Physicists design an optical mirror made of a few hundred atoms.

Physicists at the Max Planck Institute for Quantum Optics (MPQ) have designed the lightest optical mirror imaginable. The new metamaterial is made of a single structured layer consisting of a few hundred identical atoms. Atoms are arranged in the two-dimensional matrix of an optical network made up of interfering laser beams. The research results are the first such experimental observations in a new emerging field of quantum optics below wavelength with ordered atoms. Until now, the mirror is the only one of its kind. The results are published today in Nature.

Mirrors generally use highly polished metal surfaces or specially coated optical glass to improve performance at smaller weights. But MPQ physicists now demonstrated for the first time that even a single structured layer of a few hundred atoms could already form an optical mirror, making it the lightest imaginable. The new mirror is only several tens of nanometers thick, which is a thousand times thinner than the width of a human hair. However, the reflection is so strong that it could even be perceived with the pure human eye.

The mechanism behind the mirror.

The mirror works with identical atoms arranged in a two-dimensional matrix. They are arranged in a regular pattern with a space less than the optical transition wavelength of the atom, typical and necessary characteristics of metamaterials. Metamaterials are artificially designed structures with very specific properties that are rarely found naturally. They obtain their properties not from the materials from which they are made, but from the specific structures with which they are designed. The characteristics (the regular pattern and the spacing of the lower wavelength) and their interaction are the two crucial works behind this new type of optical mirror. First, the regular pattern and spacing of atoms in the lower wavelength suppress diffuse light scattering, grouping the reflection into a constant, one-way beam of light. Second, due to the relatively close and discrete distance between the atoms, an incoming photon can bounce back and forth between the atoms more than once before it is reflected. Both effects, suppressed light scattering and photon bounce, lead to an “improved cooperative response to the external field”, which means in this case: very strong reflection.

Advances on the road to more efficient quantum devices

At a diameter of around seven microns, the mirror itself is so small that it is far beyond visual recognition. The apparatus on which the device is created, however, is huge. Fully stylish with other quantum optical experiments, it has over a thousand individual optical components and weighs around two tons. Therefore, the novel material would hardly affect the commodity mirrors that people use on a daily basis. The scientific influence on the other side can be powerful.

“The results are very exciting for us. As in typical bulk diluted sets, photon-mediated correlations between atoms, which play a vital role in our system, are generally neglected in traditional quantum optics theories. For On the other hand, the ordered series of atoms made by charging ultra-cold atoms in optical networks were exploited primarily to study quantum simulations of condensed matter models. But now it turns out to be a powerful platform to study new quantum optical phenomena as well, “Jun explains. Rui, Postdoc researcher and first author. of the paper

Further research throughout this story could deepen the fundamental understanding of quantum theories of the interaction of light matter, the physics of many bodies with optical photons, and enable the engineering of more efficient quantum devices.

“Many exciting new opportunities have opened up, such as an intriguing approach to studying quantum optomechanics, which is a growing field of study of the quantum nature of light with mechanical devices. Or, our work could also help create better quantum memories or even build an interchangeable quantum optical mirror, “adds David Wei, a doctoral researcher and second author. “They are both exciting advances in quantum information processing.”

Provided by the Max Planck Institute for Quantum Optics