Single-particle shot noise at non-zero temperature

TL;DR

This paper analyzes how finite temperature affects shot noise generated by single particles passing through a quantum point contact, revealing changes in quantum states and correlations that influence noise levels.

Contribution

It provides a detailed analysis of temperature-dependent effects on shot noise, including state purity, orthogonality, and particle correlations, with experimental distinction methods.

Findings

Shot noise is suppressed for mixed states compared to pure states.

Temperature induces correlations that enhance shot noise.

Antibunching effects suppress shot noise at finite temperature.

Abstract

The state of a single particle injected onto the surface of the Fermi sea is a pure state if the temperature is zero and is a mixed state if the temperature is finite. Moreover, the state of an injected particle is orthogonal to the state of the Fermi sea at zero temperature, while it is not orthogonal at non-zero temperature. These changes in the quantum state of the injected particles can be detected using the temperature dependence of the shot noise that is generated when the particles one by one pass through a semitransparent quantum point contact. Namely, the shot noise produced by the mixed state is suppressed in comparison with the noise of the pure state. In addition, the correlations between the injected particles and the underlying Fermi sea, present at non-zero temperature, do enhance the shot noise. Furthermore, antibunching of injected particles with possible thermal excitations coming from another input channel of a quantum point contact does suppress shot noise. Here I analyze in detail these three effects, which are responsible for the temperature dependence of the shot noise, and discuss how to distinguish them experimentally.