Resonant Correlation-Induced Optical Bistability in an Electron System on Liquid Helium

We show that electrons on liquid helium display intrinsic bistability of resonant inter-subband absorption. The bistability occurs for comparatively weak microwave power. The underlying giant nonlinearity of the many-electron response results from the interplay of the strong short-range electron correlations, the long relaxation time, and the multi-subband character of the electron energy spectrum.