Recent research indicates that breaking today’s strongest encryption won’t require the millions of qubits previously estimated. A quantum computer with just 10,000 qubits could be sufficient to compromise widely used cryptographic systems, threatening banking data, private communications, and digital security as a whole. This development accelerates the timeline for transitioning to post-quantum cryptography.
The Shrinking Qubit Threshold
For decades, the assumption was that quantum computers needed immense scale—millions of qubits—to break encryption standards like RSA. The new study, uploaded to arXiv, challenges this view, citing rapid advancements in quantum error correction (QEC) and the growing maturity of neutral-atom quantum computers. These improvements mean fewer qubits are needed for a fault-tolerant system capable of cracking modern encryption.
The core of the threat lies in algorithms like Shor’s algorithm, developed in 1994. This quantum algorithm efficiently factors large numbers, the foundation of RSA encryption. While classical computers struggle with this task, a quantum computer can theoretically solve it in seconds. Earlier estimates required millions of qubits to execute Shor’s algorithm; now, the threshold is as low as 10,000.
Neutral Atoms and Error Correction
The shift comes down to two key breakthroughs. First, neutral-atom quantum computers – using individual, supercooled atoms held by lasers – are proving more stable and scalable than traditional superconducting qubits. Second, QEC is making qubits more reliable.
Unlike classical bits, qubits are prone to errors. To counteract this, scientists use logical qubits, collections of entangled physical qubits that ensure data persistence even if some fail. QEC is improving rapidly, meaning that fewer physical qubits are needed to create one reliable logical qubit. Some designs now require as few as five physical qubits per logical qubit, a dramatic reduction.
Encryption at Risk: Timelines and Algorithms
The study modeled the performance of current and near-future quantum computers against three key encryption algorithms:
– RSA-2048 : The industry standard for digital certificates. A 26,000-qubit quantum computer could crack it in as little as seven months.
– ECC-256 : Used to secure internet traffic and cryptocurrency. A system with 10,000-26,000 qubits could break it within ten days.
– Shor’s algorithm : The benchmark for quantum computing. A 11,961-qubit system could solve it.
The researchers found that a parallelized architecture with roughly 102,000 qubits could crack RSA-2048 in under 100 days. These projections are based on current QEC techniques; further improvements in qubit fidelity or algorithmic compression could shrink the required qubit count even more.
The Urgent Need for Post-Quantum Cryptography
The findings underscore the need for immediate action. Google engineers have warned that the world has less than three years to migrate to post-quantum cryptography – encryption standards designed to resist quantum attacks. The study emphasizes that while substantial engineering challenges remain, the theoretical possibility of building a cryptographically relevant quantum computer is no longer distant.
“Although substantial expertise, experimental development effort, and architectural design are required, our theoretical analysis suggests that a neutral atom system capable of implementing Shor’s algorithm could be constructed.”
The transition to post-quantum cryptography is not optional; it’s a race against the accelerating capabilities of quantum computing. The window of opportunity to secure digital infrastructure is closing rapidly.
