Boltzman optical thermometry for cryogenics

TL;DR

This paper introduces a novel optical method for measuring local temperatures in cryogenic environments using erbium-doped crystals, capable of accurately determining temperatures between 2-7 K and assessing interface conductance.

Contribution

It presents a new optical thermometry technique based on electron spin populations in erbium-doped crystals, suitable as a primary standard for cryogenic temperature measurements.

Findings

Accurately measures temperatures from 2 to 7 Kelvin.

Demonstrates the method's potential as a primary cryogenic standard.

Allows measurement of interface conductance with an auxiliary heating laser.

Abstract

We propose and implement an optical technique to access the local temperature of an erbium doped crystal by probing the electron spin population under magnetic field. We reliably extract the sample temperature in the range 2-7 K. We additionally discuss the suitability of our method as a primary standard for cryogenic thermometry. By adding an auxiliary heating laser, we are able to measure the interface conductance between the dielectric crystal and the cold plate of the cryostat by exploring different cooling configurations.