% example_maxppt Example for the application of maxppt % This example computes the maximum for the operator Jx^2+Jy^2 % for states that are PPT with respect to some bipartition of the qubits. % Similar otimisation is carried out in http://arxiv.org/abs/0903.3910. echo on % Looking for maximum for Jx^2+Jy^2 for states that are biseparable % with respect to some bipartition of the qubits % Number of qubits N=4; % Define Pauli spin matrices x,y,z and e paulixyz; % Define the collective angular momentum components Jx=coll(x,N)/2; Jy=coll(y,N)/2; Jz=coll(z,N)/2; % Define the operator for which we look for the maximum M=Jx^2+Jy^2; % Maximum for the 1:234 partition max1=maxppt(M,1) % Maximum for the 12:34 partition max12=maxppt(M,1:2) echo off