Scientists at the Ecole Polytechnique de lausanne (EPFL) made photons interact with pairs of atoms for the first time. This breakthrough is important for the field of quantum electrodynamics of resonators (QED), an advanced field that underlies quantum technology.
Humanity is moving towards the widespread use of technologies based on quantum physics. But in order to achieve this, you first need to master how to make light interact with matter – or, more accurately, photons with atoms. To some extent, such technologies are responsible for the advanced field of quantum electrodynamics of the resonator (QED). It is now being used in quantum networks and quantum information processing. But there is still a long way to go. Modern interactions of light and matter are limited to individual atoms, which limits a person’s ability to study them in the form of complex systems involved in quantum technologies.
In the new work, the researchers used Fermi gas (or the ideal Fermi – Dirac gas). It is a gas consisting of particles that satisfy the Fermi – Dirac statistics, that is, they have a low mass and a high concentration. For example, electrons in a metal. “In the absence of photons, gas can be produced in a state where atoms interact with each other to form loosely coupled pairs,” explains Jean-Philippe Brantou of the EPFL School of Basic Sciences. “When light hits a gas, some of these vapors are converted into chemically bound molecules, absorbed by photons.”
The key concept of the new effect is that it occurs “coherently”. This means that a photon is absorbed to turn a couple of atoms into a molecule, then emitted back and so on several times. “This means that the para-photon system forms a new type of particle state, which we called“ paired polariton-polariton ”- explains the scientist. “This became possible in a system where photons are confined in one place, where they have to strongly interact with atoms.”
Hybrid paired polaritons acquire some of the properties of photons. This means that they can be measured by optical methods. They also acquire some of the properties of a Fermi gas, the scientists conclude.
“Some of the very complex properties of a gas are converted into optical properties that can be measured directly, even without breaking the system. In the future, the technology will come in handy in quantum chemistry: scientists have demonstrated for the first time how certain chemical reactions can be coherently produced using single photons.