Nuclear spin gyroscope based on an atomic comagnetometer

We describe a new nuclear spin gyroscope based on K-³He comagnetometer. In this type of Gyroscope, there is much space in improving the sensitivity of measurement, therefore, it´s significant to study it. In the comagnetometer, the state equation of the system is very complicated, and we just give the relationship between comagnetometer signal and the rotation angle of gyroscpoe in Bloch picture. Finally, we extend the equation of system to quantum filtering equation, so that we could improve the stability of system and sensitivity of measurement by continuous measurement and quantum feedback control.