Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing

Year: 2025

Authors: Liu X., Artoni M., La Rocca G., Wu JH.

Autors Affiliation: Northeast Normal Univ, Ctr Quantum Sci, Changchun 130024, Peoples R China; Northeast Normal Univ, Sch Phys, Changchun 130024, Peoples R China; Brescia Univ, Dept Engn & Informat Technol, I-25133 Brescia, Italy; Ist Nazl Ott CNR CNR INO, European Lab Nonlinear Spect, I-50019 Sesto Fiorentino, Italy; Scuola Normale Super Pisa, Natl Enterprise Nanosci & Nanotechnol, I-56126 Pisa, Italy.

Abstract: We propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-Lambda system of cold atoms driven by coupling and dressing phase-mismatched standing-wave (SW) fields. Four scattering channels-direct transmission, cross transmission, direct reflection, and cross reflection-can be established for a probe and a signal field, some of which are nonreciprocal due to non-Hermitian spatial modulations when the two SW driving fields exhibit a pi/4 phase shift. We find in particular that it is viable to attain single-color unidirectional transport, dual-color unidirectional transport, and single-color directional blockade with respect to a probe and a signal field incident upon this atomic sample from the same side, due to perfect destructive interference between direct and cross scattering channels. This work provides a new paradigm for studying non-Hermitian nonlinear optics and offers a theoretical foundation for designing all-optical atomic devices based on multi-channel nonreciprocal scattering.

Journal/Review: PHOTONICS

Volume: 12 (5)      Pages from: 521-1  to: 521-11

More Information: This work is supported by the National Natural Science Foundation of China (No. 62375047), the Italian PNRR MUR (No. PE0000023-NQSTI), I-PHOQS (Photonics and Quantum Sciences, PdGP/GePro 2024-2026), and the Fund for International Activities of the University of Brescia.
KeyWords: non-Hermitian four-wave mixing; multi-channel nonreciprocal scattering; unidirectional transport and directional blockade
DOI: 10.3390/photonics12050521