  The interface of a cholesteric liquid crystal with an isotropic fluid can
display a range of unusual properties, such as a layer of topological defects
close to an undulated interface. These properties have been know for a long
time and have been explored for technological applications as a tunable
substrate for colloidal self-assembly. However, from a fundamental point of
view, this interface remains poorly understood and even basic properties, such
as the dependence of the surface tension on the attributes of the liquid
crystal, remain unknown. Here, we present a systematic calculation of the
structure and surface tension of the cholesteric-isotropic interface and how
these vary with the properties of the liquid crystal. We also suggest the
intriguing possibility of wetting of this interface by a blue phase.
