Quantum gas mixtures and dual-species atom interferometry in space.

The capability to reach ultracold atomic temperatures in compact instruments has recently been extended into space1,2. Ultracold temperatures amplify quantum effects, whereas free fall allows further cooling and longer interactions time with gravity-the final force without a quantum description. On Earth, these devices have produced macroscopic quantum phenomena such as Bose-Einstein condensates (BECs), superfluidity, and strongly interacting quantum gases3. Terrestrial quantum sensors interfering the superposition of two ultracold atomic isotopes have tested the universality of free fall (UFF), a core tenet of Einstein's classical gravitational theory, at the 10-12 level4. In space, cooling the elements needed to explore the rich physics of strong interactions or perform quantum tests of the UFF has remained elusive. Here, using upgraded hardware of the multiuser Cold Atom Lab (CAL) instrument aboard the International Space Station (ISS), we report, to our knowledge, the first simultaneous production of a dual-species BEC in space (formed from 87Rb and 41K), observation of interspecies interactions, as well as the production of 39K ultracold gases. Operating a single laser at a 'magic wavelength' at which Rabi rates of simultaneously applied Bragg pulses are equal, we have further achieved the first spaceborne demonstration of simultaneous atom interferometry with two atomic species (87Rb and 41K). These results are an important step towards quantum tests of UFF in space and will allow scientists to investigate aspects of few-body physics, quantum chemistry and fundamental physics in new regimes without the perturbing asymmetry of gravity.

Pathfinder experiments with atom interferometry in the Cold Atom Lab onboard the International Space Station.

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.

Temperature stability of a dichroic atomic vapor laser lock.

We have investigated the temperature stability of the dichroic atomic vapor laser lock laser frequency lock method. We find that, in general, the lock exhibits significant temperature sensitivity, leading to laser frequency drifts as large as tens of MHz/K. However, for certain configurations of the optical elements of the system, this temperature dependence is reduced to below 1 MHz/K. These temperature-independent points can be found across a broad range of frequencies. We present a numerical model that reproduces the general behavior of the system.