A Continuous Pump-Probe Experiment to Observe Zeeman Wave Packet Dynamics
Abstract
In this work, we study the coherent dynamics of an atomic Zeeman wave packet using a continuous pump--probe scheme. A polarized wave packet is generated via few-photon excitation by a femtosecond laser pulse, creating a state with a magnetic moment tilted relative to an external magnetic field. The subsequent Larmor precession of the atoms is probed by continuous ionization in the field of an optical dipole trap (ODT) laser. Photoelectrons and photoions are detected in coincidence using a cold target recoil ion momentum spectrometer (COLTRIMS). While the addition of the ODT enables further cooling of the atomic ensemble, it removes the pulsed timing reference typically used to extract photoelectron momentum distributions in COLTRIMS. Here, we present a method that extends the standard COLTRIMS technique by exploiting redundancy in the measured data to reconstruct the time of ionization. The resulting time-dependent ionization signal reflects the coherent precession of the atomic magnetic moment, enabling real-time access to atomic dynamics on nanosecond timescales.
Cite
@article{arxiv.2502.06507,
title = {A Continuous Pump-Probe Experiment to Observe Zeeman Wave Packet Dynamics},
author = {Kevin L. Romans and Kyle Foster and Shruti Majumdar and Bishnu P. Acharya and Onyx Russ and A. H. N. C. De Silva and Daniel Fischer},
journal= {arXiv preprint arXiv:2502.06507},
year = {2025}
}