A Verified Quantum Speed-Up
Google has achieved a verified quantum speed-up with its 105-qubit Willow processor. The system completed a physics computation roughly 13,000 times faster than the frontier supercomputer, confirming a long-sought “quantum advantage.” While the breakthrough is a scientific progress, it also revives concerns over Bitcoin’s cryptographic security.
According to Google’s report, Willow executed the Quantum Echoes algorithm, completing a complex simulation in just over two hours. The same task would take Frontier, one of the fastest classical supercomputers, about 3.2 years to process. Google CEO Sundar Pichai said on X that the result is “verifiable and repeatable,” emphasizing it as a milestone toward practical quantum applications.
The test involved running time reversal experiments, where researchers drove the system forward, unsettled one qubit, and then reversed the sequence. The experiment detected “quantum echoes” through constructive interference, a clear indicator of quantum coherence. These circuits were too intricate for classical models to reproduce accurately.
Notably, Willow’s superconducting transmon qubits maintained median two-qubit gate errors near 0.0015 and coherence times above 100 microseconds. This stability allowed the team to operate 23 layers of quantum logic across 65 active qubits, beyond classical simulation capacity.
From Sycamore to Willow
Willow follows Google’s earlier Sycamore processor, which in 2019 first demonstrated quantum advantage but lacked reproducibility. This new chip closes that gap with improved error correction and longer qubit stability, enabling consistent verification within a single device.
Unveiled in December 2024, Willow was designed for reliability and measurable quantum behavior. According to Google, the breakthrough is a move from isolated demonstrations toward engineering-ready systems. Researchers now aim to apply quantum computing to model atomic and molecular interactions tasks unattainable by even the fastest traditional hardware.
The company, in collaboration with the University of California, Berkeley, has already conducted proof-of-principle experiments to simulate chemical reactions. Google described these advances as early steps toward quantum-assisted design of medicines, materials, and batteries. Hartmut Neven, Google’s vice president of engineering, said the company hopes to see “real-world applications” within five years.
Implications for Bitcoin and Encryption
While Willow’s experiment does not yet threaten encryption, experts say it narrows the timeline for potential risk. Bitcoin relies on elliptic-curve cryptography, a system considered secure against classical computation but theoretically vulnerable to a sufficiently advanced quantum computer.
Christopher Peikert, professor of computer science at the University of Michigan, told reporters that quantum computation has “a reasonable probability of posing a long-term risk to Bitcoin.” However, he added that such a threat remains at least several years away.
Peikert noted that moving Bitcoin to post-quantum cryptography would create new challenges. “Keys and signatures are much larger,” he said, explaining that this would increase network data and block sizes, affecting transaction throughput.
Kostas Kryptos Chalkias, co-founder and chief cryptographer at Mysten Labs, supported that concern. He said there is no evidence that any computer today, even a classified one, can break modern cryptography. Insisting that we’re at least 10 years away from that.
Still, Willow’s verified results show progress toward the kind of fault-tolerant quantum system that could make such attacks possible in the future. Google’s achievement, two hours of computation versus several years of classical simulation, is the clearest experimental proof yet of device-level quantum advantage.
That gap shows how quickly quantum hardware is moving from theoretical constructs to testable machines. For developers and cryptographers, each verified milestone changes the conversation from speculation to preparation, pushing Bitcoin’s post-quantum transition higher on the industry’s agenda.
Future Outlook
Experts agree that fully fault-tolerant quantum systems capable of breaking cryptographic protocols will require hundreds of thousands, possibly millions, of qubits. Professor Winfried Hensinger of the University of Sussex noted that Google’s experiment is limited to a narrow scientific task but proves steady progress toward more capable architectures.
Michel Devoret, Google’s chief scientist and recent Nobel laureate in physics, described the result as “another step toward full-scale quantum computation.” The company views Willow as a foundation for future systems capable of simulating molecular structures and advancing materials science.
Meanwhile, Google’s verified quantum advantage may not yet endanger encryption, but it redefines how close that reality could be. Each successful test narrows the gap between controlled research and practical capability, signaling a new era where quantum engineering begins to challenge digital security assumptions.