Normal charge densities in quantum critical superfluids

Understand

The normal density of a translation-invariant superfluid often vanishes at zero temperature, as is observed in superfluid Helium and conventional superconductors described by BCS theory.

• Here we show that this need not be the case.
• We investigate the normal density in models of quantum critical superfluids using gauge-gravity duality.
• Models with an emergent infrared Lorentz symmetry lead to a vanishing normal density.