Manipulations Of Light Propagation Based On Dipole-Dipole Interactions Between Rydberg Atoms

Rydberg atoms are atoms in which the outermost valence electrons are excited to orbitals with high principal quantum numbers,exhibiting characteristics such as large orbital radius,long radiative lifetimes,and naturally occurring non-local strong dipoledipole interactions between atoms.The strong interactions between Rydberg atoms give rise to classical blockade and anti-blockade effects in Rydberg atomic gases,which have found significant applications in fields such as quantum optics,quantum communications,quantum many-body simulations,and quantum precision measurements.Considering the limitations of optical phenomena in natural linear materials,this dissertation aims to investigate the impact of interactions between Rydberg atoms and the two classical effects of blockade and anti-blockade on the propagation of light fields on either side of a Rydberg atomic gas medium,providing theoretical techniques for the development of Rydberg atoms in new optical devices.Electromagnetically induced transparency(EIT)is a commonly used technique to manipulate the optical effects of the medium.By applying this technique to Rydberg atomic gas and combining the quantum interference effect of EIT with the Rydberg blockade and anti-blockade effects,the strong dipole-dipole interactions between Rydberg atoms can be mapped to strong photon-photon interactions,generating strong cooperative optical nonlinear effects.This Rydberg EIT technique expands the research in the field of nonlinear optics,providing significant technical support for optical communication,spectroscopy,and the development of the novel optical device.In this dissertation,the Rydberg atom system is used as a feasible physical platform,combining the non-local dipole-dipole interactions between Rydberg atoms,the Rydberg blockade and anti-blockade effects,and the Rydberg EIT technique to modulate the optical responses of the medium and then alter its optical susceptibility.Specifically,we design the spatial Kramers-Kronig(KK)medium to investigate the reflection phenomena on both sides of the medium,and we manipulate the refractive index of the medium to investigate the Goos-H(?)nchen(GH)lateral shift of reflection and transmission on the surface of the medium.First,we take advantage of the non-local long-range van de Waals interactions between Rydberg atoms to place an equidistant control atomic ring outside a uniform target atomic sample,mapping the Kramers-Kronig(KK)relation between the dispersion and absorption responses of the medium to the signal field from the frequency domain to the spatial domain.Among them,the three-level configuration of the target atoms is adiabatically eliminated into a two-level configuration under the condition of single-photon large detuning and two-photon resonance,while the control atoms are in the maximum Rydberg excitations due to the Rydberg anti-blockade driving scheme.We find,in particular,it is viable to realize a tunable spatial KK relation supporting asymmetric and even unidirectional reflection for appropriate pumping frequencies or signal frequencies in a desired range depending on the frequency of the coupling field.Taking a periodic lattice of target atoms instead,the multiple Bragg scattering can be incorporated into the spatial KK relation in order to enhance the nonzero reflectivity yet without breaking the asymmetric or unidirectional reflection.In this work,a tunable spatial KK relation and a unidirectional reflection are achieved with Rydberg interactions and light field modulation in a fixed atomic medium,which is instructive for developing unidirectional optical devices and exploring new applications with long-range van der Waals interactions.Furthermore,we utilize the strong Kerr nonlinear optical effect induced by the strong long-range dipole-dipole interactions between Rydberg atoms and present a theoretical investigation on the Goos-H(?)nchen(GH)lateral shift of a probe field as it is reflected or transmitted from a three-layer system with a Rydberg atomic gas sandwiched between two dielectric slabs.Among them,each Rydberg atom in the system is driven by a weak probe field and a strong coupling field,and there exist correlations between atoms due to the interactions.Non-local and nonlinear Kerr effects can occur in such atomic gases,and their strengths are obviously dependent on the atomic density.The research shows that the resultant GH shift is distinct from that observed in an extremely diluted atomic gas with negligible Rydberg dipole-dipole interactions and has been examined in two particular cases specified by different coupling frequencies for a fixed probe frequency.In both cases,the non-local Kerr effect is found to result in an obvious enhancement of the GH shift and more importantly provide an alternative way for controlling the GH shift by varying the atomic density in an appropriate range.Finally,we present a possible realization of a highly sensitive displacement sensor by exploiting an approximately linear relation between the displacement of one dielectric slab and the GH shift of the probe field.