Nav: Home

In a new quantum simulator, light behaves like a magnet

March 21, 2019

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."

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.

"We are theorists," says Savona. "We came up with the idea for this particular quantum simulator and modelled its behavior using traditional computer simulations, which can be done when the quantum simulator addresses a small enough system. Our findings prove that the quantum simulator we propose is viable, and we are now in talks with experimental groups who would like to actually build and use it."

Understandably, Rota is excited: "Our simulator can be applied to a broad class of quantum systems, allowing physicists to study several complex quantum phenomena. It is a truly remarkable advance in the development of quantum technologies."
-end-
Other contributors

Université Paris Diderot (France)

Reference

Riccardo Rota, Fabrizio Minganti, Cristiano Ciuti, Vincenzo Savona. Quantum critical regime in a quadratically-driven nonlinear photonic lattice. Physical Review Letters 122, 110405 (21 March 2019). DOI: 10.1103/PhysRevLett.122.110405

Ecole Polytechnique Fédérale de Lausanne

Related Quantum Mechanics Articles:

Bridge between quantum mechanics and general relativity still possible
An international team of researchers developed a unified framework that would account for this apparent break down between classical and quantum physics, and they put it to the test using a quantum satellite called Micius.
'Poor man's qubit' can solve quantum problems without going quantum
Researchers have built and demonstrated the first hardware for a probabilistic computer, a possible way to bridge the gap between classical and quantum computing.
Cracking a decades-old test, researchers bolster case for quantum mechanics
At upcoming FiO + LS conference, researchers will discuss creative tactics to get rid of loopholes that have long confounded tests of quantum mechanics.
Quantum computers to clarify the connection between the quantum and classical worlds
Los Alamos National Laboratory scientists have developed a new quantum computing algorithm that offers a clearer understanding of the quantum-to-classical transition, which could help model systems on the cusp of quantum and classical worlds, such as biological proteins, and also resolve questions about how quantum mechanics applies to large-scale objects.
Imaging of exotic quantum particles as building blocks for quantum computing
Researchers have imaged an exotic quantum particle -- called a Majorana fermion -- that can be used as a building block for future qubits and eventually the realization of quantum computers.
More Quantum Mechanics News and Quantum Mechanics Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...