Three Mach Zehnder Interferometers Setup for Production and Observation   of GHZ-entanglement of Electrons
  We propose a new single-step scheme for the generation of a GHZ entangled state of three single-electron excitations (flying qubits). We also present a method to get a generalized GHZ-state. Our idea relies upon the most recent progress in the field of on-demand electron sources and mesoscopic Mach-Zehnder interferometry. We also provide the recipe for the unambiguous detection of this GHZ state via correlations measurements at the output, which imply the violation of a Bell-type inequality which is generalized to the case of three particles. We explain how such measurements can be achieved in the context of Mach-Zehnder interferometry, and draw an actual prototype device which could be achieved with point contacts and metallic gates placed on a GaAs sample, in the integer quantum Hall effect regime. 
A. A. Vyshnevyy, G. B. Lesovik, T. Jonckheere and T. Martin
cond-mat.mes-hall quant-ph