  We introduce a new operator representing the three-dimensional scalar
curvature in loop quantum gravity. The operator is constructed by writing the
Ricci scalar classically as a function of the Ashtekar variables and
regularizing the resulting expression on a cubical spin network graph. While
our construction does not apply to the entire Hilbert space of loop quantum
gravity, the proposed operator can be applied to concrete calculations in
various approaches which are derived from the framework of full loop quantum
gravity using states defined on cubical graphs.
