Q&A: New method confines light inside an organic material to form a hybrid quantum state

An international team of scientists led by the University of Ottawa has gone back to the kitchen cupboard to create a recipe that combines organic material and light to create quantum states.

Professor Jean-Michel Ménard, leader of the ultrafast Terahertz spectroscopy group at the Faculty of Science, coordinated with Dr. Claudiu Genes at the Max Planck Institute for the Science of Light (Germany) and with Iridian Spectral Technologies (Ottawa) to design equipment that can efficiently modify the properties of materials using quantum overlap with light.

The team designed a two-dimensional planar resonator – known as a metasurface – that captured the light. Using a sputter coating technique, they then deposited a thin layer of glucose on that metasurface to induce a strong interaction between the light molecules and the glucose in the sugar.

Their concept brings researchers closer to the technological ability to capture some of the unique properties of quantum systems that fall into a hybrid state of light and matter.

Faculty of Science Professors Ksenia Dolgaleva and Robert Boyd contributed to the work alongside Professor Menard, the lead author, who discusses the findings published in Nature Communications.

What did you decide to do and what did you find?

We present an innovative and efficient technique for synthesizing quantum organic materials by combining light and matter. When light in the far infrared region – at terahertz (THz) frequencies – is coupled to an organic material, it can couple to molecules, resulting in a quantum state that exhibits unique properties that are of increasing interest due to application their potential in modifying the physical and chemical properties of matter. These intriguing states arise only under specific conditions.

Our team identified these critical conditions and created a photonic trap, or device, to effectively confine light within a small volume space for a significant amount of time. This trap enables the establishment of a strong coupling regime between light and a molecular array.

Unlike previous approaches that relied on optical cavities made from two facing mirrors, we instead designed and tested a two-dimensional planar resonator known as a metasurface. This metasurface effectively allows optical confinement within a planar geometry, opening new practical avenues to explore the quantum regime of strong light-matter interactions.

Finally, we combined metasurfaces with traditional cavity geometries to form hybrid cavity architectures and observe an increase in the coupling strength between light and matter. These results are demonstrated with glucose, an organic compound with useful properties for the fields of biology and medicine.

Why use THz light and sugar?

Terahertz light is particularly interesting because it can cause vibrations in many molecules, including glucose molecules in the sugar. The vibrational energy of molecules is closely related to their properties, including their ability to engage in chemical reactions with other molecules.

Therefore, by designing platforms that enable strong coupling between terahertz light and the vibrations of molecules, which are the fundamental building blocks of organic substances, we have the potential to alter their properties to potentially gain control over the mechanisms at the foundation of life.

What did you ultimately find through your research?

We discovered efficient approaches to terahertz pair light and matter. The most promising concept is based on a structured metal surface, the metasurface, incorporated into the design of a photonic cavity. As a result, the light is doubly blocked and remains tightly sealed inside the device.

Our powerful plug-and-play platform allows potentially many organic materials to be incorporated into this device to create quantum systems with novel properties. This is due to the fact that a precise alignment of the device is not required to capture the light as this critical condition is mainly met by the geometry of the metal pattern of the metasurfaces. Interestingly, since scalable fabrication techniques exist to fabricate metasurfaces that interact with terahertz light, we believe that these devices can be used relatively quickly for real-life applications of quantum-enhanced chemical reactions.

What kind of impact could this research have?

These results bring us closer to the technological ability to harvest some of the unique properties of quantum systems that consist of a hybridized state of light and matter.

By conducting a systematic theoretical and experimental study of different types of photonic resonators, we discovered several new models of photonic resonators that can create a quantum overlap between a molecular material, glucose, and light in a specific region of the far-infrared spectral window. red called the terahertz region.

Previous work showed that this hybridization process, when involving terahertz light, modifies the original physical and chemical properties of the material. For example, the presence of a photonic resonator can change the rate of some chemical reactions involving that material.

In the future, we believe that this approach may help to regulate several molecular processes, leading to the application in medicine for rapid diagnosis and potentially new therapeutic strategies.