Physics

New Invention Triggers One of Quantum Mechanics’ Strangest and Most Useful Phenomena

Metasurface Entangled Photons

In this artist’s rendering of a metasurface, light passes through tiny, rectangular structures — the building blocks of the metasurface — and creates pairs of entangled photons at different wavelengths. The device was designed, fabricated, and tested through a partnership between Sandia National Laboratories and the Max Planck Institute for the Science of Light. Credit: Courtesy of Igal Brener, Sandia National Laboratories

Through the Quantum Looking Glass

By helping scientists control a strange but useful phenomenon of quantum mechanics, an ultrathin invention could make future computing, sensing, and encryption technologies remarkably smaller and more powerful. The device is described in new research that was recently published in the journal Science.

This device could replace a roomful of equipment to link photons in a bizarre quantum effect called entanglement, according to scientists at Sandia National Laboratories and the Max Planck Institute for the Science of Light. It is a kind of nano-engineered material called a metasurface and paves the way for entangling photons in complex ways that have not been possible with compact technologies.

When photons are said to be entangled, it means they are linked in such a way that actions on one affect the other, no matter where or how far apart the photons are in the universe. It is a spooky effect of quantum mechanics, the laws of physics that govern particles and other very tiny things.

Green laser light illuminates a metasurface that is a hundred times thinner than paper, which was fabricated at the Center for Integrated Nanotechnologies. CINT is jointly operated by Sandia and Los Alamos national laboratories for the Department of Energy Office of Science. Credit: Craig Fritz, Sandia National Laboratories

Although the phenomenon might seem bizarre, researchers have harnessed it to process information in new ways. For example, entanglement helps protect delicate quantum information and correct errors in quantum computing, a field that may someday have sweeping impacts on science, finance, and national security. Entanglement is also enabling advanced new encryption methods for secure communication.

Research for the groundbreaking device, which is a hundred times thinner than a sheet of paper, was conducted, in part, at the Center for Integrated Nanotechnologies, a Department of Energy Office of Science user facility operated by Sandia and Los Alamos national laboratories. Sandia’s team received funding from the Office of Science, Basic Energy Sciences program.

Light goes in, entangled photons come out

The new metasurface acts as a portal to this unusual quantum phenomenon. In some ways, it’s like the mirror in Lewis Carroll’s “Through the Looking-Glass,” through which the young protagonist Alice experiences a strange, new world.

Instead of walking through their new device, scientists shine a laser through it. The beam of light passes through an ultrathin sample of glass covered in nanoscale structures made of a common semiconductor material called gallium arsenide.

“It scrambles all the optical fields,” said Sandia senior scientist Igal Brener. He is an expert in a field called nonlinear optics and led the Sandia team. Occasionally, he said, a pair of entangled photons at different wavelengths emerge from the sample in the same direction as the incoming laser beam.

Sandia National Laboratories senior scientist Igal Brener, an expert in nonlinear optics, led a team that helped demonstrate a device that is paving the way for powerful, compact quantum information processing technologies. Credit: Craig Fritz, Sandia National Laboratories

Brener said he is enthusiastic about this device because it is designed to produce complex webs of entangled photons. Instead of just one pair at a time, it can produce several pairs all entangled together, and some that can be indistinguishable from each other. Some technologies require these complex varieties of so-called multi-entanglement for sophisticated information processing schemes.

Although other miniature technologies based on silicon photonics can also entangle photons, they lack the much-needed level of complex, multi-entanglement. Until now, the only way to produce such results was with multiple tables full of lasers, specialized crystals, and other optical equipment.

“It is quite complicated and kind of intractable when this multi-entanglement needs more than two or three pairs,” Brener said. “These nonlinear metasurfaces essentially achieve this task in one sample when before it would have required incredibly complex optical setups.”

The Science paper outlines how the team successfully tuned their metasurface to produce entangled photons with varying wavelengths. This was a critical precursor to generating several pairs of intricately entangled photons simultaneously.

However, the scientists note in their paper that the efficiency of their device — the rate at which they can generate groups of entangled photons — is lower than that of other techniques and will need to be improved.

What is a metasurface?

A metasurface is a synthetic material that interacts with light and other electromagnetic waves in ways conventional materials can’t. Brener said that commercial industries are busy developing metasurfaces because they take up less space and can do more with light than, for instance, a traditional lens.

“You now can replace lenses and thick optical elements with metasurfaces,” Brener said. “Those types of metasurfaces will revolutionize consumer products.”

Sandia is one of the leading institutions in the world performing research in metasurfaces and metamaterials. Between its Microsystems Engineering, Science and Applications complex, which manufactures compound semiconductors, and the nearby Center for Integrated Nanotechnologies, scientists have access to all the specialized tools they need to design, fabricate, and analyze these ambitious new materials.

“The work was challenging as it required precise nanofabrication technology to obtain the sharp, narrowband optical resonances that seed the quantum process of the work,” said Sylvain Gennaro, a former postdoctoral researcher at Sandia who worked on several aspects of the project.

The device was designed, fabricated, and tested through a partnership between Sandia and a research group led by physicist Maria Chekhova. She is an expert in the quantum entanglement of photons at the Max Planck Institute for the Science of Light.

“Metasurfaces are leading to a paradigm shift in quantum optics, combining ultrasmall sources of quantum light with far-reaching possibilities for quantum state engineering,” said Tomás Santiago-Cruz. He is a member of the Max Plank team and first author on the paper.

Brener, who has studied metamaterials for more than a decade, said this newest research could possibly spark a second revolution — one that sees these materials developed not just as a new kind of lens, but as a technology for quantum information processing and other new applications.

“There was one wave with metasurfaces that is already well established and on its way. Maybe there is a second wave of innovative applications coming,” he said.

Reference: “Resonant metasurfaces for generating complex quantum states” by Tomás Santiago-Cruz, Sylvain D. Gennaro, Oleg Mitrofanov, Sadhvikas Addamane, John Reno, Igal Brener and Maria V. Chekhova, 25 August 2022, Science.
DOI: 10.1126/science.abq8684

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  • 1. Topological vortex and anti-vortex field pairs generate or annihilate at the limit points, and encounter, split or merge at the bifurcation points of the 3-dimensional vector order parameter. They can form unstable point defects system.
    2. The most raw field and interaction in the universe can be written in terms of the topological vortex and anti-vortex field pairs.
    3. The gravitation that comes from the topological vortex and anti-vortex field pairs is the beginning of all things, and is the most raw power for maintaining and connecting the world.
    4. The unified field theory can be written in terms of the interaction for topological vortex and anti-vortex field pairs that is topological vortex and anti-vortex field = matter and anti-matter = monopole particles = graviton.
    Please see https://zhuanlan.zhihu.com/p/390071860.

  • "When photons are said to be entangled, it means they are linked in such a way that actions on one affect the other, no matter where or how far apart the photons are in the universe."

    No it doesn't mean that. Entanglement is a kind of "super-classical" correlation that can occur in algebraic (quantum) probability and there's no grounds for belief in "spooky action" - or "werewaves" - in it (you have to subscribe to an... eccentric interpretation of QM for that sort of thing). I think it'd be helpful if science journalists would consult a physicist who isn't appallingly "quantum foundations" illiterate (warning: most are) before writing about quantum mechanics.

  • Funny at a place named earth, silt slit silt. Photons how to create, cerns particle collision 💥💢💢💢🖤. A dark or very very 🌞 bright creation.comments above are well been in a classsroooom to long maybe😆🤣😂light positive negative and neutral 😐 ✨ 🙂 😊 fast quantum... Mechanics.....🤽‍♀️🚵‍♀️🛠⚒🔨🧰🧰🧰🧰🧲⚗🧬🧪🧫its somewhere beneficial for ???? Powers are for goodness...

  • >Paul Hayes
    >No it doesn’t mean that. Entanglement is a kind of “super-classical” >correlation

    all actual testing via Bell's Theorem says otherwise

    • Phil G, no it doesn't say otherwise. All the tests of Bell / CHSH inequalities have indeed confirmed that QM is correct and that such inequalities can be violated but I haven't said that QM is incorrect; I've said that it doesn't justify the "spooky action" *interpretation* of what's going on. In fact the best known full "interpretations" of QM that do justify and actually entail it (e.g. Bohmian mechanics) aren't really interpretations of QM at all. These "hidden variable" theories - a better name is "classical models of QM" - are really *alternatives* to QM; "completions" of it in the antique Bohr/Einstein lingo. The standard textbook, "Copenhagen", interpretation and modern "neo-Copenhagen" interpretations such as QBism and Rovelli's RI certainly do not entail or justify the "spooky action" interpretation of what those Bell inequality violations, GHZ results etc mean.

  • As a senior lay American male with my still technically unpublished theory of gravity, to me it all looks and sounds like a glorified version of the 'double-slit' experiments from which the misinterpretation of pulsing curved lines of gravity force causing photons, electrons and small molecules to take different paths, to appear as both particles and waves, led to the origin of the imaginative theory of 'quantum mechanics.'

  • I have long held a hypothesis that a quanta (or string) is actually a three dimensional standing wave of electromagnetic radiation bound by the energy of its own fields (someone in a physics forum once told me this was impossible because electromagnetic waves can only ever propagate linearly - which I think the slit experiments and the fact you can bend light with magnetism discredits).
    I'm curious about the entangled photons of different frequencies - is one photon actually a harmonic frequency of the other ? Not unlike a differently tuned string on a guitar vibrating in sympathetic harmony with another hosting a standing acoustic wave.

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Sandia National Laboratories

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