Decoherence induced by stochastic noise in matter-wave interferometers for gravity experiments
Robustness is a critical challenge for matter-wave interferometers. In real experiments, various sources of classical noises arise from mechanical vibrations, seismic motions, inertial forces, tidal forces, magnetic field fluctuations and so on. These noises can disturb the spin and spatial degrees of freedom of the test mass, resulting in witness loss of the interferometer. While spin decoherence is relatively well understood and can be formulated by the Bloch-Redfield master equation, the impact on spatial degrees of freedom still requires systematic investigation.
In his thesis, Mengzhi Wu therefore aims to explore witness loss in an SGI induced by stochastic noises acting on spatial degrees of freedom. Wu concludes that the witness gets lost via several mechanisms: (i) Dephasing, (ii) the Humpty-Dumpty problem and (iii) Position localization decoherence.
Wu furthermore analyses several representative noise sources: (i) Gravitational and electrostatic noise, (ii) Inertial acceleration noise and (iii) Inertial torsion noise.
Taken together, these analyses build a comprehensive picture of how stochastic noise affects the spatial dynamics of an SGI and leads to the loss of spin-based witnesses. Future work may include more realistic noise sources such as magnetic noise and trap-potential noise. These insights will be valuable for future experimental implementations, particularly in precision sensing for quantum gravity, where preserving coherence and maintaining reliable witness signals are essential.