QECC [[20,4,6]]

This pure code is based on a linear self-orthogonal code over GF(4) with generator matrix:

[1 0 0 0 0 0 0 0 1 a^2 0 1 0 a a^2 a 0 a^2 1 a]
[0 1 0 0 0 0 0 0 a^2 a^2 a a^2 1 1 0 a a a 0 0]
[0 0 1 0 0 0 0 0 a^2 1 0 1 a^2 0 a^2 1 a 0 1 1]
[0 0 0 1 0 0 0 0 1 0 1 1 1 1 a^2 1 1 1 1 a^2]
[0 0 0 0 1 0 0 0 0 1 a^2 1 1 1 1 a^2 1 1 1 1]
[0 0 0 0 0 1 0 0 1 a^2 1 a 1 a^2 a a^2 a^2 a 0 a^2]
[0 0 0 0 0 0 1 0 a^2 a^2 a^2 a a 0 1 a^2 a^2 1 1 1]
[0 0 0 0 0 0 0 1 a^2 1 1 0 a a^2 a 0 a^2 1 a 0]

QECC [[20,4,6]]

Matrix with stabilizers/seed generators and circuit for encoding: