Quantum tomography of electrical currents*

Recent developments in quantum nanoelectronics have enabled the realization of electron sources emitting a quantized number of excitations. However, reconstructing all wavefunctions of the elementary excitations embedded in electrical currents was still out of reach.
Combining two-electron Hong-Ou-Mandel interferometry [1] with signal processing techniques, we demonstrate a quantum tomography protocol [2, 3, 4] able of extracting from any electrical current the generated electron and hole wavefunctions as well as their emission probabilities. The interferometer is implemented in a 2D electron gas in the integer quantum Hall effect where charges propagate along 1D ballistic edge channels. First we demonstrate the protocol with sinusoidal currents which allow for simple comparison with theoretical predictions. Then we turn to periodic single electron Lorentzian pulses and show that thermal effects lead to the generation of a statistical mixture between two single-electron wavefunctions.
[1]E.Bocquillon et al. Science 339, 1054 (2013)
[2]C.Grenier et al. NJP 13, 093007 (2011)
[3]T.Jullien et al. Nature 514, 603 (2014)
[4]A.Marguerite et al. arXiv:1710.11181