I am using the code below, utilizing QETLAB's RandomStateVector(4) and IsPPT, to generate a random state and to judge whether the state is entangled or separable:
clear all; clc; for i = 1:30000 psi = RandomStateVector(4); rho = psi*psi'; if IsPPT(rho) 'yes' end end
But why does the program nearly never get inside the if block? I didn't see one single yes output. But the program works well, and if I use RandomDensityMatrix(4) instead, it's easy to see the output yes.
So, does it mean that for pure two qubits state, nearly all state are entangled?