Artist’s impression of the quantum photonic chip, showing the waveguide circuit (in white), and the voltage-controlled phase shifters (metal contacts on the surface). Photon pairs become entangled as they pass through the circuit. The fundamental resource that drives a quantum computer is entanglement—the connection between two distant particles which Einstein famously called 'spooky action at a distance'. The Bristol researchers have, for the first time, shown that this remarkable phenomenon can be generated, manipulated and measured entirely on a tiny silica chip. They have also used the same chip to measure mixture—an often unwanted effect from the environment, but...