* Both authors equally contributed to this work

One of the predicted properties of the quasi-particles emerging in the fractional quantum Hall effect is their unique statistics. They are expected to have fractional statistics, which is different from the well known Fermi-Dirac or Bose-Einstein statistics.

 In contrast to most proposals that suggest to observe the statistics via interference measurement, we tried to verify its existence by measuring the cross-correlation between partitioned beams of quasi-particles by quantum point contacts (QPCs).

 Our sample consisted two such QPCs, each serving as a beam splitter for the current propagating along the edge. The two QPCs were placed in series such that the transmitted part from the first QPC (being a dilute beam of quasi-particles) arrives at the second QPC.

 In the first experiment we measured the cross-correlation between current fluctuations (shot noise) of reflected current from the first QPC and the transmitted current of the second QPC. We compared our results to a simple non-interacting fermionic model. The data at both nu=1 and nu=1/3 fitted well to such a model - reviling no signature of fractional statistics (although such a signature was expected in a similar geometry [1]). 

 In the second experiment we measured the cross correlation between current fluctuations of the transmitted and reflected currents from the second QPC (the first QPC was used to dilute the impinging beam of quasi-particles). Comparing our data to a similar non-interacting fermionic model gave a good fit at nu=1 and a clear deviation at nu=1/3. This striking deviation might be signature of the fractional statistics, although no theory exists yet to substantiate it.

[1] I. Safi, P. Devillard, T. Martin, Phys. Rev. Lett. 86, 4628–4631 (2001)