Speaker
Description
Efimov states were theoretically predicted for the first time in 1970. They appear in a bosonic three-body system with zero total orbital angular momentum when at least two of the two-body subsystems have an s-wave state at zero energy. In this situation, an infinite number of three-body bound states is formed as a consequence of the appearance of an effective potential proportional to $-1/\rho^2$, where $\rho$ is the hyperradius. At the unitary limit, the ratio between the binding energies of two consecutive Efimov states is given by the scaling factor $e^{2\pi/s_0}$, where $s_0$ is the Efimov scaling exponent, which depends on the particle masses and the spatial dimension. Experimentally, Efimov states were observed only in 2006 in ultracold atomic gases, mainly due to the possibility of tuning the two-body interactions and approaching the zero-energy limit. In addition to the freedom to tune the interatomic interactions, ultracold traps also allow the geometry of the atomic cloud to be changed, transforming it from a three-dimensional (3D) to a two-dimensional (2D) environment. As Efimov states exist in 3D but not in 2D, it is possible to follow the evolution of the bound states by continuously changing the effective spatial dimension (D) of the system. In this talk, I will give an overview of the Brazilian group's results on the behaviour of universal observables under a continuous change of the spatial dimension.