Rydberg Electromagnetically Induced Transparency And According Application

Electromagnetically induced transparency?EIT?is a special kind of nonlinear effectby interaction between lasers and matter,which is a quantum coherent effect when lasersare resonant with atom levels.It can be applied to realize the slow light,photo-quantumstorage,the enhancement of refractive index of medium,microwave detection,and single-photo detection etc.EIT has been observed in different mediums about the dependence oncoherent electromagnetic fields and different system parameters to find the quantumcoherence dynamics.Specially,Rydberg energy levels can be used to form the ladder EIT,which attracts lots of attentions during recent yearsRydberg atom,highly excited atoms with principal quantum number n??1,can beregarded as a Hydrogen-like atom with a single electron around.Rydberg atoms exhibitsome exotic properties,such as large size??n*²?,long lifetimes??n*³?,large polarizability??n*⁷?,narrow energy level gap(?n*^-3).The radio-frequency field can couple the Rydbergenergy level,to control the interaction with Rydberg atoms.This kind of application ofRydberg EIT inaugurate a new way to detection of weak field.In this work,we will investigate the Rydberg EIT quantum coherent effect indifferent frequency of radio-frequency field due to large sensitivity of Rydberg atoms to theexternal field.Two lasers with 852nm and 510nm are counter propagated to each other in the roomtemperature cesium cell.Two-step Rydberg excitation is realized by the process of 6S_1/2 ?6P_3/2 ? nD or nS,which can form the three level ladder system with the ground state,excited state,and the Rydberg state,respectively.EIT signal is detected by the 852nm probelaser.Firstly,the EIT signal is broadened when.the probe laser is modulated by a 1?10 KHzelectric signal.It can be demodulated into two peaks.The distance of the two peaksstrongly depends on the modulation amplitude but not on the modulation frequency.Wedevelop a model to explain the experiment results.This work can be used to the real-time laser-line profiles monitoring.Secondly,we observe the Rydberg EIT spectra with radio-frequency field in the range of 40MHz-80MHz.The sidebands of EIT signal are observed due to the sidebands of Rydberg levels caused by the radio-frequency field.The sidebands of EIT signal are observed in different frequencies,amplitudes,and waveforms of radio-frequency field.The transparency frequency of EIT signal shifts with the radio frequency and additionally the sidebands appear in strong RF field.The sidebands will mix with neighboring manifold states and appear avoided crossings.We use the Floquet method to model the Rydberg EIT spectra,which shows a great agreement with the experiment ones.This could be used to fast read out Rydberg energy level structure and identify the waveforms of the radio-frequency field.Lastly,we use the 16.9GHz radio-frequency field to couple the adjacent Rydberg states and thus observe the effect on Rydberg EIT signal.The two-photon radio-frequency Rydberg spectroscopy and the EIT-AT splitting spectroscopy are obtained.The power of the radio-frequency field and the distance between the RF antenna and the Cs cell are manipulated to observe the change of the EIT-AT splitting.We found that the EIT-AT splitting increasing with the increased power of the radio-frequency field.Rydberg EIT-AT splitting spectra technique can be used to measure radio-frequency field amplitude and polarization precisely.The innovations of this work,1.We create the Rydberg EIT ladder system and investigate the effect of the probe laser modulation amplitude.We find that the EIT width increase with the modulation amplitude with corresponding scale of 2*1.67.It is independent of the modulation frequency.2.We investigate the effect of Rydberg EIT spectra on radio-frequency field with frequency range of 40MHz-80MHz.We find the EIT shift with the even sideband in the sine radio-frequency field,and with the odd sideband in the square radio-frequency field,which has a great agreement with the model we present.3.We study the EIT-AT splitting scales with the radio-frequency field power,which shows the two-photon RF spectroscopy in RF field of 16.9GHz.