One example of a complex quantum system is that of magnets placed at really low temperatures. Close to absolute zero (-273.15 degrees Celsius), magnetic materials may undergo what is known as a quantum phase transition. Like a conventional phase transition (e.g. ice melting into water, or water evaporating into steam), the system still switches between two states, except that close to the transition point the system manifests quantum entanglement, the most profound feature predicted by quantum mechanics. Studying this phenomenon in real materials is an astoundingly challenging task for experimental physicists.
But physicists at EPFL have now come up with a quantum simulator that promises to solve the problem. The simulator is a simple photonic device that can easily be built and run with current experimental techniques. But more importantly, it can simulate the complex behavior of real, interacting magnets at very low temperatures. The simulator may be built using superconducting circuits, the same technological platform used in modern quantum computers. The circuits are coupled to laser fields in such a way that it causes an effective interaction among light particles (photons).