Atom lithography of Fe

Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372 nm laser light standing wave to pattern a beam of iron atoms. In this proof-of-principle experiment, we have deposited a grid of 50-nm-wide lines 186 nm apart. These ultraregular, large-scale, ferromagnetic wire arrays may generate exciting new developments in the fields of spintronics and nanomagnetics. (C) 2004 American Institute of Physics

Direct Observation of Sub-Poissonian Temporal Statistics in a Continuous Free Electron Beam with Sub-picosecond Resolution

We present a novel method to measure the arrival time statistics of continuous electron beams with sub-ps resolution, based on the combination of an RF deflection cavity and fast single electron imaging. We observe Poissonian statistics within time bins from 100~ns to 2~ns and increasingly pronounced sub-Poissonian statistics as the time bin decreases from 2~ps to 340~fs. This 2D streak-camera in principle enables femtosecond-level arrival time measurements, paving the way to observing Pauli blocking effects in electron beams and thus serving as an essential diagnostic tool towards degenerate electron beam sources for free electron quantum optics

Atom lithography with two-dimensional optical masks

With a two-dimensional (2D) optical mask, nanoscale patterns are created for the first time in an atom lithography process using metastable helium atoms. The internal energy of the atoms is used to locally damage a hydrofobic resist layer, which is removed in a wet etching process. Experiments have been performed with several polarizations for the optical mask, resulting in different intensity patterns, and corresponding nanoscale structures. The results for a linear polarized light field show an array of holes with a diameter of 260 nm, in agreement with a computed pattern. With a circularly polarized light field a line pattern is observed with a spacing of 766 nm. Simulations taking into account many possible experimental imperfections can not explain this pattern.Comment: 5 pages, 4 figure

Blue laser cooling transitions in Tm I

We have studied possible candidates for laser cooling transitions in $^{169}$Tm in the spectral region 410 -- 420 nm. By means of saturation absorption spectroscopy we have measured the hyperfine structure and rates of two nearly closed cycling transitions from the ground state $4\textrm{f}^{13}6\textrm{s}^2(^2\textrm{F}_0)(J_g=7/2)$ to upper states $4\textrm{f}^{12}(^3\textrm{H}_5)5\textrm{d}_{3/2}6\textrm{s}^2(J_e=9/2)$ at 410.6 nm and $4\textrm{f}^{12}(^3\textrm{F}_4)5\textrm{d}_{5/2}6\textrm{s}^2(J_e=9/2)$ at 420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and 48(6) ns respectively. Decay rates from these levels to neighboring opposite-parity levels are evaluated by means of Hartree-Fock calculations. We conclude, that the strong transition at 410.6 nm has an optical leak rate of less then $2\cdot10^{-5}$ and can be used for efficient laser cooling of $^{169}$Tm from a thermal atomic beam. The hyperfine structure of two other even-parity levels which can be excited from the ground state at 409.5 nm and 418.9 nm is also measured by the same technique. In addition we give a calculated value of $7(2)$ s$^{-1}$ for the rate of magnetic-dipole transition at 1.14 $\mu$m between the fine structure levels $(J_g=7/2)\leftrightarrow(J'_g=5/2)$ of the ground state which can be considered as a candidate for applications in atomic clocks.Comment: 8 pages, 5 figure

Het scheermes van Ockham

No abstract

Quasi-Bragg scattering : beam splitters for atom interferometry

No text available

NNV-symposium over moderne rekenmachines

In oktober 1949 stond in het NTvN de tekst van een aantal voordrachten, gehouden tij dens het Symposium over Moderne Reken machines. Dit NNV-symposium vond plaats op 14 mei van dat jaar in het Natuurkundig Laboratorium van de Universiteit van Am sterdam. De NNV gaf hiermee blijk van een goede neus voor relevante nieuwe ontwik kelingen

Vijftig jaar AMOLF

Het FOM-lnstituut voor Atoom- en Molecuulfysica (AMOLF) neemt al lange tijd een belangrijke positie in bin nen de nationale en internationale onderzoeksgemeenschap op dit gebied. Hoewel het kiezeri van een oprichtingsdatum een beetje willekeurig is, zijn er goede redenen om te stellen dat het instituut deze maand 50 jaar bestaat

Quasi-Bragg scattering : beam splitters for atom interferometry

No text available

NNV-symposium over moderne rekenmachines

In oktober 1949 stond in het NTvN de tekst van een aantal voordrachten, gehouden tij dens het Symposium over Moderne Reken machines. Dit NNV-symposium vond plaats op 14 mei van dat jaar in het Natuurkundig Laboratorium van de Universiteit van Am sterdam. De NNV gaf hiermee blijk van een goede neus voor relevante nieuwe ontwik kelingen