Towards the Non-Zero Field Cesium Magnetic Sensor Array for Magnetoencephalography

Magnetic sensors developed for application in magnetoencephalography must meet a number of requirements; the main ones are compactness, sensitivity and response speed. We present a quantum optically pumped atomic sensor with cell volume of 0.5 cm(3) that meets these requirements and is operable in nonzero magnetic fields. The ultimate sensitivity of the sensor was estimated as (using the criteria of the ratio of the slope of the magnetic resonance signal to the shot noise spectral density) to be better than 5 fT/root Hz. The actual sensitivity, measured in a gradiometric scheme, reaches 13 fT/root Hz per sensor. We also present a novel and fast algorithm for optimization of the geometric properties of non-zero field sensor array with respect to maximization of the information transfer rate for cortical sources.

Automated summary

A quantum optically pumped atomic sensor with a cell volume of 0.5 cm(3) is presented in this study to meet the requirements of compactness, sensitivity, and response speed for magnetoencephalography applications in nonzero magnetic fields. The estimated ultimate sensitivity of the sensor is better than 5 fT/root Hz, while the actual sensitivity reaches 13 fT/root Hz per sensor in a gradiometric scheme. Additionally, a novel and fast algorithm for optimizing the geometric properties of the sensor array in nonzero magnetic fields is introduced to maximize the information transfer rate for cortical sources.