Nanofabrication by magnetic focusing of supersonic beams

We present a new method for nanoscale atom lithography. We propose the use of a supersonic atomic beam, which provides an extremely high-brightness and cold source of fast atoms. The atoms are to be focused onto a substrate using a thin magnetic film, into which apertures with widths on the order of 100 nm have been etched. Focused spot sizes near or below 10 nm, with focal lengths on the order of 10 microns, are predicted. This scheme is applicable both to precision patterning of surfaces with metastable atomic beams and to direct deposition of material.Comment: 4 pages, 3 figure

Quantum resonant effects in the delta-kicked rotor revisited

We review the theoretical model and experimental realization of the atom optics δ-kicked rotor (AOKR), a paradigm of classical and quantum chaos. We have performed a number of experiments with an all-optical Bose-Einstein condensate (BEC) in a periodic standing wave potential in an AOKR system. We discuss results of the investigation of the phenomena of quantum resonances in the AOKR. An interesting feature of the momentum distribution of the atoms obtained as a result of short pulses of light, is the variance of the momentum distribution or the kinetic energy ⟨p2⟩/2m in units of the recoil energy Erec = ħωrec. The energy of the system is examined as a function of pulse period for a range of kicks that allow the observation of quantum resonances. In particular we study the behavior of these resonances for a large number of kicks. Higher order quantum resonant effects corresponding to the fractional Talbot time of (1/4)TT and (1/5)TT for five and ten kicks have been observed. Moreover, we describe the effect of the initial momentum of the atoms on quantum resonances in the AOKR

Photon statistics in resonance fluorescence: results from an atomic-beam deflection experiment

Photon-number statistics in resonance fluorescence is studied through the deflection of a beam of neon atoms in the metastable 3P2 state by radiation pressure. An analysis of the deflection profile leads to experimental values for the Mandel Q parameter as a function of laser intensity and detuning for different laser polarizations. The results confirm the predicted predominantly sub-Poissonian statistics. Good agreement is demonstrated with the results of a Monte Carlo calculation based on a pure-state analysis of resonance fluorescence

Excitation dynamics and full counting statistics for resonant and off-resonant excitation of a strongly correlated cold Rydberg gas

Atoms in high-lying Rydberg states strongly interact with each other via the dipole-dipole or van der-Waals potential thus permitting the exploration of a wide range of many-body phenomena in strongly interacting systems. The strong interactions between Rydberg atoms under resonant laser driving become manifest either as spatial correlations compatible with a radius of blockade around an excited atom or through a reduction of fluctuations leading to sub-Poissonian statistics [1]. On the other hand, away from resonance, the detuning can compensate for the energy shift induced by the Rydberg-Rydberg interaction, giving rise to resonant interaction processes [2, 3]. In such an off-resonant excitation scheme, two atoms can undergo a pair excitation if the atomic interaction matches the laser energy defect/excess. As a consequence an already excited Rydberg atom pair (or a Rydberg atom, off-resonantly excited) can shift other atoms into resonance [4], in a domino effect, leading to an increasing overall number of Rydberg excitations. This resonant condition is the opposite of the blockade effect, where the interactions suppresses excitations, allowing at most one single excitation within a blockade radius. I will present experimental observations for both the resonant and the off-resonant excitation scheme, with the excitation laser having a finite detuning from the 87Rb 70S state. I will illustrate the off-resonant excitation dynamics and full counting statistics in experiments in which the growth of excitations is controlled by using an initial Rydberg excitation as a seed. The information extracted from the full counting distribution makes possible a direct comparison with theoretical predictions that is far more sensitive than, i.e., the mean and standard deviation alone

A bright metastable helium atomic beam for lithography and atom optics

Intense, highly collimated sources of atoms have many potential applications. Bright beams will be important for competitive high flux and high resolution direct-write techniques in lithography, with the added advantage of parallel writing through laser manipulation. Intense sources will also be useful in other atom optic devices e.g. for loading atoms into hollow fiber waveguides. In atomic physics, many collision processes can only be measured with the sensitivity offered by such high flux sources. We report progress on the development of an intense, collimated beam of metastable helium atoms which improves the brightness generated by conventional nozzle discharge sources by several orders of magnitude. The system uses diode lasers to transversely collimate and then to longitudinally slow the atoms, using Zeeman tuning to compensate for the changing Doppler shift. The slowed, collimated beam is then compressed in a 2D magneto-optic trap before a final collimation stage, to achieve the required increase in intensity. Initial experiments using the helium source for some of the applications above are described

Atomic beam brightener with a 1600-fold increase in intensity for Ne

The study of collisions between excited atoms requires high-intensity atomic beams to achieve detector signals of sufficient strength. Producing large densities of excited rare gas atoms R is especially difficult, since with conventional sources metastable atoms R make up a tiny fraction of ≈10-5 of the total beam flux. In such cases, 'brightening' the beam is the only way to achieve a sufficiently large flux. We have followed a scheme proposed by Metcalf to brighten an atomic beam of neon. The setup employs laser cooling on the Ne((3s)3P2 → (3p)3D3) cycling transition, and consists of three stages. First, we collimate all atoms emerging from a discharge source within a half-angle θ0 = 100 mrad. Second, the collimated beam is focused to a point. Third, the now converging beam is re-collimated to form a thin and bright atomic beam

Force and diffusion measurements in sub-Doppler laser cooling

We present the first direct measurements of the velocity dependence of the average force and diffusion constant for the metastable neon atoms in a one-dimensional σ+σ- laser cooling configuration. Force and diffusion are determined, respectively, from the deflection and broadening of a highly collimated atomic beam by its interaction with a pair of counter-running laser beams. The interaction time is much shorter than the characteristic damping time of the cooling process. The resulted force and diffusion measurements are compared with the results of both semiclassical and quantum Monte Carlo calculations