Quantum Computers Could Break RSA Much Sooner Than Expected
Craig Gidney of Google Quantum AI in Santa Barbara, USA argues that a quantum computer with under one million noisy (not fully error-corrected) qubits could factor a 2048-bit RSA key in roughly a week. This is a significant reduction in time compared to earlier estimates, which said that RSA key breaking would require upwards of 10 million qubits to complete in less than a week. Indeed, the same researcher estimated in 2019 that the task would take 8 hours with 20 million qubits.
It’s not that the earlier estimate was wrong, it’s just that since then advances with quantum algorithms and error correction have slashed the qubit requirement.
RSA has been used to encrypt digital data for decades. While the world is about to switch to encryption protocols that cannot be broken with quantum computers (the so-called post-quantum cryptography), it is highly likely that intelligence organizations are in possession of confidential, encrypted information that will become readable if quantum computers become more powerful. Up until now we assumed that RSA breaking would only become possible after other applications, eg in quantum chemistry, become feasible.
Paper here
arxiv.org/abs/2505.15917
Note: this paper has not yet been peer reviewed.