Multiple ionization of atoms in light field

We have excited helium atoms from their metastable 2 ${}^{3}\phantom{\rule{-0.16em}{0ex}}S$ state to Rydberg states in the range $13<n<50$ in a two-step process via the 3 ${}^{3}\phantom{\rule{-0.16em}{0ex}}P$ state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.We have excited helium atoms from their metastable 2 ${}^{3}\phantom{\rule{-0.16em}{0ex}}S$ state to Rydberg states in the range $13<n<50$ in a two-step process via the 3 ${}^{3}\phantom{\rule{-0.16em}{0ex}}P$ state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.

Physical Review ASep 6, 20116 citations

Multiphoton ionization of atoms

P. N. Lebedev

Jan 1, 19750 citations

Multiphoton Ionization of Atoms

P. L. Knight

Optica Acta International Journal of OpticsMar 1, 198523 citations

Generation of multiple electron beams by cold atom electron source

H.B. Wang, Haoyu Huang, Jianing Sun +4 more

Abstract We report the generation of multiple electron beams using a cold atom electron source (CAES) combined with a spatial light modulator (SLM). In the experiment, neutral ${ }^{87} \mathrm{Rb}$ atoms are confined in a magneto-optical trap and cooled to approximately $700 \mu \mathrm{~K}$ . By shaping the intensity profile of the excitation laser via the SLM, the spatial distribution of the excited atoms can be precisely controlled. The excited atoms are then ionized by a dye laser, and the ionized electrons are extracted and focused by an electric field to form multiple electron beams. As a demonstration, we generate regular arrays of $3 \times 3,4 \times 4,5 \times 5,6 \times 6$ beams, each with a spot size of about $100 \mu \mathrm{~m}$ and a normalized transverse emittance of $\sim 0.4 \times 10^{-9} \mathrm{~m} \cdot \mathrm{rad} \cdot \sqrt{\mathrm{eV}}$ . This programmable electron beam technique holds potential for applications in electron-beam lithography and wafer inspection.Abstract We report the generation of multiple electron beams using a cold atom electron source (CAES) combined with a spatial light modulator (SLM). In the experiment, neutral ${ }^{87} \mathrm{Rb}$ atoms are confined in a magneto-optical trap and cooled to approximately $700 \mu \mathrm{~K}$. By shaping the intensity profile of the excitation laser via the SLM, the spatial distribution of the excited atoms can be precisely controlled. The excited atoms are then ionized by a dye laser, and the ionized electrons are extracted and focused by an electric field to form multiple electron beams. As a demonstration, we generate regular arrays of $3 \times 3,4 \times 4,5 \times 5,6 \times 6$ beams, each with a spot size of about $100 \mu \mathrm{~m}$ and a normalized transverse emittance of $\sim 0.4 \times 10^{-9} \mathrm{~m} \cdot \mathrm{rad} \cdot \sqrt{\mathrm{eV}}$. This programmable electron beam technique holds potential for applications in electron-beam lithography and wafer inspection.

Chinese Physics BApr 27, 20260 citations

High-order above-threshold ionization of an atom in intense quantum light

Shijun Wang, XuanYang Lai

We investigate high-order above-threshold ionization (HATI) from intense quantum light-atom interaction, by numerically solving the fully quantum time-dependent Schr\"odinger equation based on quantum electrodynamics theory. Our simulations show that, in comparison with coherent-state (classical) light, the HATI spectra from intense quantum lights may have a higher cutoff energy and, moreover, for a given ponderomotive energy of the laser field, the cutoff energy is dependent on the laser wavelength and the ionization potential of the atom. The influence of quantum light on the HATI is revealed by examining the interplay between a quasiprobability distribution of the electric field of the quantum light and the Ammosov-Delone-Krainov ionization rate of the atom. Furthermore, analytical formulas of the cutoff energy of the HATI spectra for different quantum lights are derived.We investigate high-order above-threshold ionization (HATI) from intense quantum light-atom interaction, by numerically solving the fully quantum time-dependent Schr\"odinger equation based on quantum electrodynamics theory. Our simulations show that, in comparison with coherent-state (classical) light, the HATI spectra from intense quantum lights may have a higher cutoff energy and, moreover, for a given ponderomotive energy of the laser field, the cutoff energy is dependent on the laser wavelength and the ionization potential of the atom. The influence of quantum light on the HATI is revealed by examining the interplay between a quasiprobability distribution of the electric field of the quantum light and the Ammosov-Delone-Krainov ionization rate of the atom. Furthermore, analytical formulas of the cutoff energy of the HATI spectra for different quantum lights are derived.

Physical Review ADec 1, 202328 citations

We have excited helium atoms from their metastable 2

{}^{3}\phantom{\rule{-0.16em}{0ex}}S

state to Rydberg states in the range

13<n<50

in a two-step process via the 3

{}^{3}\phantom{\rule{-0.16em}{0ex}}P

state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.

Abstract We report the generation of multiple electron beams using a cold atom electron source (CAES) combined with a spatial light modulator (SLM). In the experiment, neutral

{ }^{87} \mathrm{Rb}

atoms are confined in a magneto-optical trap and cooled to approximately

700 \mu \mathrm{~K}

. By shaping the intensity profile of the excitation laser via the SLM, the spatial distribution of the excited atoms can be precisely controlled. The excited atoms are then ionized by a dye laser, and the ionized electrons are extracted and focused by an electric field to form multiple electron beams. As a demonstration, we generate regular arrays of

3 \times 3,4 \times 4,5 \times 5,6 \times 6

beams, each with a spot size of about

100 \mu \mathrm{~m}

and a normalized transverse emittance of

\sim 0.4 \times 10^{-9} \mathrm{~m} \cdot \mathrm{rad} \cdot \sqrt{\mathrm{eV}}

. This programmable electron beam technique holds potential for applications in electron-beam lithography and wafer inspection.