The Study On Pair Production In Asymmetric Potential Well

With the development of laser technology,the topic of a direct conversion of energy to matter,such as electron-positron pair production,has become a very interesting research project.Vacuum pair production is a novel prediction of quantum electrodynamics,which yet to be tested.Theoretical study of vacuum pair production can extract more the true pictures of this process and can be the direction for experiment.In this thesis,by using numerical simulation,we study the mechanism of ‘the electron-positron pair production in vacuum' in asymmetric Sauter potential well.We provide momentum spectrum,location distribution and total yields of the electron-positron pair in the asymmetric potential well,and compare them with the symmetric case.Via electron momentum spectrum we obtained free electron energy in asymmetric potential well.The relationship between created electron energy,bound state energy and photon energy in the symmetric potential well is used to the study problem for the created electrons in the asymmetric potential well and its validity is confirmed by this approximation.By the location distribution of the electron we have also shown the reason why the momentum spectrum has an optimization in the asymmetric well compared with the symmetric one.This thesis contains the following three parts.The first part: in Chapter 1,first,we briefly review the current status of this research topic,including the Schwinger effects,multi-photon process and laser technology.And then,we give motivation,contents,and innovation of this work.In Chapter 2,we present theoretical methods,namely,the advantages and disadvantages of the computational quantum field theory(CQFT),further more we discuss the splitting operator and the fast Fourier transform(FFT).The second part: in Chapter 3,we discuss the electron-positron pair production under the Sauter field in one-dimension.The asymmetric potential well is established when the width of one side of the potential well is fixed and the other side takes different values.By numerical simulation,the momentum spectrum,spatial distribution and yields of electrons under this asymmetric potential well are well studied.Finally,we compare this data with the symmetric potential well and the results are optimized,and the reasons and factors for the optimization are given with evidence.The third part: in Chapter 4,we study the influence of the distance and the direction of the electric field on the pair production and the quantum interference effect produced by changing the distance and direction between the two electric fields.We found that the yields of electron-positron pair changes in vibratility as the width of the potential well becomes wider within a certain distance.Beyond a certain range,to be more precise,there is no significant change after reaching the extreme value.