Charge, spin, and heat shot noises in the absence of average currents: Conditions on bounds at zero and finite frequencies

Low Temperature Probing of On-Surface Dynamical Fluctuations with Johnson-Nyquist and Delta-T Noises

“…The quantity we wish to calculate is the current-current correlations in one of the contacts connecting a reservoir with the studied mesoscopic sample. Following the papers [10,19],…”

“…Let us mention again that the notion of zero-current charge noise in the presence of a temperature bias originally proposed in the paper [8] for electronic correlations at zero frequency was recently generalized to the case of finite frequencies in two recent works [10,11]. In both works, the authors studied a spectral density not only for constant scattering but also for a narrow transport window as an example of the energy-dependent transmission.…”

“…Because of it, current and noise corresponding to the average and variance of the number of electrons passing through a conductor per unit time can provide different (and mutually complementary) information on a transport mechanism. Even more, current noise arising due to the discrete nature of the carriers in mesoscopic nanoscale samples and probing thus their granularity can emerge in the absence of an average current 0 I  [8][9][10]. In particular, it can occur due to a temperature bias when the voltage bias V = 0.…”

“…Since the effect of nonequilibrium electronic fluctuations is the result of the integration over excitation energies, the delta-T noise dependence on the temperature difference T at the ends of a two-terminal conductor with energy-independent electron scattering is featureless. Noticeable nontrivial behavior arises in the case of a significant energy dependence of the charge transmission probability across the sample that can be realized in the presence of a resonant level [9][10][11] or in a tunnel junction between helical edge states [12].…”

“…Notice that previous activities were mainly focused on the low-frequency limit of shot noise while, as was stressed in the review [13], "shot noise becomes frequency-dependent and sometimes provides essential information on electron dynamics at high frequencies". The authors of the works [10,11] discussed the finite-frequency limit of the shot noise in delta-T-driven mesoscopic conductors while in the context of quantum nanophysics, our aim was to study the response of the discussed characteristic to oscillating potentials. Below, we present a scattering approach to the probabilistic transport in nanoscale conductors and related numerical simulations of the Johnson-Nyquist noise and the delta-T noise at frequency ω.…”