Chemical bonding via vacuum-assisted process

In a groundbreaking development, a team led by Professor Vahid Sandoghar at the Max Planck Institute for the Physics of Light (MPL) has succeeded in optically binding multiple molecules at greater distances using an optical resonator. This work marks the first time two molecules far apart have been excited simultaneously through a two-photon excitation.

The research group, known as "Quantum Optics and Quantum Photonics" under the leadership of Professor Sandoghar, has been working tirelessly to pave the way for the development of novel states in which material particles, such as molecules, can be 'stuck together' with light.

The team's latest achievement involves coupling spatially separated molecules via a modified vacuum field in an optical microresonator. Inside this plano-concave microresonator, light can be stored for a longer period, enabling the interaction of molecules and their hybridization with the resonator mode.

The experimental setup creates synthetic states of coupled molecules. The scientists insert an anthracene microcrystal doped with special dye molecules into the resonator. Each photon alone has no effect, but they can activate both molecules simultaneously when combined.

At distances of a few nanometers, the interaction between molecules is weakened to the point where they can no longer communicate with each other. However, the modified vacuum field in the microresonator strengthens this interaction, allowing the molecules to be excited simultaneously.

This process is not without its challenges. Quantum states are usually very fragile, making it challenging to couple several molecules together. Nevertheless, Sandoghar states that neither the molecules nor the photons can act alone in this process, but they must work in harmony to succeed.

The study of a precisely defined number of interacting emitters is an important building block for the processing of quantum information and is of great interest in quantum technology. Using high-resolution laser spectroscopy, the team investigates the interaction of the molecules and their hybridization with the resonator mode.

The appearance of new features in the resulting spectrum indicates changes in the molecular energy states, such as sub- and super-radiant modes. These changes suggest that the molecules are no longer completely independent due to their hybridization, which allows them to be excited simultaneously.

This work paves the way for the development of new hybrid light-matter states, opening up exciting possibilities for the future of quantum technology. The research promises to provide a deeper understanding of the interaction between light and matter, potentially leading to advancements in fields such as quantum computing and quantum communication.