All-optical matter-wave lens using time-averaged potentials

Abstract

The precision of matter-wave sensors benefits from interrogating large-particle-number atomic ensembles at high cycle rates. Quantum-degenerate gases with their low effective temperatures allow for constraining systematic errors towards highest accuracy, but their production by evaporative cooling is costly with regard to both atom number and cycle rate. In this work, we report on the creation of cold matter-waves using a crossed optical dipole trap and shaping them by means of an all-optical matter-wave lens. We demonstrate the trade off between lowering the residual kinetic energy and increasing the atom number by reducing the duration of evaporative cooling and estimate the corresponding performance gain in matter-wave sensors. Our method is implemented using time-averaged optical potentials and hence easily applicable in optical dipole trapping setups.

Matter-wave collimation to picokelvin energies with scattering length and potential shape control

“…Through dedicated theory simulations, we extrapolate this result to two dimensions, yielding a 2D energy below 500 pK. We hence demonstrate a substantial improvement over previous results achieved with the same method and setup using 87 Rb 52 . Furthermore, our systematic analysis reveals that the careful adjustment of trapping frequencies and interactions will allow to reach 3D expansion energies below 16 pK, when implementing an additional deltakick collimation (DKC) pulse 43 after a few milliseconds of free fall.…”

“…We apply the matter-wave lensing protocol as described by Albers et al 52 . A detailed overview of the setup is provided in the experimental apparatus section.…”

Rapid generation of all-optical 39K Bose-Einstein condensates using a low-field Feshbach resonance

“…The modulation reaches amplitudes of up to 200 μm in the primary and 300 μm in the secondary recycled beam. By this we generate time-averaged potentials [24,26,48] in the horizontal plane. The shape of the resulting potential depends on the modulation of the AOM driving radio frequency, which is generated using a voltagecontrolled oscillator [Mini-Circuits, ZOS − 150+] controlled by the output of an arbitrary waveform generator [Rigol, DG1022Z].…”

“…In addition, BECs offer routes to create entanglement via one-axis twisting dynamics [69] or delta-kick squeezing techniques [70] and routes to transfer spin squeezing to momentum states have been demonstrated [71]. For the specific case of 39 K, one approach to circumvent the BEC's inherent instability in absence of Feshbach magnetic fields during the interferometer is to exploit ballistic expansion with subsequent matter-wave lensing [11,26,72] to operate at low densities. On the other hand, applications in trapped interferometry using optical guiding potentials will benefit from tunable interactions [73,74], e.g., to mitigate phase diffusion due to collisions.…”

“…Accordingly, lowering the trap depth, as demanded for evaporative cooling, leads to a loss of peak atomic density and elastic-scattering rate, thus inhibiting efficient cooling. Recent studies have shown a variety of tools to counteract these scaling laws [22], e.g., by movable lens systems [23] enabling a tunable increase in confinement by tighter optical waists or dynamically shaped time-averaged potentials [24][25][26]. Finally, while trapping any substate irrespective of high or low magnetic-field seeking, with the external magnetic field as a free parameter optical traps offer ideal conditions for studying and utilizing Feshbach resonances [27,28].…”