Research On Precise Measurement Of Microwave Electric Fields And Van Der Waals Forces Based On Electromagnetically Induced Transparency

Electromagnetically induced transparency(EIT)is a quantum interference effect,opening up a new path for quantum sensing.When the external control field interacts with the medium,the absorption of the probe field changes within a certain frequency range,and the transmittance is increased or even completely transparent.The susceptibility at the transparent window changes abruptly,and the medium changes from the original normal dispersion to the anomalous dispersion.Slow light effect,optical storage,optical light opening,single photon source preparation,and microwave electric field measurement have been achieved based on EIT effect.Recently,Microwave electric field measurement based on Rydberg atoms has aroused great interest among researchers.Rydberg atoms are a class of atoms in highly excited states.They have the advantages of long lifetime,high susceptibility,large transition dipole moment and low ionization threshold field,and are sensitive to external electromagnetic fields,which can be used to measurement microwave electric field.Rydberg atomic sensors are mostly based on the single dark state system.Its measurement accuracy and sensitivity are limited.This dissertation discusses how to use the electromagnetic induction transparency principle to achieve precise measurement of microwave electric field and van der Waals force,and the innovative results are as follows:1.This dissertation proposes a method of enhancing the measurement of the microwave electric field with interacting dark interaction.The five-level Rydberg atomic system has two electromagnetically induced transparency(EIT)subsystems.Two sharp peaks are located in the center of EIT window when microwave is applied.It is found that the frequency splitting of two central peaks is linearly to the applied microwave field,which can be used to probe the microwave electric field strength.Interacting dark resonances much narrow the linewith of linear and nonlinear absorption spectrums,which could greatly improve the probe sensitivity and accuracy.Moreover,increasing the ratios of two coupling fields can enhance the probe sensitivity substantially.The simulation results show that the measurement sensitivity is one order of magnitude larger than that of the common four-level single-dark-state system.The measurement accuracy could be improved by more than three orders of magnitude compared with the single-dark-state system.The above results can be well understood with the aid of the dressed-state theory.2.Besides,this article presents a method of measuring the van der Waals interaction of cold Rydberg atoms based on EIT.In the mean field approximation,we examine the influence of the van der Waals interaction on the EIT spectrum.It is interesting to find that the van der Waals interaction strength is proportional to frequency shifts of the transmission spectrum.This can be used to probe the van der Waals interaction strength.The paper discuss the evolution of the van der Waals interaction by adopting the model of the cubic lattice.It is found that the van der Waals interaction strength raises as the coupling field strength.Also.The simulation results show that the total blockade appears in dense gases under the condition of the strong coupling,which brings some difficult to the vdW measurement.In addition,the paper discuss the boundary conditions of total blockade and explain the evolution of van der Waals interaction.Relevant research has potential applications in preparation of single photon sources.