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Odd-characteristic analogue of the F_{2^h}-to-binary bijection and geometry

Establish whether an analogue of the bijection between stabiliser codes over F_{2^h} and binary stabiliser codes exists for stabiliser codes over finite fields of odd characteristic, and characterize the corresponding geometric objects and equivalence-preserving operations. Address the challenges that arise from the potential nonexistence of trace-orthogonal bases in odd characteristic and from the currently unknown geometric correspondence, potentially by formulating the interpretation in terms of affine rather than projective points.

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Background

The paper proves a bijection between stabiliser codes over F_{2h} and binary stabiliser codes, enabling a geometric interpretation via quantum sets of symplectic polar spaces and facilitating new classification and nonexistence results. This relies on trace-orthogonal bases, which exist in even characteristic and preserve trace-symplectic inner products.

For finite fields of odd characteristic, analogous structural tools are lacking: trace-orthogonal bases do not necessarily exist, and the geometric objects corresponding to such stabiliser codes have not been established. The authors suggest that projective interpretations may need to be replaced by affine viewpoints to properly capture equivalence under Clifford conjugation in odd characteristic.

References

We solved [1, Research Problem 4] in the case when q is even. Can we do something similar for codes over finite fields of odd characteristic? There are two drawbacks. First, there does not always exist a trace-orthogonal basis in odd characteristic. Second, it has not been established what these codes correspond to geometrically. Multiplying a column with -1 does not affect the projective geometry, but it does not come from a conjugation with a Clifford operator. This suggests that, instead of looking at the projective points determined by the columns, we should rather look at them as affine points.

Stabiliser codes over fields of even order (2401.06618 - Ball et al., 12 Jan 2024) in Section 6 (Conclusion)