CriticalBoseBox · Critical behaviour of Bose gases with tuneable interactions in uniform box traps

Critical behaviour of Bose gases with tuneable interactions in uniform box traps

The theory of quantum mechanics is fundamental for the description of the microscopic. Its understanding is vital for the details of chemical reactions, the development of novel materials, the accuracy of atomic clocks and the upcoming technological quantum revolution. But even after almost a century of research, many questions remain open, especially about the quantum mechanical behaviour of many interacting particles. For example, how exactly does a gas of classical colliding atoms turn into a quantum gas dominated by wave behaviour? In this project, we experimentally study this question with one of the most simple and best-controlled materials: A quantum gas; which is a gas of atoms less than a millionth of a degree above absolute zero, which is trapped in ultra-high vacuum by laser beams (see Figure). These artificial gases show almost unperturbed quantum behaviour and are thus an ideal platform to both study fundamental questions about quantum mechanics and to test potential quantum technologies. More precisely, we use ultracold potassium-39 atoms with tuneable interactions in a box trap to investigate the effect of interactions on the phase transition from a classical gas to a Bose-Einstein condensate; a phase, where a hundred thousand atoms form a macroscopic quantum wave. Of particular interest is the dynamical behaviour of our gas. In all ordinary materials, the microscopic processes (collisions between atoms) are much fast than macroscopic processes (e.g. sound waves, temperature changes). Thus, these systems are always close to an equilibrium. In dilute quantum gases, the situation is typically reversed because collisions are rare. But in our homogeneous trap, we can change the collision rate almost arbitrarily and thus connect both limits. Due to our geometry, we avoid loss processes that plague comparable experiments. This allows, on the one hand, to study the unexplored interplay of classical and quantum sound waves and, on the other hand, to generate exotic far-from-equilibrium states of matter. The overall objective of this experimental project is to study dynamics in interacting quantum gases related to the phase transition from a classical to a quantum system. Quantitative results are to serve as confirmations of established theories or as benchmarks for novel theoretical descriptions.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз