The estimation of the orientation an object, and a human head in particular, can be defined by Euler angles: yaw, pitch roll. robust drift-free those angles is usually achieved with data from several sensors such as accelerometers, gyroscopes magnetometers, processed sensor fusion algorithms. However, wearable devices hearing instruments are rarely equipped all sensors, might only have single a...

We report a metrology scheme which measures magnetic susceptibility of an atomic spin ensemble along the $x$ and $z$ direction produces parameter estimation with precision beating standard quantum limit. The is initialized via one-axis squeezing optimized time $\phi$ to be estimated assumed as uniformly distributed between 0 $2\pi$. One can produced every two data measured axis respectively, ha...