Transport inefficiency in branched-out mesoscopic networks: An analog of   the Braess paradox
  We present evidence for a counter-intuitive behavior of semiconductor mesoscopic networks that is the analog of the Braess paradox encountered in classical networks. A numerical simulation of quantum transport in a two-branch mesoscopic network reveals that adding a third branch can paradoxically induce transport inefficiency that manifests itself in a sizable conductance drop of the network. A scanning-probe experiment using a biased tip to modulate the transmission of one branch in the network reveals the occurrence of this paradox by mapping the conductance variation as a function of the tip voltage and position. 
M. G. Pala, S. Baltazar, P. Liu, H. Sellier, B. Hackens, F. Martins,   V. Bayot, X. Wallart, L. Desplanque, S. Huant
cond-mat.mes-hall