Get a special 35% discount* on an annual digital subscription to The Economist at https://www.economist.com/Sabine *20% in the UK, Latin America, and India. Photonic computers are processors that use light – not electricity – to complete their calculations. In theory, photonic computers are both faster and more efficient than today’s silicon chips, and – according to the headlines – the technology is making serious progress. Does the technology live up to the hype? Let’s take a look at the