A single quantum dot as an optical thermometer for mK temperatures

TL;DR

This paper demonstrates that a single quantum dot can serve as an optical thermometer to measure temperatures as low as 100mK by analyzing spin state populations via resonant laser spectroscopy.

Contribution

It introduces a novel method of using a quantum dot as a highly sensitive optical thermometer for millikelvin temperature ranges.

Findings

Quantum dot spin states reflect reservoir temperature.

Resonant laser spectroscopy enables precise thermal measurements.

Effective down to 100mK temperatures.

Abstract

Resonant laser spectroscopy of a negatively charged self-assembled quantum dot is utilized to measure the temperature of a three dimensional fermionic reservoir down to 100mK. With a magnetic field applied to the quantum dot the single charged ground state is split by the Zeeman energy. As the quantum dot is in tunnel contact with a thermal electron reservoir, a thermal occupation of the quantum dot spin states is enforced by co-tunneling processes. Resonant laser induced fluorescence is used in order to measure the thermal quantum dot spin state population.