Revival of electron coherence in a quantum wire of finite length.

We study the spatial decay of electron coherence due to electron-electron interaction in a finite-length disorder-free quantum wire. Based on the Luttinger liquid theory, we demonstrate that the coherence length characterizing the exponential decay of the coherence can vary from region to region, and that the coherence can even revive after the decay. This counterintuitive behavior, which is in clear contrast to the conventional exponential decay with single coherence length, is due to the fractionalization of an electron and the finite-size-induced recombination of the fractions.