Memory effect of waves in disordered systems: a real-space approach

We present a real-space treatment of the memory effect which was recently proposed by Feng et al. [Phys. Rev. Lett. 61, 834 (1988)] for propagation of waves through a disordered system. The real-space approach provides physical insight for the effect. We extend the theory to include absorption and show that the memory effect is enhanced. The role of boundary conditions on the memory effect is also discussed.