Electronic Thermal Transport Measurement in Low-Dimensional Materials with Graphene Nonlocal Noise Thermometry

In low-dimensional systems, the combination of reduced dimensionality, strong interactions, and

topology has led to a growing number of many-body quantum phenomena. Thermal transport, which

is sensitive to all energy-carrying degrees of freedom, provides a discriminating probe of emergent

excitations in quantum materials and devices. However, thermal transport measurements in low

dimensions are dominated by the phonon contribution of the lattice, requiring an experimental

approach to isolate the electronic thermal conductance. Here, we show how the measurement of

nonlocal voltage fluctuations in a multiterminal device can reveal the electronic heat transported

across a mesoscopic, low-dimensional bridge. By using two-dimensional graphene as

a noise thermometer, we demonstrate quantitative electronic thermal conductance measurements of

graphene and carbon nanotubes up to 70 K, achieving a precision of ~1% of the thermal conductance

quantum at 5 K. Employing linear and nonlinear thermal transport, we observe signatures of long range

interaction-mediated energy transport in one-dimensional electron systems, in agreement with a

theoretical model. Our versatile nonlocal noise thermometry allows new experiments probing energy

transport in emergent states of matter and devices in low dimensions.