On the construction of equiangular frames from graphs
We give details of the 1--1 correspondence between equiangular frames
of n vectors for R^d and graphs with n vertices.
This has been studied recently for tight equiangular frames
because of applications to signal processing and quantum information theory.
The nontight examples given here (which correspond to graphs with
more than 2 eigenvalues) have the potential for similar
applications, e.g., the frame corresponding to the 5-cycle graph is
the unique Grassmannian frame of 5 vectors in R^3.
Further, the associated canonical tight frames have
a small number of angles in many cases.
mutually unbiased basis,
two angle frame,
algebraic graph theory,
Math Review Classification:
Primary 42C15, 05C50;
Secondary 05C90, 52B15
Length: 17 pages
Last Updated: 22 January 2009