Nonlocal Optical Solitons And Their Manipulation In Ultracold Rydberg Atomic Gases

Rydberg atom has attracted great attention due to its wide application and rapid progress in related experiments.Rydberg atom refers to the atom in which the outer electrons are excited to the highly-excited electronic state with high principal quantum number.Because the highly-excited electronic states where an electron is far from the nucleus,Rydberg atom has some unique properties that other low excited atoms do not have.Rydberg atoms have large atomic scales,long lifetime,large electric dipole moment,large electric polarizability,and strong dipole-dipole interaction.Furthermore,the dipole-dipole interaction between Rydberg atoms can be controlled in a range of about 12 orders of magnitude.These unique properties make Rydberg atoms have many potential applications,including optical sensing,quantum information and computation,quantum simulation,quantum nonlinear optics and so on.The conventional nonlinear optics mainly studies the strong optical nonlinear ef-fect induced by the interaction between strong laser field and optical medium.Under the condition of weak laser field,the nonlinear effect of medium can be ignored.The discovery of electromagnetically induced transparency(EIT)has realized the lossless propagation of probe field in the optical medium under resonance condition,which can produce significant optical nonlinear effect under weak probe field intensity,greatly promoting the development of weak light nonlinear optics and its application in all-optical switching and optical information processing.Ultracold Rydberg EIT can en-hance the optical Kerr nonlinearity.The giant Kerr nonlinearity in Rydberg-EIT systems comes from the strong Rydberg-Rydberg interaction between atoms,which can be five orders of magnitude larger than the traditional EIT systems.In the dissertation,we shall investigate nonlocal optical soliton and their active manipulation the in ultracold Rydberg atomic gases,which include:(i)Study the for-mation and cloning of nonlocal solitons in the ultracold Rydberg atomic system based on the giant Kerr nonlocal nonlinear effect;(ii)Study the formation and propagation of nonlocal spatial-temporal soliton molecule and vortex molecule in the ultracold Ryd-berg atomic system,and their storage and retrieval;(iii)Study controllable PT phase transition and asymmetric soliton scattering in atomic gases with linear and nonlinear potentials.The main work contains the following aspects:1.Study high-fidelity and controllable cloning of high-dimensional optical beams with a Rydberg atomic gas.We start with considering a cold gas of Rydberg atoms with an inverted Y -type four-level configuration.We propose a scheme to realize the cloning of high-dimensional(high-D)optical beams with a Rydberg atomic gas via electromagnetically induced transparency.We show that strong atom-atom interaction can map to two probe laser fields,which may acquire giant nonlocal Kerr nonlinearities supporting the formation of stable high-D optical solitons and vortices at very low light power.We also show that such optical solitons and vortices prepared in one probe field can be cloned onto another one with high fidelity,and the cloning may be actively manipulated through the tuning of the nonlocality degree of the Kerr nonlinearities.Moreover,we demon-strate that based on such a cloning scheme multitimes and multicomponents cloning of high-D optical beams are also possible,which allows us to acquire multiple copies of high-D optical beams.The results on the optical cloning are not only of fundamental interest for nonlocal nonlinear optics but also promising for practical applications in optical information processing and transmission.2.Study large-size nonlocal high-dimensional optical soliton molecules and their storage and retrieval.We start with considering a cold gas of Rydberg atoms with an Ladder-type three level configuration.We propose a scheme to acquire nonlocal optical soliton molecules with a system of cold Rydberg atomic gas working under the condition of electromagnetically induced transparency.We show that,due to the EIT and the strong long range Rydberg-Rydberg interaction between Rydberg atoms,the system supports giant nonlocal optical Kerr nonlinearity and hence the formation of nonlocal(2+1)-dimensional spatial soli-ton(vortex)molecules,having large sizes,low generation powers,and can be active controlled by the nonlocality degree of nonlocal Kerr nonlinearity.We also show that the system allows the formation of nonlocal(3+1)-dimensional spatial-temporal soliton(vortex)molecules with ultraslow velocities and very low generation powers,which can further be stored and retrieved through switching off and on a control laser field.The findings bring insights to the long-range atom-atom interaction for realizing novel soli-ton molecules and achieving their active control,promising for applications in optical information processing and transmission.3.Study controllable PT phase transition and asymmetric soliton scattering in atomic gases with linear and nonlinear potentials.The atomic excitation scheme given by a N type four level model can be taken as a sys-tem of optically pumped electromagnetically induced transparency(EIT),consisting of a standard three-level ?-type EIT plus an optical pumping used to provide an active Raman gain to the signal field.We show that the combined linear and nonlinear PT -symmetric potentials can be created through the spatial modulation of the control laser field and the inclusion of the Kerr nonlinearity of the signal laser field.We demonstrate that the imaginary part of the nonlinear PT potential plays a crucial role for the occur-rence of the PT phase transition and the change of the PT phase diagram,which can be actively manipulated in our system.Furthermore,by taking the combined linear and nonlinear PT potentials as a defect,the scattering of the optical solitons by the defect displays evident asymmetric behavior,controlled by the imaginary parts of the com-bined linear and nonlinear PT potentials.The results may have potential applications in optical information processing and transmission.