Calibration-free measurement of the phonon temperature around a single emitter

TL;DR

This paper introduces a calibration-free optical method to measure the local phonon temperature around a single emitter by analyzing phonon sidebands, validated on a quantum dot system, revealing heating effects under non-resonant excitation.

Contribution

The paper presents a novel, calibration-free technique for directly measuring the phonon temperature around a single emitter using phonon sideband ratios, applicable across various materials.

Findings

Quantum dot heats up under increased non-resonant excitation at low temperatures.

The method accurately measures local phonon temperature without prior calibration.

Thermal conductivity drops at low temperatures contribute to heating effects.

Abstract

The emission properties of a localized solid-state emitter are strongly influenced by its environment. The coupling to acoustic phonons impacts the coherence of the emitter and its temperature dependence, and also results in the apparition of phonon sidebands besides the sharp zero-phonon line. Here, we present a method for measuring the absolute temperature of a localized emitter by directly plotting the ratio of the Stokes and anti-Stokes components of the phonon sideband as a function of the shift from the zero-phonon line. This approach requires no calibration and knowledge of the system, making it applicable to a wide range of emitters and materials. We validate the method using a CdSe quantum dot in a ZnSe nanowire. We thus show that the quantum dot is significantly heated under non-resonant excitation when increasing the incident power at low temperature and is ascribed to the drop in thermal conductivity at these temperatures.