Universality and quantization of the power-to-heat ratio in nanogranular systems

We study heating and dissipation effects in granular nanosystems in the regime of weak coupling between the grains. We focus on the cotunneling regime and solve the heat-dissipation problem in an array of grains exactly. We show that the power to heat ratio has a universal quantized value, which is geometrically protected: It depends only on the number of grains.