On Invariant Notions of Segre Varieties in Binary Projective Spaces

Abstract

Invariant notions of a class of Segre varieties $\Segrem(2)$ of PG(2^m - 1, 2) that are direct products of $m$ copies of PG(1, 2), $m$ being any positive integer, are established and studied. We first demonstrate that there exists a hyperbolic quadric that contains $\Segrem(2)$ and is invariant under its projective stabiliser group $\Stab{m}{2}$. By embedding PG(2^m - 1, 2) into \PG(2^m - 1, 4), a basis of the latter space is constructed that is invariant under $\Stab{m}{2}$ as well. Such a basis can be split into two subsets whose spans are either real or complex-conjugate subspaces according as $m$ is even or odd. In the latter case, these spans can, in addition, be viewed as indicator sets of a $\Stab{m}{2}$-invariant geometric spread of lines of PG(2^m - 1, 2). This spread is also related with a $\Stab{m}{2}$-invariant non-singular Hermitian variety. The case $m=3$ is examined in detail to illustrate the theory. Here, the lines of the invariant spread are found to fall into four distinct orbits under $\Stab{3}{2}$, while the points of PG(7, 2) form five orbits.

18 pages, 1 figure; v2 - version accepted in Designs, Codes and Cryptography

References in corpus (2)

• On polynomial invariants of several qubits
• Three fermions with six single particle states can be entangled in two inequivalent ways

Cited by in corpus (6)

• Aspects of the Segre variety S_{1,1,1}(2)
• A Notable Relation between $N$-Qubit and $2^{N-1}$-Qubit Pauli Groups via Binary $\mathrm{LGr}(N,2N)$
• Orbits of the stabiliser group of the Segre variety product of three projective lines
• Tetrads of lines spanning PG(7,2)
• Classification of subspaces in ${\mathbb{F}}^2\otimes {\mathbb{F}}^3$ and orbits in ${\mathbb{F}}^2\otimes {\mathbb{F}}^3\otimes {\mathbb{F}}^r$
• Finite Projective Spaces, Geometric Spreads of Lines and Multi-Qubits