A Nobel Prize-winning physicist who helped build Google’s quantum computers warned that Bitcoin may be among the earliest real targets for the technology.
In an interview with CoinDesk, John M. Martinis said that 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 shows where we are right now,” Martinis said, referring to Google’s recent work on quantum threats to cryptography. “It’s not something that has zero probability; people have to deal with this.”
READ: A simple explanation of what quantum computing actually is and why it’s scary 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 that this is one of the issues that must be taken most seriously.
READ: Here’s what it actually means to ‘crack’ bitcoin in 9 minutes with quantum computers
While the idea of quantum computers breaking encryption is often framed as distant or theoretical, Martinis said one of the first practical applications could be far more immediate.
Low-hanging fruit for quantum computing
“It turns out that breaking cryptography is one of the easiest applications of quantum computing because it’s very numerical,” he said. “These are the smaller, easier algorithms. The low-hanging fruit.”
That puts bitcoin, which relies on elliptic curve cryptography, squarely in the firing line, 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 historic design make upgrades slower and more contentious, the Nobel laureate said.
“You can go to quantum-resistant codes” in banks and other systems, Martinis said. “Bitcoin is a little bit different, and that’s why people should be thinking about this right now.”
The concern centers on a specific window of vulnerability. When a bitcoin transaction is broadcast, its public key becomes visible before it is confirmed on-chain, Martinis explained. A powerful quantum computer could, in theory, use this 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 carrying out such an attack remains one of the most difficult technical challenges in modern science.
“I think it’s going to be harder to build a quantum computer than people think,” he said, pointing to major hurdles in scaling, reliability and error correction.
No need for inaction
Estimates of when cryptographically relevant quantum machines may appear vary widely. Martinis suggested a rough five- to 10-year window, but cautioned 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 within 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 practices.
For bitcoin developers and investors alike, the message is becoming harder to ignore.
“The crypto community needs to plan for this,” Martinis said. “It’s a serious problem that needs to be addressed.”
Martinis is a 2025 Nobel Prize-winning physicist recognized for his work on macroscopic quantum phenomena and known for leading Google’s quantum hardware program, including the 2019 “quantum supremacy” experiment. He is currently the CTO and co-founder of Qolab, a hardware company developing utility-scale superconducting quantum computers.
