Single-particle entanglement

I give a simple argument that demonstrates that the state vertical bar 0> vertical bar 1>+ vertical bar 1> vertical bar 0>, with |0> denoting a state with 0 particles (or photons) and vertical bar 1> a one-particle state, is entangled in spite of recent claims to the contrary. I also discuss viewpoints on the old controversy about whether the above state can be said to display single-particle or single-photon nonlocality.