Scientists have developed a new method to improve the efficiency of quantum error correction using ‘cat codes’, a promising approach to building fault-tolerant quantum computers. Ari John Boon and Olivier Landon-Cardinal, from the University of Oxford, alongside Nicolás Quesada, demonstrate a generalised all-optical protocol for correcting errors in these codes, extending it to higher orders than previously possible. This research significantly reduces the number of iterations needed to achieve high-fidelity correction, a third-order cat code requiring seventy times fewer iterations than a first-order one for a target channel fidelity of 99.9% over a channel with 1 dB of loss, although at a moderate increase in the mean photon-number. The team’s probabilistic…