“…In response to microwave radiation and dc bias, strongly nonlinear electron transport [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32] that gives rise to unusual electron states [33,34,35,36,37,38,39] has been reported in two-dimensional systems of highly mobile electrons in a high magnetic field. There has also been great interest in the nonlinear response of quantum ballistic constrictions, where the effects of quantum interference, spatial dispersion and electron-electron interaction play essential roles [40,41,42,43,44,45,46,47,48,…”