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

2026-07-22

Studies of homogeneous quantum gases, trapped in uniform optical-box potentials, bridge the fields of ultracold atoms and condensed matter physics. Being versatile and well-isolated systems, ultracold atoms offer an outstanding platform for engineering quantum many-body systems. Due to the variety of high precision measurement techniques from atomic physics, they can be used as analogue quantum simulators for addressing open questions in the physics of strongly correlated systems. This proposal suggests using ultracold bosons with tuneable interactions and trapped in uniform box potentials to experimentally study the critical behaviour of a Bose gas near its condensation temperature Tc. The project focuses on problems in beyond-mean-field physics that cannot be effectively tackled using the traditionally studied harmonically trapped gas. One key objective is the first measurement of the long-debated non-perturbative Tc shift due to interactions, which is a sensitive probe of the critical behaviour happening on all length scales. In addition, the project addresses critical scalings near Tc, which will be investigated through equilibrium and non-equilibrium measurements. In particular, experimental access to the critical slowing down of equilibration near Tc should allow a direct measurement of the dynamical critical exponent z, which is not possible with liquid helium. The proposed experiments will cover the full range of interaction strengths from non-interacting atoms to the largely unexplored unitary regime, where the interactions are as strong as allowed by quantum mechanics. This will also allow a study of the effect of the interaction strength on the size of the critical region and on the robustness of the universal critical behaviour. This proposal stands at the forefront of the field of quantum simulation and its results should have an impact beyond the atomic physics and quantum optics communities, strongly reinforcing European excellence in physics.

United Kingdom (UK)

2026-02-01