General bounds on electronic shot noise in the absence of currents

TL;DR

This paper establishes a universal bound on charge shot noise in two-terminal mesoscopic conductors without currents, highlighting fundamental differences between charge and heat noise behaviors under nonequilibrium conditions.

Contribution

It provides the first general bound on charge shot noise in the absence of currents, independent of conductor details and nonequilibrium states.

Findings

Charge shot noise never exceeds thermal noise in such systems.

No universal bound exists for heat shot noise under zero-current conditions.

Fundamental difference between charge and heat noise bounds is demonstrated.

Abstract

We investigate the charge and heat electronic noise in a generic two-terminal mesoscopic conductor in the absence of the corresponding charge and heat currents. Despite these currents being zero, shot noise is generated in the system. We show that, irrespective of the conductor's details and the specific nonequilibrium conditions, the charge shot noise never exceeds its thermal counterpart, thus establishing a general bound. Such a bound does not exist in the case of heat noise, which reveals a fundamental difference between charge and heat transport under zero-current conditions.