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A02 - Gravity sensing with very long baseline atom interferometry

Figure 01: Very Long Baseline Atom Interferometer
Figure 01: Very Long Baseline Atom Interferometer
Figure 02
Figure 02

Owing to the quadratic scaling of the leading order phase shift with increasing free evolution time, atom-interferometric gravimeters and gradiometers operating on baselines of several meters put acceleration resolution in the range of pm/s2 in reach. However, operating these devices with such high sensitivities is not only challenging concerning the production of ultracold atoms but also with respect to the design of the inertial reference and its careful isolation against perturbations from the outside, and the control of the environment along the baseline of the instrument.

By combining extended free evolution times of several seconds with large momentum transfer atomic beam splitters, very long baseline atom interferometers (VLBAIs; figure 01) promise to bring up the next generation of high-accuracy gravimetric base stations with sensitivities in the (nm/s2)/√Hz range as well as testbeds for gravity-gradiometry with unprecedented resolution. In addition, differential operation of two very long baseline atomic gravimeters with different species opens the way to quantum tests of the universality of free fall at the 10-13 level, competing with the current state-of- the-art classical tests (Hartwig et al., 2015) and providing means to surpass these in the future. Finally, macroscopically separated quantum superposition states provide a platform for novel tests of fundamental physics both at the interface between general relativity and quantum mechanics (Kovachy et al., 2015) and the transition between superposition states and macroscopism.

Operating atomic inertial sensors at the aforementioned sensitivity levels puts stringent constraints on the inertial reference. Owing to a low resonance frequency seismic attenuation system, we envisage a vibration-limited short-term sensitivity to accelerations of 10 (nm/s2)/√Hz with a factor of up to 25 improvement when correlating the interferometric signal with a classical inertial sensor in a hybrid setup (Figure 02).

Non-inertial signals can also couple in the interferometric signal via spurious forces on the atoms during their free evolution time, in particular due to magnetic field gradients. Precision measurements like tests of the universality of free-fall require for example magnetic field gradients below 1.5 nT/m along the 10 meters of the instrument‘s baseline. In addition, differential acceleration of the two atomic species during their free-fall is also impacted by gravity gradients that need to be known better than the 10-7 /s2 level.

In summary, owing to the employed atomic species choice and innovative source concepts as well as the seismic attenuation system and planned atom interferometer geometries, the VLBAI facility is an excellent and worldwide unique tool that will soon open completely new perspectives for geodesy and fundamental research.

Scientists working on this project

Dr. Naceur Gaaloul
email: gaalouliqo.uni-hannover.de

phone: +49 511 762-17455

Christian Meiners
email: meinersiqo.uni-hannover.de

phone: +49 511 762-19192

Dr. Dennis Schlippert
email: schlippertiqo.uni-hannover.de

phone: +49 511 762-2845

Dr. Christian Schubert
email: schubertiqo.uni-hannover.de

phone: +49 511 762-4107

Dorothee Tell
email: telliqo.uni-hannover.de

phone: +49 511 762-4107

Étienne Wodey
email: wodeyiqo.uni-hannover.de

phone: +49 511 762-4107

Selected Publications

Peer-Reviewed Literature

Abend S., Gebbe M., Gersemann M., Ahlers H., Müntinga H., Giese E., Gaaloul N., Schubert C., Lämmerzahl C., Ertmer W., Schleich W. P. and Rasel E. M. (2016): Atom-Chip Fountain Gravimeter, PRL 117, 203003
DOI: 10.1103/PhysRevLett.117.203003

Chamakhi R., Ahlers H., Telmini M., Schubert C., Rasel E.M. and Gaaloul N. (2015): Species-selective lattice launch for precision atom interferometry, New Journal of Physics Vol. 17, No. 12, p. 123002
DOI: 10.1088/1367-2630/17/12/123002

Hartwig J., Abend S., Schubert C., Schlippert D., Ahlers H., Posso-Trujillo K., Gaaloul N., Ertmer W. and Rasel E. M. (2015): Testing the universality of free fall with rubidium and ytterbium in a very large baseline atom interferometer, New J. Phys. 17, 035011 (2015)
DOI: 10.1088/1367-2630/17/3/035011
arXiv: 1503.01213

Non Peer-Reviewed Literature

Schlippert D., Albers H., Richardson L. L., Nath D., Heine H., Meiners C., Wodey É., Billon A., Hartwig J., Schubert C., Gaaloul N., Ertmer W. and Rasel E. M. (2016): Ground Tests of Einstein's Equivalence Principle: From Lab-based to 10-m Atomic Fountains, Proceedings of the 50th Rencontres de Moriond ”Gravitation: 100 years after GR”, La Thuile (Italy), 21-28 March
arXiv: 1507.05820

Presentations, Talks and Posters

Schlippert D. (2015): Gravity sensing with VLBAI, EGU 2015


Kovachy T., Asenbaum P., Overstreet C., Donnelly C. A., Dickerson S. M., Sugarbaker A., Hogan J. M. and Kasevich M. A.  (2015): Quantum superposition at the half-metre scale, Nature 528, 530-533
DOI: 10.1038/nature16155