Falling Qubit Thresholds Bring Quantum Risk to Crypto Into Sharper Focus
Advances in quantum computing are rapidly lowering the theoretical barrier to breaking blockchain encryption, raising urgency around the crypto industry’s transition to quantum-resistant security.
A new study from Caltech and quantum startup Oratomic suggests that roughly 26,000 qubits could be enough to crack ECC-256—the elliptic curve cryptography securing Bitcoin and Ethereum—in about 10 days. The same research indicates that compromising crypto wallets may require as few as 10,000 physical qubits, a steep drop from earlier estimates that ran into the hundreds of thousands.
Qubits, the building blocks of quantum computers, reflect system scale rather than speed, making them a key benchmark for measuring computational capability.
The findings were published on the arXiv preprint server alongside a Google Quantum AI paper that estimated fewer than 500,000 qubits would be needed to break similar encryption. The Oratomic team builds on Google’s quantum circuit designs, showing that a neutral-atom approach—where laser-controlled atoms act as qubits—could execute these attacks far more efficiently.
Taken together, the research highlights how quickly projections are shifting. Over the past two decades, estimates for running Shor’s algorithm—the quantum technique used to break public-key cryptography—have dropped dramatically, from around one billion qubits to roughly 10,000.
This rapid compression is helping define clearer timelines for potential threats. Under the study’s assumptions, a sufficiently advanced quantum system could derive private keys from public addresses within days, opening the door to wallet compromise.
Traditional systems appear somewhat more resilient. Breaking RSA-2048, widely used in financial infrastructure, would require closer to 102,000 qubits and months of computation, making elliptic curve cryptography a comparatively easier target due to its smaller key sizes.
The research also suggests that near-instant “on-spend” attacks—where a quantum machine intercepts transactions in real time—remain unlikely for now. However, longer-term risks persist, particularly for funds held in older or reused wallet addresses, including millions of bitcoins that could be exposed.
The study carries some caveats. All nine authors have financial ties to Oratomic, with most employed by the company, positioning the work as both research and a validation of its technological approach.
Even so, the broader implication is becoming increasingly difficult to ignore. As the cost and scale required for quantum attacks continue to decline, the central question for the crypto industry is shifting from if these systems can break existing security to whether defenses can be upgraded before that point is reached.
