Absolute strong-field ionization probabilities of ultracold rubidium atoms

Abstract

We report on precise measurements of absolute nonlinear ionization probabilities obtained by exposing optically trapped ultracold rubidium atoms to the field of an ultrashort laser pulse in the intensity range of 1 × 10 11 to 4 × 10 13 W/cm 2 . The experimental data are in perfect agreement with ab-initio theory, based on solving the time-dependent Schrödinger equation without any free parameters. Ultracold targets allow to retrieve absolute probabilities since ionized atoms become apparent as a local vacancy imprinted into the target density, which is recorded simultaneously. We study the strong-field response of 87 Rb atoms at two different wavelengths representing non-resonant and resonant processes in the demanding regime where the Keldysh parameter is close to unity.

Ultrafast electron cooling in an expanding ultracold plasma

“…At the highest intensity, the ionization probability reaches unity within the center region of a cylindrical volume depicted in Fig. 2b 21 . The radius of 1.35 μm is determined by the laser focus, while the height of 5 μm is limited by the target, thus providing a locally ionized volume within the atomic cloud (see Supplementary Note 1 ).…”

Long range propagation of ultrafast, ionizing laser pulses in a resonant nonlinear medium

“…It is very possible that this description with intensity dependent ionization rates is inaccurate as the PPT fomulas may have a limited validity for the three-and two-photon ionization processes of our case, especially for high intensities. A recent investigation of rubidium ionization [39] demonstrated that ab initio calculations were needed to achieve quantitative agreement with experiment, especially when light is resonant with transitions between bound states. The wavelengths studied are different from the 780 nm in this investigation, pulse durations are much longer and single-photon resonances were not studied.…”

Dynamics of a trapped ion in a quantum gas: effects of particle statistics

“…Here, we focus our attention on the second approach and investigate the cooling dynamics of a trapped ion immersed in either a bosonic or fermionic environment. Albeit the s-wave regime in hybrid traps has been attained with only fermionic atoms so far [11], several ongoing experiments involve bosonic ensembles [13,[21][22][23][24][25][26]. Up until now, however, a few theoretical studies have been undertaken in order to assess the impact of ion micromotion on the atom-ion quantum dynamics: a quantum mechanical calculation in one dimension (1D) [27,28], a semiclassical investigation of confinement-induced resonances in quasi-1D [29,30], and a 3D master equation analysis [31].…”