Systems of Imprimitivity for the Clifford group (pp0339-0360)
          D.M. Appleby, Ingemar Bengtsson, Stephen Brierley, Asa Ericsson, Markus Grassl, and Jan-Ake Larsson
          doi: https://doi.org/10.26421/QIC14.3-4-9
Abstracts: It is known that if the dimension is a perfect square the Clifford group can be represented by monomial matrices. Another way of expressing this result is to say that when the dimension is a perfect square the standard representation of the Clifford group has a system of imprimitivity consisting of one dimensional subspaces. We generalize this result to the case of an arbitrary dimension. Let k be the square-free part of the dimension. Then we show that the standard representation of the Clifford group has a system of imprimitivity consisting of k-dimensional subspaces. To illustrate the use of this result we apply it to the calculation of SIC-POVMs (symmetric informationally complete positive operator valued measures), constructing exact solutions in dimensions 8 (handcalculation) as well as 12 and 28 (machine-calculation).
Key words: Clifford group, SIC POVM, Sparse representation