Electronic heat transport across a molecular wire: Power spectrum of heat fluctuations

With this study we analyze the fluctuations of an electronic heat current across a molecular wire. The wire is composed of a single energy level, which connects two leads that are held at different temperatures. By use of the Green function method we derive an explicit expression for the power spectral density of the emerging heat noise. This result assumes a form that is quite distinct from the power spectral density of the accompanying electric current noise. The complex expression simplifies considerably in the limit of zero frequency, yielding the heat noise intensity. The heat noise spectral density still depends on the frequency in the zero-temperature limit, assuming different asymptotic behaviors in the low- and high-frequency regions. These findings evidence that heat transport across molecular junctions can exhibit a rich structure beyond the common behavior that emerges in the linear response limit.