Dynamic Majorana resonances and universal symmetry of nonequilibrium thermoelectric quantum noise

Nonequilibrium states of a nanoscopic system may be achieved by both applying a bias voltage $V$ to its contacts and producing a difference $\Delta T$ in their temperatures. Then the total current results from two competing flows, induced by $V$ and $\Delta T$, respectively. Here we explore finite frequency quantum noise of this thermoelectric current flowing through a quantum dot whose low-energy dynamics is governed by Majorana degrees of freedom. We demonstrate that at finite frequency $\omega$ Majorana zero modes induce a perfect universal symmetry between photon emission and absorption spectra and produce universal thermoelectric resonances in their frequency dependence in contrast to non-Majorana quantum noise which is either asymmetric or non-universal. In particular, at low temperatures the differential thermoelectric quantum noise induced by Majorana zero modes shows resonances with a nontrivial maximum $\frac{e^3}{h}\log(2^{1/4})$ at $\omega=\mp\frac{|eV|}{\hbar}$ when $k_\text{B}\Delta T\ll|eV|$. Our results challenge cutting-edge experiments using quantum noise detectors to reveal the universal spectral symmetry and resonant structure of the Majorana thermoelectric finite frequency quantum noise.