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).
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