Studies On Three-dimensional Atomic Localization Based On Spontaneously Generated Coherence

In recent years,the precision measurement of moving atoms' position is an important frontier in the field of laser physics,which has aroused people's wide attention and research.There are many potential applications of three-dimensional atomic localization in the optical control of atomic freedom,such as laser cooling,neutral atom trapping,Bose-Einstein Condensation,atom lithograghy as well as measurement of center-of-mass wave function.Using optical means and technology to measure the position of atoms can provide high precision and spatial resolution,so a lot of researches on theory and experiment have access to atom localization project.There are many ways to get atomic localization.According to the interaction between the standing wave field and the atom,some people measure the position of atom via detecting the phase shift of the standing wave field or atomic dipole in the early time.Then people began to use the entanglement between the position of atoms and their internal state or the method of resonance projection.The researchers found that the measurement accuracy could reach 10 nanometers based on the scheme of light absorption mask later.According to the atomic coherence and the quantum interference effect,some researchers put forward a series of atom localization plans recently,realizing the localization of the atom in range of subwavelength and subsemi-wavelength.In this paper,we mainly studied the three-dimensional localization of moving atoms via the spontaneously generated coherence.By adjusting the parameters of the system,the probability of finding atoms in three-dimensional space can reach 100%.First of all,using the coherence of the spontaneous radiation to obtain the three dimensional atom localization in the space,we studied the four-level Y type atomic system driven by the microwave field.In this scheme,the microwave field and the standing wave field operated on the four-level Y-type atomic system,forming a closed structure.Microwave field and three standing wave fields can greatly enhance the detection probability and local precision.While the atom somehow passes through the orthogonal standing wave fields,the interaction of light and atoms depends on the position of the three dimensional space.Adjusting parameters of the system,such as phase,amplitude and initial distribution,can significantly change the 3D position detection accuracy and resolution of the atoms.The probability of an atom being detected in the cubic volume of wavelength can reach to 100%.Next,we analyzed the three-dimensional atomic localization of Tripod atomic system based on spontaneous radiation.The atomic coherence and quantum interference effects produced by the interaction of multi-level atom,coherent optical field,microwave field or static electric field can regulate spontaneous emission.We used the weak detection field and the orthogonal standing wave field combination with the tripod atomic system transition.And the interaction between the atom and the light field was modulated in the three-dimensional space of the standing wave field.So the spontaneous emission spectra could provide the location information of the atom,and we could certainly realize the high precision three-dimensional atomic localization as well.Finally,we investigated the inverted Y type atomic system interacting with three perpendicular standing wave fields.Three orthogonal standing wave fields were coupled to the three transitions of the inverted Y type atomic system,while the highest excited state and the intermediate excited state were coupled to the vacuum field respectively.When the moving atom entered the standing wave field,the interaction between light and matter was spatially dependent.The spontaneous emission spectrum of two different spontaneous radiation channels could also carry the position information of the atom.While the spontaneous emission of photons was detected at a particular frequency,the maximum probability is 100%to measure an atom at a particular localization just through adjusting the parameters of the system.Furthermore,it could realize high precision and high resolution three-dimensional atomic localization.