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Superradiance Solves Solar Storage

An international team of theoretical quantum physicists is working on a way of absorbing light and storing it as energy.

Dr Tom Stace of The University of Queensland said the research could revolutionise solar electricity generation and storage, and create a new generation of cameras and optical fibre-based communications. “In the dark or in bright light, a camera using this technology would see better than the human eye, and produce super-high resolution pixels,” he said.

The researchers are exploring a phenomenon known as “superradiance”, which occurs when atoms interact with the surrounding electromagnetic field, absorbing and emitting light at high speed. “Collectively, the atoms release a far more intense light pulse than they can individually,” Stace said.

He said the research addressed a fundamental scientific problem of how to optimise energy absorption before the atoms released it back as light. “The ability to harness light at an atomic level would improve solar panels, and bring scientists a step closer to building a ‘super-absorber’ for energy storage,” Stace said.

The researchers were intrigued by the process used by algae to transform light into electrochemical energy, but questioned conventional thinking about the ability of nano­structures to rapidly absorb energy, and how to prevent it being reemitted just as quickly.

“We began by asking how light absorption might be increased if an algae’s chloroplasts… could be re-engineered,” he said. “Our theoretical model shows that superabsorption – the reciprocal process of superradiance – can be achieved and sustained in certain simple nanostructures by engineering how the atoms interact with one another.

“By combining the well-established physical phenomena of superradiance, light filtering, photonic band gaps and quantum feedback control, we demonstrated that it is possible to sustain super-linear scaling of the light absorption rate.”

Writing in Nature Communications, the researchers have explained how interactions between atoms in a suitable geometrical arrangement might allow a quantum system to be controlled so that a sustained superabsorbing state can exist. The researchers have proposed a particular array of quantum dots with a molecular ring structure that is similar to the photosynthetic light-harvesting complex found in algae.

“Our design might become the basis of highly efficient systems for harnessing solar energy in the future,” Stace said. “But in the meantime, what we’ve discovered about super­radiance could help build an ultra-sensitive light sensor for the world’s most powerful camera.”