I am very happy to share that our paper “Floquet engineering of Feshbach resonances in ultracold gases” has been published in Science Advances. 🎉
This project has been with me for quite a while. It started during my Master’s thesis, where I worked on the idea of controlling Feshbach resonances with strong radio-frequency magnetic fields. Back then, much of the work was still about understanding the theory and figuring out whether the required RF fields could realistically be produced in the lab.
Feshbach resonances are one of the key tools in ultracold atom experiments. They allow us to tune how strongly atoms interact with each other, usually by changing an external magnetic field. What we show in the paper is that this control can be extended by periodically modulating the magnetic field. In simple terms, the drive creates dressed molecular states, and whenever one of them crosses the atomic scattering threshold, a new resonance appears.
This means that the position of a resonance is no longer only fixed by the atomic species. Instead, we can move it by changing the parameters of the drive.
A major challenge is that driven systems can also heat, leading to atom loss. We therefore introduced a two-color drive, adding a second modulation frequency to reshape the loss profile. This allowed us to suppress losses while keeping the elastic interactions strong enough to observe collective dynamics of the gas.
