Thouless energy

The Thouless energy is a characteristic energy scale of diffusive disordered conductors. It is defined by E T = ℏ D / L 2 , where D is the diffusion constant and L the size of the system, and thereby inversely proportional to the diffusion time t D = L 2 / D through the system.

It was first introduced by the Scottish-American physicist David J. Thouless when studying Anderson localization, as a measure of the sensitivity of energy levels to a change in the boundary conditions of the system. Though being a classical quantity, it has been shown to play an important role in the quantum-mechanical treatment of disordered systems.