  Counter propagating (upstream) chiral neutral edge modes, which were
predicted to be present in hole-conjugate states, were observed recently in a
variety of fractional quantum Hall states (v=2/3,v=3/5,v=8/3 & v=5/2), by
measuring charge noise that resulted after partitioning the neutral mode by a
constriction (denoted, as N\rightarrowC). Particularly noticeable was the
observation of such modes in the v=5/2 fractional state - as it sheds light on
the non-abelian nature of the state's wavefunction. Yet, the nature of these
unique, upstream, chargeless modes and the microscopic process in which they
generate shot noise, are not understood. Here, we study the ubiquitous v=2/3
state and report of two main observations: First, the nature of the neutral
modes was tested by 'colliding' two modes, emanating from two opposing sources,
in a narrow constriction. The resultant charge noise was consistent with local
heating of the partitioned quasiparticles. Second, partitioning of a downstream
charge mode by a constriction gave birth to a dual process, namely, the
appearance of an upstream neutral mode (C\rightarrowN). In other words,
splitting 'hole conjugated' type quasiparticles will lead to an energy loss and
decoherence, with energy carried away by neutral modes.
