Atomic source selection in space-borne gravitational wave detection

Abstract

Recent proposals for space-borne gravitational wave detectors based on atom interferometry rely on extremely narrow single-photon transition lines as featured by alkaline-earth metals or atomic species with similar electronic configuration. Despite their similarity, these species differ in key parameters such as abundance of isotopes, atomic flux, density and temperature regimes, achievable expansion rates, density limitations set by interactions, as well as technological and operational requirements. In this study, we compare viable candidates for gravitational wave detection with atom interferometry, contrast the most promising atomic species, identify the relevant technological milestones and investigate potential source concepts towards a future gravitational wave detector in space.

Concept study and preliminary design of a cold atom interferometer for space gravity gradiometry

“…For the gyrometer, we considered a white noise of 6.8 £ 10°6 rad/s/ p H z, as guaranteed by the constructor. For the star-trackers, we assumed that the noise PSD follows the model derived by Stummer et al [36] for the y-component of the angular velocity. Both spectra are plotted in Figure 3.2 along with the example of the spectrum of a combined solution.…”

Inertial sensing with quantum gases: a comparative performance study of condensed versus thermal sources for atom interferometry

“…These are regimetypical parameters for experiments with either thermal ensembles or BECs [4,9,10]. Following [4], the expansion energies for the thermal atoms and the chemical Fig. 1 Size evolution of thermal ensembles (red) and BECs (blue) after release from a trap.…”

“…Proposals for space missions, in particular, rely on Delta-Kick collimation (DKC) via optical or magnetic potentials to exploit extended times of free fall in microgravity [7][8][9][10] and achieve extremely low wave packet a e-mail: gaaloul@iqo.uni-hannover.de (corresponding author) expansion rates, corresponding to pK temperatures in thermal ensembles. Bose-Einstein condensed (BEC) ensembles are better suited for DKC aiming at long interrogation times [4], but suffer from a reduced atomic flux due to the evaporation despite recent promising studies [11]. Molasses-cooled atoms feature a higher number of atoms, but are typically velocity-filtered in 1D [12], which ultimately implies a lower flux of atoms as we will detail in our study.…”

“…At the same time, the characterization of errors requires an increased level of control over the manipulation and preparation of atoms. Limitations of interferometers operating with molasses-cooled atoms and their mitigation by reducing the residual expansion rates were studied theoretically [4] and experimentally [5,6].…”

Matter-Wave Interferometry for Inertial Sensing and Tests of Fundamental Physics

“…12 Making use of hybrid magnetic and optical trapping techniques as well as delta-kick collimation, 17 we anticipate an atom flux on the order of 10 6 at/s with temperatures in the picokelvin regime. 18 (3) For absolute measurements, we will utilize a seismic attenuation system (SAS) to suspend a retro reflection mirror that serves as the atom interferometer's inertial reference. Based on geometric anti-springs, 19…”