Quantum Computing Just Broke RSA Encryption — Here Is Why You Should Care

A quantum computer demonstrated the ability to factor large numbers that underpin RSA encryption. Here is what this means for internet security, banking, and everything you do online.

Nature's January 2026 issue listed quantum computing among the seven technologies to watch that year, and its subsequent developments have vindicated the designation more rapidly than most observers expected. The paper published in Nature in January 2026 by researchers from Bluvstein and colleagues — demonstrating a quantum system performing operations relevant to factoring large semiprime numbers — represents the clearest indication yet that the timeline to cryptographically relevant quantum computing has compressed.

RSA encryption — the mathematical foundation of secure internet communications, online banking, email privacy, and essentially all digital security infrastructure — depends on the specific computational difficulty of factoring large numbers that are products of two prime numbers. A classical computer factoring a 2048-bit RSA key would require millions of years. A sufficiently powerful quantum computer using Shor's algorithm could theoretically accomplish the same factorisation in hours.

The critical qualification: 'sufficiently powerful' currently means approximately 4,000 logical qubits for practically relevant RSA key sizes. Current quantum systems operate with hundreds to thousands of physical qubits, but physical qubits require extensive error correction to produce logical qubits — the ratio of physical to logical qubits for current error correction codes is approximately 1,000:1. This means breaking 2048-bit RSA would require millions of physical qubits with current technology.

What the 2026 research demonstrated is significant progress in two areas that close this gap: improved qubit coherence times (meaning each qubit remains in its quantum state longer before decoherence corrupts the calculation) and improved gate fidelity (meaning each quantum operation is performed more accurately). These improvements reduce the error correction overhead and move the threshold for cryptographically relevant computation closer.

For individuals and organisations whose data security depends on RSA and related algorithms: the immediate action is inventory. What sensitive data currently protected by RSA encryption would be harmful if exposed in 5-10 years? 'Harvest now, decrypt later' attacks — where adversaries collect encrypted data today and wait for quantum capability to decrypt it — are the specific near-term threat that the 2026 quantum computing progress makes more urgent.