# Single-particle emission at finite temperatures

## TL;DR

This paper investigates how finite temperature affects single-particle emission from Fermi sea sources, revealing symmetries that preserve single-particle regimes and analyzing temperature impacts on electrical and heat currents.

## Contribution

It uncovers a symmetry in the scattering amplitude that maintains single-particle emission at finite temperatures, extending zero-temperature results.

## Key findings

- Symmetry preserves single-particle emission at finite temperatures.
- Finite temperature induces mixed states from pure states at zero temperature.
- Temperature influences electrical and heat currents carried by single particles.

## Abstract

The state of particles injected onto the surface of the Fermi sea depends essentially on the temperature. The pure state injected at zero temperature becomes a mixed state if injected at finite temperature. Moreover the electron source injecting a single-particle state at zero temperature may excite a multi-particle state if the Fermi sea is at finite temperature. Here I unveil a symmetry of the scattering amplitude of a source, which is sufficient to preserve a single-particle emission regime at finite temperatures if such a regime is achieved at zero temperature. I give an example and analyze the effect of temperature on time-dependent electrical and heat currents carried by a single-particle excitation.