Bitcoin quantum threat is real and closer than it looks, says Nobel physicist

A Nobel Prize–winning physicist who helped build Google’s quantum computers warned that Bitcoin BTC$68,399.76 may be among the earliest real-world targets of the technology.

In an interview with CoinDesk, Dr. John M. Martinis said recent Google research showing how a quantum computer could break bitcoin encryption in minutes should be taken seriously.

“I think it’s a very well-written paper. It lays out where we are right now,” Martinis said, referring to Google’s latest work on quantum threats to cryptography. “It’s not something that has zero probability; people have to deal with this.”

READ: A simple explainer on what quantum computing actually is, and why it is terrifying for bitcoin

The Google paper outlines how a sufficiently advanced quantum computer could derive a bitcoin private key from its public key, potentially within minutes, dramatically reducing the computational barrier that currently secures the network, Martinis highlighted, adding this is one of the issues that must be taken most seriously…

READ: Here’s what ‘cracking’ bitcoin in 9 minutes by quantum computers actually means

While the idea of quantum computers breaking encryption is often framed as distant or theoretical, Martinis said one of the first practical applications may be far more immediate.

Lowest hanging fruit for quantum computers

“It turns out that breaking cryptography is one of the easier applications for quantum computing, because it’s very numeric,” he said. “These are the smaller, easier algorithms. The low-hanging fruit.”

That places bitcoin, which relies on elliptic curve cryptography, directly in the line of fire, Martinis suggested, confirming what the Google paper warns.

Unlike traditional financial systems, which can migrate to quantum-resistant encryption standards, bitcoin faces a more complex challenge. Its decentralized structure and historical design make upgrades slower and more contentious, the Nobel Prize winner said.

“You can go to quantum-resistant codes” in banking and other systems, Martinis said. “Bitcoin is a little bit different, which is why people should be thinking about this right now.”

The concern centers on a specific vulnerability window. When a bitcoin transaction is broadcast, its public key becomes visible before it is confirmed onchain, Martinis explained. A powerful quantum computer could, in theory, use that window to derive the corresponding private key and redirect funds before final settlement, he noted.

However, Martinis cautioned against assuming the threat is imminent. Building a quantum computer capable of executing such an attack remains one of the hardest engineering challenges in modern science.

“I think it’s going to be harder to build a quantum computer than people are thinking,” he said, pointing to major hurdles in scaling, reliability and error correction.

No reason for inaction

Estimates for when cryptographically relevant quantum machines could emerge vary widely. Martinis suggested a rough five- to ten-year window, but warned that uncertainty is not a reason for inaction.

“Given the serious consequences, you deal with it. You have time, but you have to work on it,” he said.

The warning highlights a growing shift inside the quantum research community, where scientists are increasingly flagging risks to existing cryptographic systems while withholding sensitive technical details — a strategy borrowed from traditional cybersecurity disclosure practices.

For bitcoin developers and investors alike, the message is becoming harder to ignore.

“The crypto community has to plan for this,” Martinis said. “It’s a serious issue that has to be dealt with.”

Martinis is a 2025 Nobel Prize–winning physicist recognized for his work on macroscopic quantum phenomena and is widely known for leading Google’s quantum hardware program, including the 2019 “quantum supremacy” experiment. He is currently CTO and co-founder of Qolab, a hardware company developing utility-scale superconducting quantum computers.