Research On A High-sensitivity Faraday Magnetometer Based On Cavity Electromagnetic Induction Transparency

Weak magnetic detection is of extremely important research value,and advanced measurement methods of detecting magnetic field and high-performance magnetic field sensors have always been a hot research topic all over the world.Magnetometer based on EIT utilizes the higher dispersion at an EIT resonance point where the absorption is almost completely canceled by quantum interference.Thus,contrary to the common high-density and strong-coupling regime,it could reduce the signal-to-noise ratios.In recent years,the result of the development of cavity quantum electrodynamics,EIT with ultra narrow line width and a large dispersion is found in multi-level atom-cavity system.The paper mainly studies weak magnetic field detection based on Faraday rotation with intracavity electromagnetically induced transparency.It mainly is divided into four parts:Firstly,we briefly introduced the cavity quantum electrodynamics and its research progress in microwave and optical frequency area.Then,we mainly describe frequency pulling effect of multi-level cavity-atom system,EIT with single atoms in a cavity and vacuum induced transparency,and describe the application of cavity EIT in cavity linewidth narrowing,photon-number selective group delay and light control light,and so on.Finally,we describe the significance of weak magnetic detection and different magnetic detection methods of different principle.The second chapter,we focuses our attention on the theory basis related to the paper.we describle the Hamiltonian in the dipole approximation,the rotating wave approximation,input-out relationg of cavity and interaction of a two-level atom with a single cavity mode field.In addition to,we also describe the Heisenberg equation and probability amplitude two of method.The third part is the heart content of this thesis,we mainly investigate high sensitivity Faraday magnetometry based on intracavity EIT of four-level tripod configuration atomic system.We apply a linear polarized probe field to couple into the cavity,and analyze the transmissions of its left-and right-circular polarizedcomponents based on intracavity EIT.Our study show that the cavity-enhanced Faraday rotation supports the detection of weak magnetic field,with high sensitivity.For single probe photon measurement,the sensitivity is 0.7(5)nT(?),inversely proportional to thenumber of atoms.With multiphoton measurement,the limit of sensitivity can be improved to 4.7(9)fT(?),proportional to the input power.The finally is the full text of the summary and expectation to high sensitivity Faraday magnetometry based on intracavity EIT.