Magnetic shield provides field stability for ultracold atomic gas experiments

Atomic transitions are dependent on the magnetic field, so suppressing magnetic noise is crucial to creating a good environment in which to run experiments – particularly experiments on ultracold atomic gases. These experiments use atom interferometry such as gravimeters, gradiometers and gyroscopes, and having a stable magnetic field is necessary to perform long timescale measurements to a high level of precision.

Farolfi et al. designed a compact magnetic shield which reduces low-frequency magnetic field noise by more than 5 orders of magnitude. Taking into consideration experimental constraints and available materials for magnetic shielding, the researchers created the optimal design for external magnetic field noise attenuation during atomic gas experiments.

“What is unprecedented in our work is the simultaneous presence of high attenuation of environmental fields, large optical access allowing for laser cooling and manipulation of the atomic sample, and compatibility of the screened environment with the application of the magnetic fields typically required for the production of ultracold atomic samples,” said author Arturo Farolfi.

To optimize the performance of their shield, the team designed it to be cylindrical and multi-layered, according to the ideal geometric shape for magnetic shielding. The shield can then be mounted around a vacuum cell containing the atomic gas under investigation. Performance experiments confirmed the shield creates a stable magnetic field over a long period of time.

“In the future, we will take advantage of the magnetic field stability to study coherently-coupled Bose-Einstein condensates in atomic states highly sensitive to the magnetic field,” said Farolfi. “Long coherence times will make it possible to observe quantum many-body effects that have been, until now, only numerically simulated.”

Source: “Design and characterisation of a compact magnetic shield for ultracold atomic gas experiments,” by A. Farolfi, D. Trypogeorgos, G. Colzi, E. Fava, G. Lamporesi, and G. Ferrari, Review of Scientific Instruments (2019). The article can be accessed at https://doi.org/10.1063/1.5119915 .