A Quantum Test of Einstein's Equivalence Principle
QUEST task group 2’s ("Quantum Test of the Equivalence Principle") objective is to test the universality of free fall of 87Rb and 39K atoms by means of matter-wave interferometry. Recently, within the scope of this project a stability of ~10-8 g, g being earth’s acceleration, using a 87Rb absolute gravimeter has been demonstrated. At the moment, the existing setup is being upgraded with the second species, 39K, and first ensembles of ~107 atoms could be trapped. Operating as a dual species matter wave interferometer the apparatus will be able to test Einstein’s equivalence principle, yielding a precision of ~10-9 g after some hours of integration. In order to cope with systematics, an optical dipole trap at a wavelength of 2µm is available. Earlier, the first Bose-Einstein condensate (BEC) at this wavelength was realized with this setup [Zaiser et al., Phys. Rev. A 83, 035601 (2011)].
Research goals
- Quantum test of Einstein's equivalence principle
- Pulsed source of (ultra)cold atomic ensembles
Current status
Recent results
During Christmas 2011 we were able to observe first tidal signals. By now, a short term stability of 4.2x10-6 m/s2/Hz1/2 and 3.86x10-8 m/s2 @ 49152s integration have been demonstrated. Since our short term stability is solely limited by envirenmontal vibrational noise, we have recently started implementing a post-correcting algorithm based on the use of a high bandwidth classical accelerometer.
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