Quantum optics using Rydberg atoms and atomic lattices

In this talk, I introduce our recent theoretical advances in quantum optics using Rydberg atoms and atomic lattices by exploring novel phenomena and potential applications. First, I show that it is viable to attain the exact parity-time (PT) anti-symmetry in terms of probe susceptibility when the cold atoms trapped in a 1D optical lattice are driven into the N-type EIT configuration under suitable situations. Atomic media with such unusual PT anti-symmetry are found to exhibit fascinating scattering properties like unidirectional light reflection and coherent perfect absorption, which may be used to realize typically impossible photonic devices in quantum network. These phenomena are closely related with non-Hermitian degeneracy and can be well understood with topological analysis of scattering matrix eigenvalues and unbalanced reflection amplitudes. Second, I present some numerical results on nonlinear EIT when a high Rydberg state of long radiative lifetime and strong dipole interaction is involved in the coherent light-matter interaction. It is found that such EIT media usually exhibit a cooperative susceptibility as a superposition of individual susceptibilities of two different level configurations depending on the Rydberg excitation suffering a blockade effect. Such results are then extended from a simple three-level system to a complicated five-level system so that efficient cross-phase modulation may be attained with low absorptive loss and high state fidelity, which is desired to develop a deterministic photon-photon gate. Special properties of light storage in cold Rydberg atoms are also briefly envisioned with an incomplete numerical technique.
[1] Jin-Hui Wu, M. Artoni, and G. C. La Rocca, Phys. Rev. Lett. 113, 123004 (2014).
[2] Jin-Hui Wu, M. Artoni, and G. C. La Rocca, Phys. Rev. A 91, 0338111 (2015).
[3] Jin-Hui Wu, M. Artoni, and G. C. La Rocca, Sci. Rep. 6, 35356 (2016).
[4] Yi-Mou Liu, Dong Yan, Xue-Dong Tian, Cui-Li Cui, and Jin-Hui Wu, Phys. Rev. A 89, 033839 (2014).
[5] Jin-Hui Wu, M. Artoni, and G. C. La Rocca, Phys. Rev. A 92, 063805 (2015).
[6] Jin-Hui Wu, F. Cataliotti, M. Artoni, and G. C. La Rocca, in submission.