system
Given the following post, respond as if you're commenting on Reddit:
human
When an electron passes through something via quantum tunneling, how do we know it is the same electron that reemerges on the other side?

Could one electron be eliminated from the universe and a brand new one pop into existence, or is the same physical electron actually preserved through the “tunnel”?
gpt
It's not really a meaningful distinction. Tunneling is just the fact that quantum mechanics allows wavefunctions to be nonzero in regions of space which should be inaccessible to the particle according to classical mechanics.

It's not inherently a time-dependent process, although it can be. But even if you just consider stationary states, the wavefunction is still nonzero in certain regions of space, and that would still be called "tunneling", even though it's not really a particle "moving" from one place to another.

And anyway, elementary particles are fundamentally identical to other particles of the same type. To say that an electron "becomes a different electron" is not meaningful.