Demonstration of a Raman Velocity Filter in Collinear Laser Spectroscopy: Towards Applications for sub-ppm High-Voltage Measurements

TL;DR

This paper demonstrates a novel velocity filter using Raman transitions in collinear laser spectroscopy of $^{88}$Sr$^+$ ions, achieving high precision and reduced energy width, with potential applications in high-voltage measurements.

Contribution

It presents the first experimental realization of a velocity-selective Raman transition in collinear laser spectroscopy, improving energy resolution significantly.

Findings

Achieved energy width reduction to less than 200 meV.

Demonstrated two-photon Rabi oscillations consistent with simulations.

First velocity-selective Raman transition in collinear laser spectroscopy.

Abstract

Raman transitions have a wide range of applications in atomic physics and have recently been proposed as a means for improving high-precision high-voltage measurements. Here, we present a theoretical analysis and a first experimental demonstration of $5s\,^2\mathrm{S}_{1/2} \rightarrow 4d\,^2\mathrm{D}_{3/2,5/2}$ Raman transitions in $^{88}$Sr$^+$ ions in collinear laser spectroscopy. For the theoretical description the three-level system is reduced to an effective two-level system, in order to estimate the experimental parameters, while the role of the spatial laser intensity distribution in combination with the radial extension of the ion beam are elucidated by performing simulations of the full four-level system. Experimentally, we realized the first velocity-selective Raman transition in collinear laser spectroscopy. Using a $^{88}$Sr$^+$ ion beam, we demonstrate a reduction in the energy width to less than $200\,$meV, which is about an order of magnitude reduction compared to the usage of an optical dipole transition as in previous works. We also investigate two-photon Rabi oscillations and show that their observed collapse is consistent with the simulations.