Probing the Local Rapidity Distribution of a One-Dimensional 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.

Relaxation of Phonons in the Lieb-Liniger Gas by Dynamical Refermionization.

Motivated by recent experiments, we investigate the Lieb-Liniger gas initially prepared in an out-of-equilibrium state that is Gaussian in terms of the phonons, namely whose density matrix is the exponential of an operator quadratic in terms of phonon creation and annihilation operators. Because the phonons are not exact eigenstates of the Hamiltonian, the gas relaxes to a stationary state at very long times whose phonon population is a priori different from the initial one. Thanks to integrability, that stationary state needs not be a thermal state.

Givosiran in acute intermittent porphyria: A personalized medicine approach.

Background: In patients with acute intermittent porphyria (AIP), induction of delta aminolevulinic acid synthase 1 (ALAS1) leads to haem precursor accumulation that may cause recurring acute attacks. In a recent phase III trial, givosiran significantly reduced the attack rate in severe AIP patients. Frequent adverse events were injection-site reaction, fatigue, nausea, chronic kidney disease and increased alanine aminotransferase.

Breakdown of Tan's Relation in Lossy One-Dimensional Bose Gases.

In quantum gases with contact repulsion, the distribution of momenta of the atoms typically decays as ∼1/|p|^{4} at large momentum p. Tan's relation connects the amplitude of that 1/|p|^{4} tail to the adiabatic derivative of the energy with respect to the coupling constant or scattering length of the gas. Here it is shown that the relation breaks down in the one-dimensional Bose gas with contact repulsion, for a peculiar class of stationary states.

Generalized Hydrodynamics on an Atom Chip.

The emergence of a special type of fluidlike behavior at large scales in one-dimensional (1D) quantum integrable systems, theoretically predicted in O. A. Castro-Alvaredo et al.

Cooling a Bose Gas by Three-Body Losses.

We report the demonstration of cooling by three-body losses in a Bose gas. We use a harmonically confined one-dimensional (1D) Bose gas in the quasicondensate regime and, as the atom number decreases under the effect of three-body losses, the temperature T drops up to a factor of 4. The ratio k_{B}T/(mc^{2}) stays close to 0.

Erratum: Quench-Induced Breathing Mode of One-Dimensional Bose Gases [Phys. Rev. Lett. 113, 035301 (2014)].

This corrects the article DOI: 10.1103/PhysRevLett.113.

Momentum-Space Correlations of a One-Dimensional Bose Gas.

Analyzing the noise in the momentum profiles of single realizations of one-dimensional Bose gases, we present the experimental measurement of the full momentum-space density correlations ⟨δn_{p}δn_{p^{'}}⟩, which are related to the two-body momentum correlation function. Our data span the weakly interacting region of the phase diagram, going from the ideal Bose gas regime to the quasicondensate regime. We show experimentally that the bunching phenomenon, which manifests itself as super-Poissonian local fluctuations in momentum space, is present in all regimes.

Quench-induced breathing mode of one-dimensional Bose gases.

We measure the position- and momentum-space breathing dynamics of trapped one-dimensional Bose gases at finite temperature. The profile in real space reveals sinusoidal width oscillations whose frequency varies continuously through the quasicondensate to ideal Bose gas crossover. A comparison with theoretical models taking temperature into account is provided.

Sub-Poissonian fluctuations in a 1D Bose gas: from the quantum quasicondensate to the strongly interacting regime.

We report on local, in situ measurements of atom number fluctuations in slices of a one-dimensional Bose gas on an atom chip setup. By using current modulation techniques to prevent cloud fragmentation, we are able to probe the crossover from weak to strong interactions. For weak interactions, fluctuations go continuously from super- to sub-Poissonian as the density is increased, which is a signature of the transition between the subregimes where the two-body correlation function is dominated, respectively, by thermal and quantum contributions.

Probing three-body correlations in a quantum gas using the measurement of the third moment of density fluctuations.

We perform measurements of the third moment of atom number fluctuations in small slices of a very elongated weakly interacting degenerate Bose gas. We find a positive skewness of the atom number distribution in the ideal gas regime and a reduced skewness compatible with zero in the quasicondensate regime. For our parameters, the third moment is a thermodynamic quantity whose measurement constitutes a sensitive test of the equation of state, and our results are in agreement with a modified Yang-Yang thermodynamic prediction.

Roughness suppression via rapid current modulation on an Atom chip.

We present a method to suppress the roughness of the potential of a wire-based, magnetic atom guide: modulating the wire current at a few tens of kHz, the potential roughness, which is proportional to the wire current, averages to zero. Using ultracold 87Rb clouds, we show experimentally that modulation reduces the roughness by at least a factor five without measurable heating or atom loss. This roughness suppression results in a dramatic reduction of the damping of center-of-mass oscillations.

Experimental evidence for the breakdown of a Hartree-Fock approach in a weakly interacting Bose gas.

We investigate the physics underlying the presence of a quasicondensate in a nearly one dimensional, weakly interacting trapped atomic Bose gas. We show that a Hartree-Fock (mean-field) approach fails to predict the existence of the quasicondensate in the center of the cloud: the quasicondensate is generated by interaction-induced correlations between atoms and not by a saturation of the excited states. Numerical calculations based on Bogoliubov theory give an estimate of the crossover density in agreement with experimental results.

Observations of density fluctuations in an elongated Bose gas: ideal gas and quasicondensate regimes.

We report in situ measurements of density fluctuations in a quasi-one-dimensional 87Rb Bose gas at thermal equilibrium in an elongated harmonic trap. We observe an excess of fluctuations compared to the shot-noise level expected for uncorrelated atoms. At low atomic density, the measured excess is in good agreement with the expected "bunching" for an ideal Bose gas.

[Acute changes in load: effects of myocardial velocities measured by doppler tissue imaging].

The value of measuring the velocities of myocardial motion in the analysis of regional contractility has been demonstrated. The effects of changes in load on myocardial velocities has not been extensively studied. The aim of this study was to increase the change in myocardial velocities during haemodialysis.