A quantum metasurface to control multiple properties of light

Controlling both the spatiotemporal and quantum properties of transmitted and reflected light.


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Scientists at Harvard University have devised a new type of metasurface that can control both the spatiotemporal and quantum properties of transmitted and reflected light.

Rivka Bekenstein, the lead author of the recent paper, said, “Quantum metasurfaces are an entirely new type of materials designed atom by atom, which enable applications such as quantum computation with photons.”

“We combined a state-of-the-art technique for manipulating the state of many atoms by long-range interactions (i.e., Rydberg interactions) with a recent discovery of how a single sheet of atoms can reflect light. We identified an architecture that can be realized in the laboratory, in which a single layer of atoms can act as a switchable quantum mirror.”

For this study, scientists reviewed different quantum metasurfaces that can be controlled to have different light scattering properties.

One of the most noticeable sources for the development of quantum technologies is entangled states, which are individual states that only exist for quantum entities. The quantum metamaterial proposed by the scientists empowers the production of specific entangled states of many light particles (i.e., photons), which are particularly important for quantum information processing applications.

In certain environmental conditions, atoms can be controlled to become direct using external electrical fields. Continuous examinations have moreover indicated that a single sheet of atoms can reflect light, resembling a regular mirror.

By utilizing Rydberg interactions that generally occur in atomic systems, scientists were able to distinguish a scheme where a single layer of atoms simultaneously reflects and transmits light in a quantum superposition. In other words, the subsequent quantum metasurface could both become transparent and reflect light, similar to a mirror.

Bekenstein said, “Our quantum metasurface is a new type of material that can make light co-exist in two different directions. This is done by manipulating the atoms’ state and then shining a weak laser to scatter from them.”

The design strategy employed by Bekenstein and her colleagues initiates quantum entanglement between various metasurfaces and light, just as between single light particles. Remarkably, the architecture they proposed could likewise be controlled to have shifting measures of photons in entrapped states, which is a significant ability for most quantum applications, including quantum computing.

Through a series of quantitative calculations, scientists analyzed how their metasurface enables quantum operations between atoms and photons, allowing for the generation of highly entangled photonic states that are ideal for quantum information processing applications.

Bekenstein said, “A key advantage of our architecture is that only one atom has to be prepared in a quantum superposition state in the laboratory. Hundreds of atoms construct the quantum metasurface, but only one has to be manipulated on the quantum mechanical level, which makes this proposal practical. This is enabled due to the long-range interaction we utilize in the scheme, which naturally exists for atoms in specific energy levels.”

Scientists introduced a technique to gain quantum control over the response of macroscopic materials to light. This technique could pave the way for the development of an entirely new type of quantum materials, while also potentially revolutionizing the current understanding of quantum optical materials and their response to light.

Bekenstein said, “We are currently exploring new experimental systems that can realize the quantum metasurfaces we proposed. We are also interested in revealing the nonlinear response of these quantum metasurfaces to light, which occur for higher intensity light beams. Finally, we are investigating specific practical applications of the proposed quantum metasurfaces for quantum information processing.”

Journal Reference:
  1. Quantum metasurfaces with atom arrays. DOI: 10.1038/s41567-020-0845-5


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