Direct Imaging of Slow, Stored, and Stationary EIT Polaritons

Stationary and slow light effects are of great interest for quantum information applications. Using laser-cooled Rb87 atoms we have performed side imaging of our atomic ensemble under slow and stationary light conditions, which allows direct comparison with numerical models. The polaritions were generated using electromagnetically induced transparency (EIT), with stationary light generated using counter-propagating control fields. By controlling the power ratio of the two control fields we show fine control of the group velocity of the stationary light. We also compare the dynamics of stationary light using monochromatic and bichromatic control fields. Our results show negligible difference between the two situations, in contrast to previous work in EIT based systems

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

A Bright Solitonic Matter-Wave Interferometer

We present the first realisation of a solitonic atom interferometer. A Bose-Einstein condensate of $1\times10^4$ atoms of rubidium-85 is loaded into a horizontal optical waveguide. Through the use of a Feshbach resonance, the $s$-wave scattering length of the $^{85}$Rb atoms is tuned to a small negative value. This attractive atomic interaction then balances the inherent matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder interferometer is constructed by driving Bragg transitions with the use of an optical lattice co-linear with the waveguide. Matter wave propagation and interferometric fringe visibility are compared across a range of $s$-wave scattering values including repulsive, attractive and non-interacting values. The solitonic matter wave is found to significantly increase fringe visibility even compared with a non-interacting cloud.Comment: 6 pages, 4 figure

A quantum sensor: simultaneous precision gravimetry and magnetic gradiometry with a Bose-Einstein condensate

A Bose-Einstein condensate is used as an atomic source for a high precision sensor. A $5\times 10^6$ atom F=1 spinor condensate of $^{87}$Rb is released into free fall for up to $750$ms and probed with a Mach-Zehnder atom interferometer based on Bragg transitions. The Bragg interferometer simultaneously addresses the three magnetic states, $\left| m_f=1,0,-1 \right\rangle$, facilitating a simultaneous measurement of the acceleration due to gravity with an asymptotic precision of $2.1\times 10^{-9}$$\Delta$g/g and the magnetic field gradient to a precision $8$pT/m

Non-destructive shadowgraph imaging of ultracold atoms

An imaging system is presented that is capable of far-detuned non-destructive imaging of a Bose-Einstein condensate with the signal proportional to the second spatial derivative of the density. Whilst demonstrated with application to $^{85}\text{Rb}$, the technique generalizes to other atomic species and is shown to be capable of a signal to noise of ${\sim}25$ at $1$GHz detuning with $100$ in-trap images showing no observable heating or atom loss. The technique is also applied to the observation of individual trajectories of stochastic dynamics inaccessible to single shot imaging. Coupled with a fast optical phase lock loop, the system is capable of dynamically switching to resonant absorption imaging during the experiment.Comment: 4 pages, 5 figure