Scientists at Sandia National Laboratories and the Max Planck Institute have developed a way to produce a web of quantum entangled photons using a far more simple setup than usual. The key is a precisely patterned surface 100 times thinner than paper, which could replace a roomful of optical equipment.
Quantum entanglement is the bizarre-sounding phenomenon where two particles can become so entwined together that manipulating one will instantly affect its partner, no matter how far apart they may be. This forms the basis for emerging technologies like quantum computing and quantum encryption.
The problem is, generating entangled groups of photons can be tricky, and is usually done with large arrays of lasers, specialized crystals, and other optical equipment. But the Sandia and Max Planck team has a much simpler setup – a metasurface.
These devices act kind of like lenses, manipulating light that passes through in a very controlled way. But rather than doing so using their curve and thickness, metasurfaces have been precisely etched with nanoscale structures to change the light according to the task at hand, including trapping atoms, capturing clearer colors in images, and even producing holograms. Best of all, metasurfaces can pull off these feats in much smaller devices than previous tech.
For this study, the team’s metasurface took the form of an ultrathin sheet of glass covered in nanostructures made of the semiconductor material gallium arsenide. When a laser is beamed through the metasurface, some of the photons that come out the other side do so in entangled pairs. And not just one pair at a time, but a whole web of entangled photons. This, the team says, normally takes a whole lab full of equipment to accomplish.
“It is quite complicated and kind of intractable when this multi-entanglement needs more than two or three pairs,” said Igal Brener, lead researcher on the study. “These nonlinear metasurfaces essentially achieve this task in one sample when before it would have required incredibly complex optical setups.”
Being able to induce quantum entanglement in groups of photons at once could have a wide range of applications for quantum computers, encryption, communication and optics. Before that happens though, the team says there's still more work to be done in improving the efficiency of the metasurface.
The research was published in the journal Science.
Source: Sandia Labs
