I have notions of the mathematics involving (entangled state is one which is not a product state of two qubits, etc) the idea of entanglement. However, still can not figure out how to, let us say, pick a particle (which type of particle we can use as qubit? protons? electrons? ununumbiums!?!?) A in one laboratory of Max Planck and a particle B in Boston and then entangle them. How can we entangle 2 arbitrary particles?