This project is in the field of experimental quantum many-body physics, which means that we study the collective behaviour of many identical particles that interact in some way (pushing or pulling each other), while obeying the laws of quantum mechanics.
In our work, we aim to uncover the general principles of many-body physics using ultracold atomic gases cooled to less than a millionth of a degree above absolute zero temperature. These are highly controllable model systems, in which, for example, the strength of inter-particle interactions can be tuned at will. In our novel "quantum gas in a box" setup the atoms are literally held in a tiny box, about the size of a human hair, made out of laser beams. Compared to the more traditional ultracold-atom experiments, in which the atomic clouds are held in parabolic (bowl-like) traps, this new system offers several advantages - it generally allows for easier comparisons of experiments with the theoretical models and in some cases it allows measurements that could not have been done at all with parabolic traps.
Generally, we understand pretty well quantum many-body behaviour if the particles interact only weakly with each other and if the system is in equilibrium, or close to it. However, things become highly non-trivial if the interactions are very strong, leading to a highly correlated behaviour of the particles. Moreover, even weakly interacting systems can be hard to understand if they are far from equilibrium, for example because of constant changes in the environmental conditions, such as due to external forces that constantly drive the system.
We are focusing on such non-trivial behaviour, and in particular on some of its most extreme examples. One such example is the case of the unitary Bose gas, in which the interactions are as strong as possible, that is, as strong as allowed by the laws of quantum mechanics. Another example is turbulence, where the external forces drive the system in such a way that its behaviour becomes chaotic and extremely hard to characterise from first principles.
Beyond its fundamental importance, better understanding of many-body quantum physics is also relevant for practical purposes. For example, better understanding of the underlying principles of strongly-correlated behaviour in the practically relevant materials, such as the high-temperature superconductors, could allow for controllable design of superior materials with tailor-made properties. Moreover, there is now a number of emerging quantum technologies, where the quantum mechanical behaviour is fundamental for superior performance. Any quantum device that actually does something useful will during its operation inevitably be out of equilibrium, so understanding the general principles of out-of equilibrium quantum behaviour is of paramount importance for these emerging technologies.
