Phase coherence length
= Phase coherence length
{title2=$L_\phi$}
The characteristic distance over which phase-breaking processes suppress electron-path interference. For diffusion, $L_\phi\sim\sqrt{D\tau_\phi}$; ballistic phase propagation instead gives a scale $v\tau_\phi$. This differs from the elastic <mean free path>, since elastic scattering can change momentum while retaining coherence.