Maxime Pesche | Search arXiv

arXiv2026

From harmonic to sound-like oscillations in a quantum gas confined in a gravity compensated shell trap

We study the center of mass oscillations of a quantum gas in a shell shaped trap in the presence of a vertical force opposed to gravity. The measured harmonic frequency at the bottom of the shell is compared with an analytical formula for the trap potential including corrections beyond the rotating wave approximation. When gravity is partially compensated, a quartic correction to the harmonic motion has to be included due to the shell curvature. As gravity is nearly canceled, the quantum gas occupies a large fraction of the lower hemisphere. Driving the center of mass induces internal excitations in the quantum gas, whose time evolution is governed by the presence of sound waves. Relaxation processes induce a strong damping of the center of mass oscillation in this limit.

cond-mat.quant-gas↗

arXiv2026

Impact of light shift inhomogeneities on the contrast of light pulse atom interferometers

We study the loss of the contrast in an atom interferometer when increasing the duration of Raman mirror pulses, and find the contrast decay rate to increase with the interferometer duration. We attribute this effect to the transverse spatial fluctuations of the intensity across the Raman beams, and to the dephasing induced by the associated light shifts inhomogeneities. Simulations based on the propagation of noisy synthetic Raman beams show that the contrast decay rate increases with the distance between the wavepackets at the mirror pulse, before reaching an asymptotic limit when intensity fluctuations between the two wavepackets become completely decorrelated. Finally, simulations based on the propagation of Raman beams having their measured intensity fluctuations predict contrast loss rates consistent with our measurements, confirming the detrimental role for the interferometer contrast played by intensity fluctuations across the interferometer laser beams.

physics.atom-ph↗