Quantum computers could crack encryption sooner than we thought

Quantum computers capable of breaking modern cryptography may require far fewer qubits than previously believed, according to new research from the California Institute of Technology.

In the study published Monday, Caltech worked with Pasadena-based Oratomic, a quantum computing startup founded by Caltech researchers, to develop a new neutral-atom system in which individual atoms are trapped and controlled with lasers to act as qubits. Doing so could allow a fault-tolerant quantum computer to run Shor's algorithm, which could derive private keys from the public keys used in Bitcoin's elliptic-curve cryptography, with as few as 10,000 reconfigurable atomic qubits.

Oratomic co-founder and CEO Dolev Bluvstein, a visiting associate in physics at Caltech, said advances in quantum computing are accelerating the timeline for practical machines and increasing pressure to migrate to quantum-resistant cryptography.

"People are used to quantum computers always being 10 years away," Bluvstein told Decrypt. "But when you look at where we were a little over ten years ago, the best estimates of what would be required for Shor's algorithm were one billion qubits at a time when the best systems we had in the lab were roughly five qubits."

Today's most common error-correction systems often require about 1,000 physical qubits to create a single reliable, logical qubit, the error-corrected unit used to perform calculations. That overhead has helped push estimates for practical fault-tolerant systems into the million-qubit range, slowing progress toward machines capable of running algorithms that could threaten RSA and elliptic-curve cryptography used by Bitcoin and Ethereum.

Bluvstein noted that current lab systems are already approaching-and in some cases exceeding-6,000 physical qubits. In other words, the cryptography risk may be much sooner than experts previously expected.

"You can really see the system size and controllability increasing over time as the required system size goes down," he said.

Despite this, Bluvstein said a practical quantum computer could emerge before the end of the decade.