Anomalous Properties Of Electromagnetically Induced Grating With Rydberg Atoms

Rydberg atom typically played by alkali-metal atom,is a highly excited atom in which the outermost one electron is excited to an energy level with large principal quantum numbers.Compared with neutral ground atoms,Rydberg atoms have some unique intrinsic properties,such as long lifetime,strong long-range interaction,and huge electric dipole moment.In recent years,Rydberg atoms have been widely applied in the frontiers of quantum information technology,quantum devices,atomic entanglement,quantum logic gates and so on.In particular,Rydberg atom can be used to induce strong interactions between optical field and atoms,promising potential applications in the area of atomic optics.In the present paper,a novel method for diffracting the weak probe beam into unidirectional and higher-order directions is proposed via Rydberg electromagnetically induced grating(Rydberg-EIT)mechanism.The basic idea lies in a proper spatial modulation for the parity of the probe dispersion implemented by a space-dependent two-photon detuning,besides of the existing standing-wave coupling field in the EIT scenario.It is observed that by using an appropriate two-photon modulation amplitude,a perfect unidirectional diffraction grating can be realized.In addition,due to the mutual effect between the van der Waals interaction and the atom-field interaction length that deeply improves the dispersion of the medium,the probe field energy can be counterintuitively transferred into higher-order diffractions as increasing the vdWs interaction,leading to the realization of a controllable higher-order diffraction grating via a strong blockade.Our results provide new prospective for the realization of unidirectional and high-order diffraction grating in experiment,offering fundamental basis for the creation of new quantum optical devices with Rydberg atoms.