum system, a lead superconductor helps insulate fragile qubits from cosmic disturbances that otherwise cause errors. The result: a mean qubit lifetime of 20 seconds, with some instances lasting up to one minute. Competing approaches typically measure qubit lifetimes in microseconds. Individual operations run in one microsecond. Each qubit is 1/100th of a millimeter - a size that makes scaling more tractable.
"We need to make improvements each year that will get us closer to delivering a computer that we believe will have massive commercial and societal value," said Chetan Nayak, Microsoft Technical Fellow. "Where are we relative to last year? We're 1,000 times better."
The Bitcoin threat runs through elliptic-curve cryptography (ECC), the mathematical foundation of Bitcoin's digital signatures. A wallet's public key, once exposed on-chain, can in theory be used to derive its private key - and thus drain it - if an attacker has access to a sufficiently powerful quantum computer running Shor's algorithm. Wallets that have broadcast a transaction, or that use older Pay-to-Public-Key (P2PK) output formats, have their public keys visible on the blockchain. Researchers have estimated that a substantial portion of the circulating BTC supply sits in such addresses, though the exact figure depends on methodology and current BTC price.
The context for 2029 is a series of converging milestones. Google unveiled its Willow quantum chip on December 9, 2024, demonstrating that error rates fall rather than rise as the system scales - cracking a core challenge in quantum error correction that had persisted for nearly 30 years. Separately, a 2023 paper from researchers using a silicon-photonics-inspired architecture (arXiv:2306.08585) found that breaking a 256-bit elliptic curve key might require as few as 6,000 modules - far fewer resources than earlier estimates assumed. Google has projected Q-Day, the point at which a quantum computer can break current encryption, by 2032; other researchers have cited 2030 as plausible. Majorana 2 pulls that window earlier.
What distinguishes Majorana 2 from prior quantum efforts is not just the hardware but how it was built. Microsoft used its Discovery platform - a suite of agentic AI tools designed to automate scientific workflows - to manage qubit measurements, optimize fabrication processes, and surface manufacturing flaws that would otherwise remain invisible. The team used AI to find the right "recipe" for adding impurities to the chip's crystalline structure atom by atom, a process that previously required extensive manual experimentation. "Agentic AI has permeated almost everything we do," Nayak said. "It's just become kind of a very natural part of our workflow."
The quantum computing and cryptography communities have not been standing still. Quantum-resistant signature schemes - including lattice-based algorithms standardized by NIST in 2024 - are under active development, and several crypto projects have begun research into post-quantum migration paths for Bitcoin. The challenge is the coordination problem: moving the Bitcoin network to a new signature scheme requires broad consensus and careful management of the transition window, during which legacy addresses remain exposed.
Majorana 2 does not break Bitcoin's encryption. A chip with commercial viability in 2029 is not the same as one capable of attacking a 256-bit elliptic curve key - that still requires millions of reliable physical qubits in a fault-tolerant configuration, and the exact qubit count needed depends on architectural choices that remain active research. What it does is narrow the distance between here and there. A year ago the consensus was that Q-Day was a 2030s problem. With Microsoft now on a 2029 trajectory for a scalable system, and the resource estimates for breaking ECC lower than previously thought, the gap between "theoretical" and "operational" risk keeps shrinking.
The question for Bitcoin is whether quantum-resistant cryptography moves faster than quantum hardware does.
Note for editorial review: The $461B figure cited in the brief could not be sourced to a primary document during reporting. Multiple analyses of the Bitcoin UTXO set have estimated the quantum-exposed portion of the supply in the range of several million BTC, with valuations varying by BTC price and methodology - but I cannot attach a specific dollar figure to a verifiable primary source. I have reported the exposure mechanism accurately and noted the research context. If the editorial team has a specific source for the $461B figure, I can insert it with attribution. Publishing a specific dollar amount without a traceable source would be a factual error.