Eric Charron

Experiments with ultracold quantum gases are a rapidly advancing research field with many applications in fundamental physics and quantum technology. Here, we report on a high-flux generation of Bose-Einstein condensate mixtures of ⁴¹ K and ⁸⁷ Rb, using a fully integrated sounding rocket setup. We compare the release and the free expansion of the quantum mixtures obtained with the apparatus placed on ground or in free fall in an Einstein-Elevator. The release dynamics are governed by the intra- and interspecies interactions as well as the decaying magnetic field during the release. The latter can be minimized by a dedicated switch-off protocol of the trap generating currents where an exact model enabled us to characterize the interaction effects. Our results establish a new benchmark for generating ultracold mixtures on mobile platforms, with direct relevance for future experiments on interacting quantum gases and tests of the equivalence principle in space.

Atom interferometers deployed in space are excellent tools for high precision measurements, navigation, or Earth observation. In particular, differential interferometric setups feature common-mode noise suppression and enable reliable measurements in the presence of ambient platform noise. Here we report on orbital magnetometry campaigns performed with differential single- and double-loop interferometers in NASA’s Cold Atom Lab aboard the International Space Station. By comparing measurements with atoms in magnetically sensitive and insensitive states, we have realized atomic magnetometers mapping magnetic field curvatures. Our results pave the way towards precision quantum sensing missions in space.

We present a detailed numerical study of a protocol for momentum-selective transport of a Bose–Einstein condensate in a one-dimensional optical lattice, achieving narrow momentum distributions through controlled nonadiabatic dynamics. The protocol consists of nonadiabatic loading into the lattice, coherent acceleration using a symmetric trapezoidal acceleration profile, and nonadiabatic release into free space. Using the time-dependent Gross–Pitaevskii equation, we simulate the full sequence and analyze the role of nonadiabatic excitations on the final momentum distribution. We identify the intrasite breathing dynamics as the dominant mechanism governing spectral purity under fast loading conditions. By tracking the condensate's spatial width during the evolution, we demonstrate a direct correlation with the final momentum spread. A variational model based on a Gaussian ansatz quantitatively reproduces the observed dynamics and provides physical insight into the breathing mechanism. Our results reveal the existence of “magic” times, i.e., specific loading or acceleration durations synchronized with the breathing oscillation period, where quasimonochromatic momentum distributions can be achieved even with loading times as short as 100 μs. In the tight-binding regime, this approach offers speedup factors of 3 to 6 compared to adiabatic protocols while maintaining high transfer fidelities, providing a practical route to coherent transport for quantum sensors operating under stringent timing constraints.

We present a theoretical study of delta-kick collimation (DKC) applied to heteronuclear Feshbach molecules, focusing on both condensed and thermal ensembles across various interaction and temperature regimes. We demonstrate that DKC enables significant reductions in molecular cloud expansion energies and beam divergence, achieving expansion energies in the picokelvin range, comparable to state-of-the-art results obtained experimentally with atoms. Furthermore, we show that vibrational and translational motions remain strongly decoupled throughout the process, and that the vibrational energy remains well below the molecular binding energy, thereby ensuring molecular stability during the delta kick. This work paves the way for advanced experimental sequences involving degenerate ground-state molecules, light-pulse molecular interferometry, and applications of dual-species precision measurements, such as testing the universality of free fall.

We present a method utilizing atomic diffraction patterns and statistical analysis tools to infer the Casimir-Polder interaction between argon atoms and a silicon nitride nanograting. The quantum model that supports the data is investigated in detail, as are the roles of nanograting geometry, finite-size effects, slit width opening angles, Lennard-Jones potentials, and patch potentials. Our findings indicate that the atom-surface potential strength parameter is C 3 = 6.9 ± 1.2 meV nm 3 . This value is primarily constrained by the knowledge of the nanograting geometry. The high sensitivity of our method paves the way for precise determination of the Casimir-Polder potential and exploration of new short-distance forces.

Deployment of ultracold atom interferometers (AI) into space will capitalize on quantum advantages and the extended freefall of persistent microgravity to provide high-precision measurement capabilities for gravitational, Earth, and planetary sciences, and to enable searches for subtle forces signifying physics beyond General Relativity and the Standard Model. NASA’s Cold Atom Lab (CAL) operates onboard the International Space Station as a multi-user facility for fundamental studies of ultracold atoms and to mature space-based quantum technologies. We report on pathfinding experiments utilizing ultracold ⁸⁷Rb atoms in the CAL AI. A three-pulse Mach–Zehnder interferometer was studied to understand the influence of ISS vibrations. Additionally, Ramsey shear-wave interferometry was used to manifest interference patterns in a single run that were observable for over 150 ms free-expansion time. Finally, the CAL AI was used to remotely measure the Bragg laser photon recoil as a demonstration of the first quantum sensor using matter-wave interferometry in space.

We present a theoretical model of matter-wave diffraction through a material nanostructure. This model is based on the numerical solution of the time-dependent Schrödinger equation, which goes beyond the standard semiclassical approach. In particular, we consider the dispersion force interaction between the atoms and the material, which is responsible for high energy variations. The effect of such forces on the quantum model is investigated, along with a comparison with the semiclassical model. In particular, for atoms at low velocity and close to the material surface, the semiclassical approach fails, while the quantum model accurately describes the expected diffraction pattern. This description is thus relevant for slow and cold atom experiments where increased precision is required, e.g., for metrological applications. Published by the American Physical Society 2024

The sensitivity of atom interferometers depends on their ability to realize long pulse separation times and prevent loss of contrast by limiting the expansion of the atomic ensemble within the interferometer beam through matter-wave collimation. Here we investigate the impact of atomic interactions on collimation by applying a lensing protocol to a ³⁹K Bose-Einstein condensate at different scattering lengths. Tailoring interactions, we measure energies corresponding to (340 ± 12) pK in one direction. Our results are supported by an accurate simulation, which allows us to extrapolate a 2D ballistic expansion energy of (438 ± 77) pK. Based on our findings we propose an advanced scenario, which enables 3D expansion energies below 16 pK by implementing an additional pulsed delta-kick. Our results pave the way to realize ensembles with more than 1 × 10⁵ atoms and 3D energies in the two-digit pK range in typical dipole trap setups without the need for micro-gravity or long baseline environments.

We present an efficient method for modeling the single and double ionization dynamics of the H₂ molecule in ultrashort, intense laser fields. This method is based on a semianalytical approach to calculate the time-dependent single and double molecular ionization rates and on a numerical approach to describe the vibrational motion that takes place in the intermediate molecular ion H₂⁺. This model allows for the prediction of the single and double ionization probabilities of the H₂ molecule to be made over a wide range of frequencies and laser intensities with limited computational time while providing a realistic estimate of the energy of the products of the dissociative ionization and of the Coulomb explosion of the H₂ molecule. The effect of vibrational dynamics on ionization yields and proton kinetic energy release spectra is demonstrated and, in the case of the latter, is discussed in terms of basic strong-field molecular fragmentation mechanisms.