# Thermal transistor and thermometer based on Coulomb-coupled conductors

## TL;DR

This paper explores a Coulomb-coupled quantum dot setup that functions as both a nanoscale thermal transistor and thermometer, enabling precise control and measurement of heat and charge flow at the quantum level.

## Contribution

It introduces a novel quantum dot-based device capable of switching between thermal transistor and thermometer functionalities with optimized sensitivity.

## Key findings

- Device can operate as a high-sensitivity thermal transistor.
- Device can perform noninvasive nanoscale thermometry.
- Optimal conditions for maximum sensitivity are derived.

## Abstract

We study a three-terminal setup consisting of a single-level quantum dot capacitively coupled to a quantum point contact. The point contact connects to a source and drain reservoirs while the quantum dot is coupled to a single base reservoir. This setup has been used to implement a noninvasive, nanoscale thermometer for the bath reservoir by detecting the current in the quantum point contact. Here, we demonstrate that the device can also be operated as a thermal transistor where the average (charge and heat) current through the quantum point contact is controlled via the temperature of the base reservoir. We characterize the performances of this device both as a transistor and a thermometer, and derive the operating condition maximizing their respective sensitivities. The present analysis is useful for the control of charge and heat flow and high precision thermometry at the nanoscale.