In a new quantum simulator, light behaves like a magnet – ScienceDaily


Subject to the laws of quantum mechanics, systems made up of many interacting particles can display such complex behavior that their quantitative description defies the capabilities of the world's most powerful computers. In 1981, the visionary physicist Richard Feynman claimed that we could simulate such complex behavior with the aid of an artificial apparatus governed by the same quantum laws, what we now call a "quantum simulator". ".

An example of a complex quantum system is that of magnets placed at very low temperatures. Near absolute zero (-273.15 degrees Celsius), magnetic materials can undergo what is called a "quantum phase transition". Like a classical phase transition (for example, melting ice into water or evaporation of water into steam), the system switches between two states except that near the transition point, the system manifests a quantum entanglement – the deepest feature predicted by quantum mechanics. The study of this phenomenon in real materials is an extremely difficult task for experimental physicists.

But physicists led by Vincenzo Savona at EPFL have developed a quantum simulator that promises to solve the problem. "The simulator is a simple photonic device that can easily be built and operated with current experimental techniques," says Riccardo Rota, a postdoctoral scientist from the Savona laboratory who led the study. "But more importantly, it can simulate the complex behavior of real magnets interacting at very low temperatures."

The simulator can be built using superconducting circuits – the same technological platform used in modern quantum computers. The circuits are coupled to the laser fields so as to create an effective interaction between the light particles (photons). "When we studied the simulator, we found that photons behaved in the same way as magnetic dipoles through the quantum phase transition in real materials," says Rota. In short, we can now use photons to run a virtual experiment on quantum magnets instead of having to configure the experiment itself.

"We are theoreticians," says Savona. "We had the idea of ‚Äč‚Äčthis particular quantum simulator and modeled its behavior with the help of classical computer simulations, which can be done when the quantum simulator treats a sufficiently small system." Our results prove that the the quantum simulator we propose is viable, now in talks with experimental groups who really want to build it and use it. "

Naturally, Rota is excited: "Our simulator can be applied to a vast class of quantum systems, allowing physicists to study multiple complex quantum phenomena – a truly remarkable advance in the development of quantum technologies."

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Material provided by Federal Institute of Technology in Lausanne. Note: Content can be changed for style and length.


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