Fast thermometry for trapped ions using dark resonances

TL;DR

This paper introduces a rapid and accurate method for measuring the temperature of trapped ions by analyzing dark resonance lineshapes in fluorescence spectra, suitable for monitoring fast thermalization processes.

Contribution

The authors demonstrate a novel thermometry technique using dark resonances that allows for quick, accurate temperature measurements of single ions and small crystals within microseconds.

Findings

Achieves temperature measurement accuracy better than 15% over 0.1 to 100 mK range.

Allows rapid temperature determination in 20 microseconds.

Enables control of ion temperatures between 0.7 mK and over 10 mK.

Abstract

We experimentally demonstrate a method to determine the temperature of trapped ions which is suitable for monitoring fast thermalization processes. We show that observing and analyzing the lineshape of dark resonances in the fluorescence spectrum provides a temperature measurement which accurate over a large dynamic range, applied to single ions and small ion crystals. Laser induced fluorescence is detected over a time of only $20\,\mu$s allowing for rapid determination of the ion temperature. In the measurement range of $10^{-1}-10^{+2}\,$mK we reach better than $15\,\%$ accuracy. Tuning the cooling laser to selected resonance features allows for controlling the ion temperatures between $0.7\,$mK and more than $10\,$mK. Experimental work is supported by a solution of the 8-level optical Bloch equations when including the ions classical motion. This technique paves the way for many experiments comprising heat transport in ion strings, heat engines, non-equilibrium thermodynamics or thermometry of large ion crystals.