In these lectures I describe a theory of dark matter superfluidity developed in the last few years. The particles are axion-like, with masses order eV. They Bose-Einstein condense into superfluid phase central regions galaxy halos. phonon excitations turn couple to baryons and mediate long-range force (beyond Newtonian gravity). For suitable choice equation state, this reproduces various galact...

We have investigated the superfluid properties of a ring of weakly interacting and degenerate 1D Bose gas at thermal equilibrium with a rotating vessel. The conventional definition of superfluidity predicts that the gas has a significant superfluid fraction only in the Bose condensed regime. In the opposite regime, it is found that a superfluid behaviour can still be identified when the probabi...

I present here a microscopic theory for the superfluidity of 4 He (He II) derived from experiments, and answer its essential questions. With a " momenton " model, the superfluid is shown to feature as a " harmonic superfluid ". In which a new bonding type, the " superfluid bond " , is formed. Its activation causes the anomalous thermal excitation, the large excess of specific heat, etc. The sup...

We discuss superfluidity in neutron matter, with particular attention to induced interactions and to universal properties accessible with cold atoms.

We have investigated the superfluid properties of a ring of weakly interacting and degenerate 1D Bose gas at thermal equilibrium with a rotating vessel. The conventional definition of superfluidity predicts that the gas has a significant superfluid fraction only in the Bose condensed regime. In the opposite regime, it is found that a superfluid behaviour can still be identified when the probabi...

Superfluidity, the ability of a fluid to move without dissipation, is one of the most spectacular manifestations of the quantum nature of matter. We explore here the possibility of superfluid motion of light. Controlling the speed of a light packet with respect to a defect, we demonstrate the presence of superfluidity and, above a critical velocity, its breakdown through the onset of a dissipat...

The purpose of these notes is to give a brief review of superfluidity in neutron stars. After a short presentation explaining why and how superfluidity is expected in the crust and core of neutron stars, consequences on thermal evolution and rotational dynamics are discussed. The second part summarizes a formalism that has been recently developped to describe the hydrodynamics of superfluids or...