Probing a Bose-Einstein condensate with an atom laser

A pulsed atom laser derived from a Bose-Einstein condensate is used to probe a second target condensate. The target condensate scatters the incident atom laser pulse. From the spatial distribution of scattered atoms, one can infer important properties of the target condensate and its interaction with the probe pulse. As an example, we measure the s-wave scattering length that, in low energy collisions, describes the interaction between the |F = 1,mF = −1> and |F = 2,mF = 0> hyperfine ground states in 87Rb

Sudesna mjerenja u atomskoj spektroskopiji i analizama površina

The information obtainable from electron and X-ray spectroscopy studies can be increased significantly by the use of coincidence techniques. This entails detecting pairs of electrons and/or photons which are scattered or emitted from the same interaction event. This is illustrated by reference to Auger photoelectron coincidence spectroscopy. Some of the techniques currently being developed for enhancing the collection and display of coicidence data in atomic analysis spectroscopy are described. These include the use of microchannel plates and position sensitive detectors to provide parallel data collection of coincidence measurements. These can offer at least two orders of magnitude reduction in data collection time and lead to both energy dispersive and momentum dispersive displays in (e,2e) analyses. The possibility of using these procedures for surface and thin film analysis is discussed.Primjena sudesne metode u elektronskoj i rendgenskoj spektroskopiji omogućuje dobivanje znatno vrednijih eksperimentalnih podataka. Promatraju se parovi elektrona i/ili fotona koji su emitirani ili raspršeni u jednom događaju. Ova se metoda ilustrira Augerovom sudesnom spektroskopijom. Opisuju se neke nove metode za poboljšavanje sakupljanja podataka, kao mikrokanalne pločice i položajno osjetljivi detektori. Njima se brzina sabiranja podataka povećava i za više od dva reda veličine i omogućuje istovremena energijska i impulsna disperzijska analiza (e,2e) procesa. Raspravljaju se mogućnosti primjene tih metoda u istraživanju površina i tankih slojeva

Sudesna mjerenja u atomskoj spektroskopiji i analizama površina

The information obtainable from electron and X-ray spectroscopy studies can be increased significantly by the use of coincidence techniques. This entails detecting pairs of electrons and/or photons which are scattered or emitted from the same interaction event. This is illustrated by reference to Auger photoelectron coincidence spectroscopy. Some of the techniques currently being developed for enhancing the collection and display of coicidence data in atomic analysis spectroscopy are described. These include the use of microchannel plates and position sensitive detectors to provide parallel data collection of coincidence measurements. These can offer at least two orders of magnitude reduction in data collection time and lead to both energy dispersive and momentum dispersive displays in (e,2e) analyses. The possibility of using these procedures for surface and thin film analysis is discussed.Primjena sudesne metode u elektronskoj i rendgenskoj spektroskopiji omogućuje dobivanje znatno vrednijih eksperimentalnih podataka. Promatraju se parovi elektrona i/ili fotona koji su emitirani ili raspršeni u jednom događaju. Ova se metoda ilustrira Augerovom sudesnom spektroskopijom. Opisuju se neke nove metode za poboljšavanje sakupljanja podataka, kao mikrokanalne pločice i položajno osjetljivi detektori. Njima se brzina sabiranja podataka povećava i za više od dva reda veličine i omogućuje istovremena energijska i impulsna disperzijska analiza (e,2e) procesa. Raspravljaju se mogućnosti primjene tih metoda u istraživanju površina i tankih slojeva

Approaching the Heisenberg limit in an atom laser

We present experimental and theoretical results showing the improved beam quality and reduced divergence of an atom laser produced by an optical Raman transition, compared to one produced by an rf transition. We show that Raman outcoupling can eliminate the diverging lens effect that the condensate has on the outcoupled atoms. This substantially improves the beam quality of the atom laser, and the improvement may be greater than a factor of 10 for experiments with tight trapping potentials. We show that Raman outcoupling can produce atom lasers whose quality is only limited by the wave function shape of the condensate that produces them, typically a factor of 1.3 above the Heisenberg limit

Investigation and comparison of multi-state and two-state atom laser output-couplers

We investigate the spatial structure and temporal dynamics created in a Bose-Einstein condensate (BEC) by radio-frequency (RF) atom laser output-couplers using a one-dimensional mean-field model. We compare the behavior of a `pure' two-state atom laser to the multi-level systems demonstrated in laboratories. In particular, we investigate the peak homogeneous output flux, classical fluctuations in the beam and the onset of a bound state which shuts down the atom laser output.Comment: 9 pages, 8 figure

The Role of Source Coherence in Atom Interferometery

The role of source cloud spatial coherence in a Mach-Zehnder type atom interferometer is experimentally investigated. The visibility and contrast of a Bose-Einstein condensate (BEC) and three thermal sources with varying spatial coherence are compared as a function of interferometer time. At short times, the fringe visibility of a BEC source approaches 100 % nearly independent of pi pulse efficiency, while thermal sources have fringe visibilities limited to the mirror efficiency. More importantly for precision measurement systems, the BEC source maintains interference at interferometer times significantly beyond the thermal source

80hk Momentum Separation with Bloch Oscillations in an Optically Guided Atom Interferometer

We demonstrate phase sensitivity in a horizontally guided, acceleration-sensitive atom interferometer with a momentum separation of 80hk between its arms. A fringe visibility of 7% is observed. Our coherent pulse sequence accelerates the cold cloud in an optical waveguide, an inherently scalable route to large momentum separation and high sensitivity. We maintain coherence at high momentum separation due to both the transverse confinement provided by the guide, and our use of optical delta-kick cooling on our cold-atom cloud. We also construct a horizontal interferometric gradiometer to measure the longitudinal curvature of our optical waveguide.Comment: 6 pages, 6 figure

Semiclassical limits to the linewidth of an atom laser

We investigate the linewidth of a quasi-continuous atom laser within a semiclassical framework. In the high flux regime, the lasing mode can exhibit a number of undesirable features such as density fluctuations. We show that the output therefore has a complicated structure that can be somewhat simplified using Raman outcoupling methods and energy-momentum selection rules. In the weak outcoupling limit, we find that the linewidth of an atom laser is instantaneously Fourier limited, but, due to the energy `chirp' associated with the draining of a condensate, the long-term linewidth of an atom laser is equivalent to the chemical potential of the condensate source. We show that correctly sweeping the outcoupling frequency can recover the Fourier-limited linewidth.Comment: 9 Figure