# Can one make already separate atoms/electrons entangled?

Is it possible to make two separate atoms or electrons entangled on a quantum level? Not photons, those I know can be entangled already

Say you shoot two atoms against each other in a collision experiment. At $$t=0$$ the atoms have a definite momentum $$\hbar k$$, $$|\Psi \rangle = |k\rangle |-k \rangle$$. After the collision, they will be in a superposition of different momenta, but the interaction is such that the total momentum must be conserved. Hence the resulting state will look roughly like this
$$|\Psi \rangle \approx c_1 |k_1\rangle |-k_1 \rangle + c_2|k_2\rangle |-k_2 \rangle +...$$