Towards the non-zero field cesium magnetic sensor array for
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 0.5cm3 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/Hz1/2.
The actual sensitivity, measured in a gradiometric scheme, reaches 13
fT/Hz1/2 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.