Galois-qudit stabilizer code[1,2] 

An \(((n,K,d))_q\) Galois-qudit code whose logical subspace is the joint eigenspace of commuting Galois-qudit Pauli operators forming the code's stabilizer group \(\mathsf{S}\). Traditionally, the logical subspace is the joint \(+1\) eigenspace, and the stabilizer group does not contain \(e^{i \phi} I\) for any \(\phi \neq 0\). The distance \(d\) is the minimum weight of a Galois-qudit Pauli string that implements a nontrivial logical operation in the code.

A Galois-qudit stabilizer code encoding an integer number of qudits (\(K=q^k\)) is denoted as \([[n,k]]_q\) or \([[n,k,d]]_q\). This notation differentiates between Galois-qudit and modular-qudit \([[n,k,d]]_{\mathbb{Z}_q}\) stabilizer codes, although the same notation is usually used for both. Galois-qudit stabilizer codes need not encode an integer number of qudits, with \(K=q^{n-\frac{r}{m}}\), where \(r\) is the number of generators of the stabilizer group, and \(q=p^m\) given prime \(p\) for all Galois qudits. As a result, \([[n,k,d]]\) notation is often used with non-integer \(k=\log_q K\).

A pair of Galois-qudit stabilizers on \(n\) Galois qudits with symplectic representation vectors \((a|b)\) and \((a^{\prime}|b^{\prime})\) commute iff their trace symplectic inner product is zero, \begin{align} \text{tr}(a \cdot b^{\prime} - a^{\prime}\cdot b) = \sum_{j=1}^{n} \text{tr}(a_j b^{\prime}_j - a^{\prime}_i b_i) = 0~. \tag*{(1)}\end{align} Symplectic representations of stabilizer group elements form a trace-symplectic self-orthogonal linear code over \(GF(q)^{2n}\). The trace-symplectic inner product reduces to the symplectic inner product when the field trace is removed, and a symplectic self-orthogonal set of vectors is automatically trace-symplectic self-orthogonal.

Another correspondence between Galos-qudit Pauli matrices and elements of the Galois field \(GF(q^2)\) yields the one-to-one correspondence between Galois-qudit stabilizer codes and trace-alternating self-orthogonal additive codes over \(GF(q^2)\) [2].

The sets of \(GF(q^2)\)-represented vectors for all generators yield a trace-alternating self-orthogonal additive code over \(GF(q^2)\).

Galois-qudit stabilizer codes can equivalently [3] (see also [4,5]) be defined using graphs, yielding an analytical form for the codewords [6].