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Register a new userDynamic Manipulation of Bose-Einstein Condensates With a Spatial Light Modulator
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We manipulate a Bose-Einstein condensate using the optical trap created by the diffraction of a laser beam on a fast ferro-electric liquid crystal spatial light modulator. The modulator acts as a phase grating which can generate arbitrary diffraction patterns and be rapidly reconfigured at rates up to 1 kHz to create smooth, time-varying optical potentials. The flexibility of the device is demonstrated with our experimental results for splitting a Bose-Einstein condensate and independently transporting the separate parts of the atomic cloud.
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We present a detailed theoretical analysis of the implementation of shortcut-to-adiabaticity protocols for the fast transport of neutral atoms with atom chips. The objective is to engineer transport ramps with durations not exceeding a few hundred milliseconds to provide metrologically-relevant input states for an atomic sensor. Aided by numerical simulations of the classical and quantum dynamics, we study the behavior of a Bose-Einstein condensate in an atom chip setup with realistic anharmonic trapping. We detail the implementation of fast and controlled transports over large distances of several millimeters, i.e. distances 1000 times larger than the size of the atomic cloud. A subsequent optimized release and collimation step demonstrates the capability of our transport method to generate ensembles of quantum gases with expansion speeds in the picokelvin regime. The performance of this procedure is analyzed in terms of collective excitations reflected in residual center of mass and size oscillations of the condensate. We further evaluate the robustness of the protocol against experimental imperfections.
We demonstrate the ability to excite atoms at well-defined, programmable locations in a magneto-optical trap, either to the continuum (ionisation), or to a Rydberg state. To this end, excitation laser light is shaped into arbitrary intensity patterns with a spatial light modulator. These optical patterns are sensitive to aberrations of the phase of the light field, occuring while traversing the optical beamline. These aberrations are characterised and corrected without observing the actual light field in the vacuum chamber.
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Due to their unique coherence properties, Bose-Einstein condensates are ideal sources for an atom interferometer in extended free fall. In this paper we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far-field of a double-slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
We demonstrate detection of a weak alternate-current magnetic field by application of the spin echo technique to F = 2 Bose-Einstein condensates. A magnetic field sensitivity of 12 pT/Hz^1/2 is attained with the atom number of 5*10^3 at spatial resolution of 99 mu m^2. Our observations indicate magnetic field fluctuations synchronous with the power supply line frequency. We show that this noise is greatly suppressed by application of a reverse phase magnetic field. Our technique is useful in order to create a stable magnetic field environment, which is an important requirement for atomic experiments which require a weak bias magnetic field.
Producing a substantial and stable resonant Bose-Einstein condensate (BEC) has proven to be a challenging experimental task due to heating and three-body losses that may occur even before the gas comes to thermal equilibrium. In this paper, by considering only two-body correlations, we note that a sudden quench from small to large scattering lengths may not be the best way to prepare a resonant BEC. As an alternative, we propose a two-step scheme that involves an intermediate scattering length, between $0$ and $infty$, which serves to maximize the transfer probability of $N$ bosons of mass $m$ in a harmonic trap with frequency $omega$. We find that the intermediate scattering length should be $aapprox3.16N^{-2/3}sqrt{hbar/(momega)}$ to produce an optimum transition probability of $1.03N^{-1/6}$.
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