Large area atomtronic Sagnac interferometry

We present an atomtronic Sagnac interferometer using Rubidium87 Bose-Einstein condensates (BEC) in an optical waveguide. The interferometer is based on a moving, linear, optical waveguide containing BECs, and the coherent manipulation of the atomic states is performed by standing wave light-pulses to implement beam-splitters and mirrors. This work is an extension of the study presented in a recent article from our group (arXiv:2201.12461). To further increase the Sagnac area and thus the sensitivity of the device to rotation, we addressed two main issues. First, to overcome the problem of wave-packet expansion in the waveguide for long interrogation times, we improved the implementation of the delta-kick cooling technique, to first expand and then collimate the BECs. The large wave-packet size corresponds to lower atomic density and reduces the undesired effect of interaction between atoms. The second important challenge was the vibration of the retro-reflecting mirror that creates the standing wave. This has been addressed by correcting the light phase using a mechanical accelerometer. Along with the above-mentioned improvements, I will describe results demonstrating Sagnac area of 3.8 sq. mm in a linear waveguide configuration.