Communication technologies could soon deploy structured light to transport information faster and make data more secure, according to a new scientific review.
"What we really want is to do quantum mechanics with patterns of light," Andrew Forbes, physicist at the University of the Witwatersrand in South Africa, said in a news release. "By this, we mean that light comes in a variety of patterns that can be made unique -- like our faces."
Forbes is the first of author of a paper -- published Tuesday in the journal AVS Quantum Science -- detailing the technological progress being made in the field of structured light.
Light can be structured to produce different images or patterns. Because each light pattern is distinguishable from the others, structured light can be used like an alphabet.
"The cool thing is that there are, in principle at least, an infinite set of patterns, so an infinite alphabet is available," Forbes said.
Most quantum systems use polarization to distinguish light photons. Polarization only offers two values, limiting the amount of information that can be embedded in each photon. Using a patterned light alphabet allows for information to be carried at greater densities, according to the new research paper.
"Patterns of light are a route to what we term high-dimensional states," Forbes said. "They're high dimensional, because many patterns are involved in the quantum process. Unfortunately, the toolkit to manage these patterns is still underdeveloped and requires a lot of work."
Despite the potential of encoding alphabets based on patterns of light, "progress in harnessing high dimensional spatial mode entanglement remains in its infancy," according to the newly published review.
Still, researchers are making advances. For example, scientists have demonstrated entanglement swapping using spatial modes of light, quantum states confined to spatially separated waveguides. Scientists have also improved the resolution of ghost imaging, allowing them to more precisely measure entangled photons. But hurdles remain.
"We know how to create and detect photons entangled in patterns," said Forbes. "But we don't really have good control on getting them from one point to another, because they distort in the atmosphere and in optical fiber. And we don't really know how to efficiently extract information from them. It requires too many measurements at the moment."
Forbes and his colleagues suggest further advances can be made using simpler tools to yield more complex quantum states. According to the paper, physicists can move beyond the strictures of two dimensions by combining the advantages of polarization and patterns to produce hybrid light states.
"Rather than two dimensions of patterns, hybrid states allow access to multidimensional states, for example, an infinite set of two-dimensional systems," Forbes said. "This looks like a promising way forward to truly realize a quantum network based on patterns of light."
