Ground Tests of Einstein's Equivalence Principle: From Lab-based to 10-m Atomic Fountains

Abstract

To date, no framework combining quantum field theory and general relativity and hence unifying all four fundamental interactions, exists. Violations of the Einstein's equivalence principle (EEP), being the foundation of general relativity, may hold the key to a theory of quantum gravity. The universality of free fall (UFF), which is one of the three pillars of the EEP, has been extensively tested with classical bodies. Quantum tests of the UFF, e.g. by exploiting matter wave interferometry, allow for complementary sets of test masses, orders of magnitude larger test mass coherence lengths and investigation of spin-gravity coupling. We review our recent work towards highly sensitive matter wave tests of the UFF on ground. In this scope, the first quantum test of the UFF utilizing two different chemical elements, Rb-87 and K-39, yielding an Eötvös ratio ${\eta }_{\text{Rb,K}}=(0.3\pm 5.4)\times 10^{-7}$ has been performed. We assess systematic effects currently limiting the measurement at a level of parts in $10^8$ and finally present our strategies to improve the current state-of-the-art with a test comparing the free fall of rubidium and ytterbium in a very long baseline atom interferometry setup. Here, a 10 m baseline combined with a precise control of systematic effects will enable a determination of the Eötvös ratio at a level of parts in $10^{13}$ and beyond, thus reaching and overcoming the performance limit of the best classical tests.

Proceedings of the 50th Rencontres de Moriond "Gravitation: 100 years after GR", La Thuile (Italy), 21-28 March 2015

References in corpus (13)

• The Confrontation between General Relativity and Experiment
• Test of the Equivalence Principle Using a Rotating Torsion Balance
• Interferometry with Bose-Einstein Condensates in Microgravity
• Quantum Test of the Universality of Free Fall
• Atom-interferometry constraints on dark energy
• Test of Equivalence Principle at $10^{-8}$ Level by a Dual-species Double-diffraction Raman Atom Interferometer
• Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects
• Matter wave lensing to picokelvin temperatures
• Testing the universality of free fall with rubidium and ytterbium in a very large baseline atom interferometer
• Atom interferometry in an optical cavity
• Precision Measurement of Transition Matrix Elements via Light Shift Cancellation
• Light-pulse atom interferometry
• Differential atom interferometry with ${}^{87}$Rb and ${}^{85}$Rb for testing the UFF in STE-QUEST

Cited by in corpus (2)

• Attractive force on atoms due to blackbody radiation
• Controlling the Multiport Nature of Bragg Diffraction in Atom Interferometry