Efficient Decoherence Control Algorithms

4 Clifford Codes

A fundamental problem is to decide when a Clifford codes is not equal to a stabilizer code. If we are given a Clifford code defined by (N,χ )  with nonabelian normal subgroup N  of E  , there might exist an abelian normal subgroup N0  of E  and a one-dimensional character of N0  so that the two codes are the same,

        ∑                    ∑
P = χ(1)    χ(n-1)ρ(n) = χ(1)    χ0(n-1)ρ(n) = P0.
    |N| n∈N             |N0 |n∈N0
In other words, the Clifford code might turn out to be a stabilizer code. The publications below give criteria that allow one to decide this question.