Photon Recoil Spectroscopy: Systematic Shifts and Nonclassical Enhancements

TL;DR

This paper develops a theoretical model for photon recoil spectroscopy using a Fokker-Planck equation, explaining systematic shifts and exploring quantum enhancements with nonclassical phonon states.

Contribution

It introduces a Fokker-Planck based model for photon recoil spectroscopy and investigates quantum metrological schemes for sensitivity enhancement.

Findings

Model accurately explains Doppler shift effects.

Systematic shifts due to heating and cooling are characterized.

Quantum schemes can improve spectroscopic sensitivity.

Abstract

In photon recoil spectroscopy, signals are extracted from recoils imparted by the spectroscopy light on the motion of trapped ions as demonstrated by C. Hempel et al., Nature Photonics 7, 630 (2013) and Y. Wan et al., Nature Communications 5, 3096 (2014). The method exploits the exquisite efficiency in the detection of phonons achievable in ion crystals, and is thus particularly suitable for species with broad non-cycling transitions where detection of fluorescence photons is impractical. Here, we develop a theoretical model for the description of photon recoil spectroscopy based on a Fokker-Planck equation for the Wigner function of the phonon mode. Our model correctly explains systematic shifts due to Doppler heating and cooling as observed in the experiment. Furthermore, we investigate quantum metrological schemes for enhancing the spectroscopic sensitivity based on the preparation and detection of nonclassical states of the phonon mode.