By Lancaster University February 12, 2025
Collected at: https://scitechdaily.com/physicists-unlock-a-new-way-to-bend-light-bringing-superlenses-and-cloaking-closer-to-reality/
Scientists have found a way to achieve negative refraction—where light bends the “wrong” way—using carefully arranged atomic arrays instead of engineered metamaterials.
This breakthrough has enormous implications, potentially leading to superlenses that see beyond microscopic limits and even cloaking devices.
Breaking the Rules of Light with Atomic Arrays
For the first time, scientists have achieved negative refraction using carefully arranged atomic arrays — without relying on artificially engineered metamaterials.
For years, researchers have sought new ways to manipulate light, often pushing the boundaries of what seemed physically possible. One of the most intriguing challenges in optics is negative refraction, where light bends in the opposite direction from its usual path. This phenomenon has the potential to revolutionize technology, leading to breakthroughs like superlenses that see beyond microscopic limits and cloaking devices that make objects invisible.
Now, scientists have taken a major step forward. By precisely arranging atoms into structured arrays, they have successfully demonstrated negative refraction — without the need for complex, manufactured metamaterials.
Revolutionizing Optics with Atomic Interactions
In a study published today (February 12) in Nature Communications, Professor Janne Ruostekoski and Dr. Kyle Ballantine from Lancaster University, along with Dr. Lewis Ruks from NTT Basic Research Laboratories in Japan, unveiled a new approach to controlling how atoms and light interact.
Natural materials interact with light through atomic transitions, where electrons jump between different energy levels. However, this interaction process has significant limitations. For instance, light primarily interacts with its electric field component, leaving the magnetic field component largely unused.
Metamaterials and Their Challenges
These inherent constraints in the optical properties of natural materials have driven the development of artificially engineered metamaterials which rely on the phenomenon of negative refraction.
Refraction occurs when light changes direction as it passes, e.g., from air into water or glass. Negative refraction, however, is a counterintuitive effect where light in a medium bends in the opposite direction to what is typically observed in nature, challenging conventional understanding of how light behaves in materials.
Superlenses and Cloaking: The Future of Negative Refraction
The allure of negative refraction lies in its groundbreaking potential applications, such as creating a perfect lens capable of focusing and imaging beyond the diffraction limit or developing cloaking devices that render objects invisible.
While negative refraction has been achieved in metamaterials, practical applications at optical frequencies remain hampered by fabrication imperfections and non-radiative losses, which still severely limit applications.
The novel approach by the Lancaster and NTT team involves performing detailed, atom-by-atom simulations of light propagating through atomic arrays.
Their work demonstrates that the cooperative response of atoms can enable negative refraction, eliminating the need for metamaterials altogether.
The Power of Collective Atomic Responses
Professor Janne Ruostekoski from Lancaster University said: “In such cases, atoms interact with one another via the light field, responding collectively rather than independently. This means the response of a single atom no longer provides a simple guide to the behavior of the entire ensemble. Instead, the collective interactions give rise to emergent optical properties, such as negative refraction, which cannot be predicted by examining individual atoms in isolation.”
These effects are made possible by trapping atoms in periodic optical lattices. Optical lattices are like “egg cartons” made of light, where atoms are held in place by standing light waves.
Dr. Lewis Ruks at NTT said: “These precisely arranged atomic crystals allow researchers to control the interactions between atoms and light with extraordinary precision, paving the way for novel technologies based on negative refraction.”
A Game-Changer for Optical Technology
The collective behavior of atoms in optical lattices offers several key advantages. Unlike artificially manufactured metamaterials, atomic systems provide a pristine, clean medium free from fabrication imperfections. In such systems, light interacts with atoms in a controlled and precise manner, without the absorption losses that typically convert light into heat.
These unique properties make atomic media a promising alternative to metamaterials for practical applications of negative refraction.
Reference: “Negative refraction of light in an atomic medium” by L. Ruks, K. E. Ballantine and J. Ruostekoski, 12 February 2025, Nature Communications.
DOI: 10.1038/s41467-025-56250-w
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