Project B09: Quantum clock interferometry

Introduction

Our experimental approach utilises the generation of all-optical ytterbium Bose-Einstein condensates and beam splitters at 1156 nm for driving the clock transition ¹S₀ → ³P₀. Here, a two-photon E1-M1 excitation process avoids transferring recoil and magic Bragg beam splitters at 759 nm or Bragg beam splitters at 399 nm are employed for transferring momentum. The beam splitting for delocalisation is based on a combination of sequential or higher-order Bragg pulses and Bloch oscillations. Initially, the project will finalise the studies of the different possible interferometer configurations in a small baseline to identify suitable parameters for operation, e.g. beam splitter pulse duration and intensity, and to characterise spurious phase shifts, e.g. lights shifts. In a second step, the ytterbium source will be integrated into the Very Long Baseline Atom Interferometry facility to enable extended times of free fall of 1s to 2s. Here, we target to resolve the gravitationally induced red shift down to the level of ten percent after averaging. This will mark the first measurement of gravitational red shift in an atom interferometer and consequently validate the theoretical description, laying the grounds for future precision measurements of gravitational red shift by means of atom interferometry.