  We construct the first example of a superstratum: a class of smooth
horizonless supergravity solutions that are parameterized by arbitrary
continuous functions of (at least) two variables and have the same charges as
the supersymmetric D1-D5-P black hole. We work in Type IIB string theory on T^4
or K3 and our solutions involve a subset of fields that can be described by a
six-dimensional supergravity with two tensor multiplets. The solutions can thus
be constructed using a linear structure, and we give an explicit recipe to
start from a superposition of modes specified by an arbitrary function of two
variables and impose regularity to obtain the full horizonless solutions in
closed form. We also give the precise CFT description of these solutions and
show that they are not dual to descendants of chiral primaries. They are thus
much more general than all the known solutions whose CFT dual is precisely
understood. Hence our construction represents a substantial step toward the
ultimate goal of constructing the fully generic superstratum that can account
for a finite fraction of the entropy of the three-charge black hole in the
regime of parameters where the classical black hole solution exists.

High Energy Physics - Theory;General Relativity and Quantum Cosmology