Quantum optics: An entangled walk of photons

Although quantum effects such as entanglement and superposition are counterintuitive and often described as ‘spooky’, they are being observed and characterized in laboratories worldwide. The authors describe how they have designed and built an optical network, integrated in a glass chip, manipulates photons to simulate a process known as a discrete-time quantum walk. Furthermore, using a particular kind of entanglement, the authors simulated different classes of fundamental particles undergoing the quantum-walk process. The results are a step towards the development of quantum-mechanical machines that promise to outperform conventional supercomputers, which operate according to the laws of classical physics. Developments in quantum simulation are still at the stage of mimicking systems simple enough to be handled with classical computers. However, photonics is an attractive candidate for reaching the point at which quantum machines could outperform state-of-the-art supercomputers for particular tasks. This is partly thank