Polynomial invariants of four qubits
Jean-Gabriel Luque, Jean‐Yves Thibon · Physical Review A · 2003
We describe explicitly the algebra of polynomial functions on the Hilbert space of four-qubit states that are invariant under the group $\mathrm{SL}(2,C{)}^{4}$ of stochastic local quantum operations assisted by classical communication. From this description, we obtain a closed formula for the hyperdeterminant in terms of low degree invariants.