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Logo: Institut für Quantenoptik/Leibniz Universität Hannover
Logo Leibniz Universität Hannover
Logo: Institut für Quantenoptik/Leibniz Universität Hannover
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Quantum Test of Einstein's Equivalence Principle

By allowing a violation of the universality of free fall, certain theoretical scenarios reconcile the two major theories of modern physics, general relativity and quantum mechanics, which are currently inconsistent. The universality of free fall, a corner stone of Einstein's general relativity, states: that two bodies will drop at the same rate in a given gravitational field. Our objective is to test this by means of matter wave interferometry. We exploit the wave nature of 87Rb and 39K atoms and, by their interference, measure the gravitational acceleration.

We have demonstrated the first inertial sensitive interferometer using 39K with pulse separation times of up to T=25ms and realized a rubidium gravimeter (T=60ms) with a short term stability of 4.2x10-6 m/s2/Hz1/2 and a resolution of 3.86x10-8 m/s2 @ 49152s integration.

Research goals

  • Quantum test of Einstein's equivalence principle
  • Studies of optical traps as sources for precision matter wave interferometry

    • Pulsed source of (ultra)cold atomic ensembles

Current status

Recently, we we were able to perform the first quantum test of the universality of free fall ([Schlippert et al., Phys. Rev. Lett. 112, 203002 (2014)]) using two different atomic species yielding an Eötvös ratio of (0.3±5.4)x10-7. In order to mitigate systematic effects, we plan to employ an optical dipole trap at a wavelength of 2µm ([Zaiser et al., Phys. Rev. A 83, 035601 (2011)]) in the future.  In addition, since our short term stability is solely limited by environmental vibrational noise, we are investigating correlation of classical high-bandwidth seimsmometers/accelerometers for post-correction algorithms in order to overcome the current stability limitation.

Extension of dual-species measurements to pulse separation times of up to T=100ms are currently underway.



Potassium Mach-Zehnder fringes (T=25ms).
Long-term data recorded with the rubidium gravimeter (T=60ms).