Effective rationality for local unitary invariants of mixed states of two qubits
Effective rationality for local unitary invariants of mixed states of two qubits
Abstract We calculate the field of rational local unitary invariants for mixed states of two qubits, by employing methods from algebraic geometry. We prove that this field is rational (i.e. purely transcendental), and that it is generated by nine algebraically independent polynomial invariants. We do so by constructing a relative …