Baptist Piest - Implementation of Delta-Kick squeezing in an atom interferometer

Atom interferometers are versatile devices to detect accelerations or rotations with high sensitivity and accuracy with important applications in geodesy, navigation and fundamental physics. The phase readout of light-pulse atom interferometers with classical input states is naturally limited by the quantum projection noise leading to the standard quantum limit. In this case, the sensitivity to accelerations is given by 1/(kT²Sqrt(N)) with the scale factor kT² and the atom number N. Increasing the sensitivity of atom interferometers is one of the main challenges in the field. Conducting experiments in long baseline facilities or microgravity can considerably increase the sensitivity. A different approach to further improve the performance of atom interferometers is given by circumventing the standard quantum limit using entangled states. This has successfully been demonstrated in recent experiments by the groups of J. Thomson [1] and C. Klempt [2]. These experiments made use of strong cavity-atom coupling in a high-finesse cavity and spin-collisions in a dipole trap, respectively.

In our experiment we strive to implement and analyze the recently proposed technique of Delta-Kick squeezing [3] and demonstrate an entanglement-enhanced gravimeter operating below shot noise. The entanglement is generated by the non-linear interatomic interactions of a focused Bose-Einstein condensate (BEC) of Rb-87 atoms which leads to momentum squeezing. The experiment is operated at LTE and has previously been used to investigate Casimir-Polder forces between Rb-87 atoms and a polished surface [4]. Since then, it is being prepared for the implementation of Delta-Kick squeezing. In this talk, I will discuss the experimental setup, the planned implementation of the entanglement-enhanced interferometer and show our recent progress.

[1] G. Greve et al. Nature 610, 472-477 (2022)
[2] C. Cassens et al. Phys. Rev. X 15, 011029 (2025)
[3] R. Corgier et al. Phys. Rev. Lett. 127, 183401 (2021)
[4] Y. Balland et al. Phys. Rev. Lett 133, 113403 (2024)