Light behaving like a magnet in a quantum simulator

When subject to the laws of quantum mechanics, systems made of many interacting particles can display behaviour so complex that its quantitative description defies the capabilities of the most powerful computers in the world. In 1981, the visionary physicist Richard Feynman argued we can simulate such complex behavior using an artificial apparatus governed by the very same quantum laws — what has come to be known as a “quantum simulator.”

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 led by Vincenzo Savona 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,” says Riccardo Rota, the postdoc at Savona’s lab who led the study. “But more importantly, it can simulate the complex behavior of real, interacting magnets at very low temperatures.”

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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). “When we studied the simulator, we found that the photons behaved in the same way as magnetic dipoles across 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 set up the experiment itself.

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Kepler Space Telescope’s first exoplanet candidate confirmed

Launched almost exactly 10 years ago, the Kepler Space Telescope has discovered thousands of exoplanets using the transit method — small dips in a star’s brightness as planets cross in front of the star. Because other phenomena can mimic transits, Kepler data reveal planet candidates, but further analysis is required to confirm them as genuine planets.

Kepler-1658 is 50% more massive and three times larger than the Sun. The newly confirmed planet orbits at a distance of only twice the star’s diameter, making it one of the closest-in planets around a more evolved star — one that resembles a future version of our Sun. Standing on the planet, the star would appear 60 times larger in diameter than the Sun as seen from Earth.

Planets orbiting evolved stars similar to Kepler-1658 are rare, and the reason for this absence is poorly understood. The extreme nature of the Kepler-1658 system allows astronomers to place new constraints on the complex physical interactions that can cause planets to spiral into their host stars. The insights gained from Kepler-1658b suggest that this process happens slower than previously thought, and therefore may not be the primary reason for the lack of planets around more evolved stars.

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“Kepler-1658 is a perfect example of why a better understanding of host stars of exoplanets is so important.” said Chontos. “It also tells us that there are many treasures left to be found in the Kepler data.”

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Kitbull

Kitbull, directed by Rosana Sullivan and produced by Kathryn Hendrickson, reveals an unlikely connection that sparks between two creatures: a fiercely independent stray kitten and a pit bull. Together, they experience friendship for the first time.

Director Rosana Sullivan and Producer Kathryn Hendrickson introduce their Pixar SparkShort, Kitbull.

Get a sneak peek at the making of Kitbull, a Pixar SparkShort, directed by Rosana Sullivan and produced by Kathryn Hendrickson.