arXiv subjects

F. Nogrette

Publications and source records attributed to F. Nogrette.

3 recordsLinked to original sources

arXiv2023

Probing the local rapidity distribution of a 1D Bose gas

One-dimensional Bose gases with contact repulsive interactions are characterized by the presence of infinite-lifetime quasiparticles whose momenta are called the `rapidities'. Here we develop a probe of the local rapidity distribution, based on the fact that rapidities are the asymptotic momenta of the particles after a long one-dimensional expansion. This is done by performing an expansion of a selected slice of the gas. We first apply this idea to a cloud in the quasi-condensate regime at equilibrium in a trap. We obtain an experimental picture of the position-dependent rapidity distribution which is in fair agreement with the theory prediction. The asymptotic regime is barely reached, but we show that finite expansion time can be taken into account using the Generalized Hydrodynamics theory. We then apply this local probe to an out-of-equilibrium situation where the local rapidity distribution is expected to be doubly peaked -- a hallmark of a non-thermal state -- even though the global rapidity distribution would possess no such distinctive feature. We observe the doubly-peaked local rapidity distribution.

cond-mat.quant-gas↗

arXiv2015

Characterization of a detector chain using a FPGA-based Time-to-Digital Converter to reconstruct the three-dimensional coordinates of single particles at high flux

We report on the development of a novel FPGA-based Time-to-Digital Converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of Micro-Channel Plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1x10^6 per second and three-dimensional reconstruction of the coordinates up to 3.2x10^6 particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) um. In addition we analyze a method to measure the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work directly apply to the detection of other kinds of particles.

physics.ins-det↗

arXiv2015

Fast production of Bose-Einstein condensates of metastable Helium

We report on the Bose-Einstein condensation of metastable Helium-4 atoms using a hybrid approach, consisting of a magnetic quadrupole and a crossed optical dipole trap. In our setup we cross the phase transition with 2x10^6 atoms, and we obtain pure condensates of 5x10^5 atoms in the optical trap. This novel approach to cooling Helium-4 provides enhanced cycle stability, large optical access to the atoms and results in production of a condensate every 6 seconds - a factor 3 faster than the state-of-the-art. This speed-up will dramatically reduce the data acquisition time needed for the measurement of many particle correlations, made possible by the ability of metastable Helium to be detected individually.

cond-mat.quant-gas↗