A pulse of light causes the polariton to disappear

Matter exists in different forms, for example in solid or liquid form. But matter can also take very unexpected forms, such as when you let light and matter meet in a very limited space. It’s easy to isolate a few molecules of matter, but capturing the light requires special equipment, and tiny nano-antennas that work much like old-fashioned TV antennas pick up a TV signal, but on a much smaller scale.

Because we can produce large areas covered by these antennas and aim in principle at future large-scale practical applications of polarization chemistry, we are very intrigued by the rapid processes that occur when these new interactions occur on the antennas. This is important when we design useful and energy-efficient future systems that work with light and matter, says Professor Alexander Dmitriev, University of Gothenburg.

It reflects chemical reactions

When light is captured and isolated on an antenna, then enclosed with some organic molecules, strange new bodies appear, a mixture of light and matter: the “polaritons”. If these new molecules participate in a chemical reaction, the reaction is completely reversed. It could be going slower or faster, or the energy difference in the reaction means it might go in a direction it was never intended and form entirely new reaction products.

This fascinating field of chemistry, called “Polaritonic Chemistry,” is changing the way we look at what is possible with chemistry. Because polaritons are made up of part light and part matter, they can be studied with light itself as the information carrier during the interaction when forming a polariton.

Pump-probe experiments using femtosecond laser sources reveal dynamics not otherwise available to us. Such studies pave the way for the development of chemistry in the ultrafast field and promise many exciting applications, from energy harvesting to quantum computing, says Joel Kotrov, University of Konstanz, first author of the scientific paper.

Destroyed by pulses of light

An international team of researchers from Sweden, Italy, Germany and Luxembourg who are experts in different fields (nano, organic molecules, quantum theory and ultrafast optics), reveal what happens when very short light pulses hit the poles in very narrow spaces. It turns out that they are quickly destroyed and then the whole system is controlled by conventional electronic transitions in the molecules instead.

Strange phenomena, such as the emergence and collapse of these mixed states of matter and light, are expressions of the quantum mechanical nature underlying our world. They promise new technological applications in the long term and at the same time fascinating from a fundamental point of view, says Professor Stefano Corni, from the University of Padua, Italy.

This is very important knowledge when designing Polaritonic Interactions. Reflexes can be fast, and one might be tempted to use short pulses of light to study them. But the disappearance of the poles will have a major impact on the expected outcomes of these new interactions. This work provides a profound new understanding of the processes involved.

The important aspect of this work is that it examines an area that was thought to be well understood. It is always important to deepen our existing knowledge and improve our understanding. In addition to new polariton chemistry, this work is also useful in practice for research groups working with quantum chemical systems, aiming to control chemical matter and interactions on very short (femtosecond) and very small (nanometre) time scales, says Niccolò Macafferi of Umeå University. and the University of Luxembourg.

Read more about Niccolo McCaffrey’s research