Daniel Pérez Cruz


Jun 22, 2023 from 12:00 PM to 01:00 PM (Europe/Madrid / UTC200)


UPC campus nord, B4-212 (aula seminari)

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Daniel Pérez Cruz
 “Superfluid fraction in disordered quantum fluids”


An ultracold dilute gas of bosons can have a fraction of its components in the so-called superfluid state. A superfluid exhibits a series of counter-intuitive properties that are closely related to those of superconductors. As examples we can mention the non-classical rotational moment of inertia, the quantization of vorticity, and the capacity to flow without losses. Determining the superfluid fraction in an actual experiment with ultracold atoms is a non-trivial task. In a series of papers, A. Leggett derived strict upper and lower bounds for this quantity in terms of the local density of particles. Here we study numerically the superfluid fraction of a gas in both optical lattices and disordered (speckle) potentials in one and two spatial dimensions, directly comparing our numerical results to the aforementioned bounds.