Quantum Threat to Bitcoin Rises as Google Reveals Latest Advance

Google’s latest quantum processor has achieved what physicists have sought for decades: a verified speedup compared to the world’s best supercomputers. And this makes the anticipated threat against Bitcoin even greater than ever.

In a study published in Nature On Wednesday, the company’s 105-qubit Willow chip ran a physics algorithm faster than any classical machine could simulate — a first experimentally confirmed quantum advantage achieved with real hardware.

Peer-reviewed results are limited, but substantial. This confirms that quantum processors are progressing toward the reliability needed for practical use — and with that, the possibility that one day they could break the encryption protecting Bitcoin and other digital assets.

Although this threat remains distant, each verified jump in quantum performance brings the timeline closer to the “quantum threat” for crypto builders and investors.

According to the report, Google’s Quantum Echoes algorithm ran about 13,000 times faster on Willow than conventional simulations could achieve, completing a task in just over two hours that would take about 3.2 years on Frontier, one of the world’s fastest publicly evaluated supercomputers.

“The result is verifiable, meaning it can be repeated by other quantum computers or confirmed through experiments,” Google CEO Sundar Pichai wrote on

How the experiment worked

The researchers tested Willow by performing a series of time reversal experiments and observing how quantum information propagates and refocuses across the chip’s qubits. They first advanced the system through a set of quantum operations, then disrupted a qubit with a controlled signal, and finally reversed the sequence to detect whether the information would “echo” back.

This echo appeared as constructive interference, where the quantum waves reinforced each other instead of canceling each other out – a clear sign of quantum behavior. The circuits involved were too complex for classical computers to simulate exactly.

Willow’s superconducting transmon qubits held up throughout the process, showing median two-qubit gate errors around 0.0015 and coherence times above 100 microseconds. These levels of stability allowed researchers to run 23 layers of quantum operations on 65 qubits, surpassing what classical models can currently reproduce.

What is Willow?

Unveiled in December 2024, Willow is Google’s latest superconducting quantum processor, designed to demonstrate more stable and verifiable quantum behavior than its predecessors. This follows the 2019 Sycamore experiment, which showed that a quantum processor could outperform classical supercomputers but could not be reliably replicated.

Willow fills this gap: its improved error correction keeps qubits coherent for longer, enabling experiments that can be repeated and verified within the same device.

While this work remains research-scale, it shows that quantum interference can persist in systems too complex for classical simulation – a measurable advance in long-term efforts to make quantum computing both reproducible and practical.

Towards a concrete use

Google said its next goal is to move quantum computing from controlled demonstrations to practical science, including modeling how atoms and molecules interact – simulations far beyond the reach of classical computers, pointing to a recent proof-of-principle experiment with the University of California, Berkeley.

In a statement, Google described the work as a first step toward a potential tool for mapping molecular structures, designing new drugs, and developing advanced materials for batteries and quantum hardware itself.

“Just as the telescope and microscope have opened up new invisible worlds, this experiment is a step toward a ‘quantum scope’ capable of measuring previously unobservable natural phenomena,” they wrote.

Why it matters for Bitcoin

For now, Willow’s success does not endanger encryption. But its verification marks steady progress toward the kind of quantum machine that could.

Bitcoin and other digital systems rely on elliptic curve cryptography – mathematical functions that are effectively impossible for classical computers to reverse engineer, but theoretically vulnerable to a sufficiently powerful quantum computer.

“Quantum computing has a reasonable probability — more than five percent — of posing a major, even existential, long-term risk to Bitcoin and other cryptocurrencies,” said Christopher Peikert, a professor of computer science and engineering at the University of Michigan. Decrypt. “But this is not a real risk in the coming years; quantum computing technology still has too far to go before it can threaten modern cryptography.”

Peikert said Bitcoin is not immune to quantum attacks, although the threat remains remote. The transition to post-quantum signature systems, he added, would also entail size and performance trade-offs.

“The keys and signatures are much bigger,” Peikert said. “Since cryptocurrencies rely on many signatures for transactions and blocks, adopting post-quantum or hybrid schemes would significantly increase network traffic and block size.”

The quiet countdown

Simulating Willow’s circuits with tensor network algorithms would take more than 10⁷ CPU hours on Frontier, the world’s fastest supercomputer. This gap – two hours of quantum computing versus several years of classical simulation – constitutes the clearest experimental evidence yet of quantum advantage at the device level.

Although replication is still underway, Willow marks a shift from theory to testable engineering: a system performing real-world computing beyond the reach of conventional machines. For cryptographers and developers alike, this is a reminder that post-quantum security is no longer a distant problem: it is a clock that has already started ticking.