Application Of Magnetic Field Modulation In Potassium Atomic Magnetometer

Atomic magnetometers are magnetic-field-measuring devices using atomic Zeeman effect,which involve the manipulation of atomic spin states.Magnetic modulation is a commonly used technique for manipulating atomic spin states,and it can be used to suppress the low frequency noises of mangetometers and to search novel operational modes.A typical magnetic-resonance magnetometry scheme employs a static bias magnetic field and an orthogonal driving magnetic field oscillating at the Larmor frequency,at which the atomic polarization precesses around the static magnetic field.In this thesis,we focus on the variations of the resonance condition and the spin precession dynamics resulting from the parametric modulation of the bias field,and the potential applications of this modulation scheme.With the help of perturbation analysis based on Bloch equations,it is shown that the driving magnetic field with the frequency detuned by different harmonics of the parametric modulation frequency can lead to resonance as well.Also,a series of frequency sidebands centered at the driving frequency and spaced by the parametric modulation frequency can be observed in the precession of the atomic polarization,and the resonant amplitudes of those sidebands can be controlled by varying the ratio between the amplitude and the frequency of the parametric modulation.The above effects are demonstrated in a potassium vapor cell,and the experimental results are in well agreement with theoretical predictions.These effects have many potential applications,including frequency shift of measured signals in magnetometers,vector-mode operation and frequency-response calibration of magnetic coils.