  Upstream neutral modes, counter propagating to charge modes and carrying
energy without net charge, had been predicted to exist in some of the
fractional quantum Hall states and were recently observed via noise
measurements. Understanding such modes will assist in identifying the
wavefunction of these states, as well as shedding light on the role of Coulomb
interactions within edge modes. In this work, performed mainly in the nu=2/3
state, we placed a quantum dot a few micrometers upstream of an ohmic contact,
which served as a neutral modes source. We showed the neutral modes heat the
input of the dot, causing a net thermo-electric current to flow through it.
Heating of the electrons led to a decay of the neutral mode, manifested in the
vanishing of the thermo-electric current at T>110mK. This setup provides a
straightforward method to investigate upstream neutral modes without turning to
the more cumbersome noise measurements.
