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

We propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Λ&l...

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Main Authors: Xiao Liu, Maurizio Artoni, Giuseppe La Rocca, Jinhui Wu
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Photonics
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Online Access:https://www.mdpi.com/2304-6732/12/5/521
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author Xiao Liu
Maurizio Artoni
Giuseppe La Rocca
Jinhui Wu
author_facet Xiao Liu
Maurizio Artoni
Giuseppe La Rocca
Jinhui Wu
author_sort Xiao Liu
collection DOAJ
description We propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Λ</mi></semantics></math></inline-formula> 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 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>π</mi><mo>/</mo><mn>4</mn></mrow></semantics></math></inline-formula> 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.
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spelling doaj-art-4d30f243763c4fe29884625e3bd2864d2025-08-20T01:56:39ZengMDPI AGPhotonics2304-67322025-05-0112552110.3390/photonics12050521Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave MixingXiao Liu0Maurizio Artoni1Giuseppe La Rocca2Jinhui Wu3Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, ChinaDepartment of Engineering and Information Technology, Brescia University, 25133 Brescia, ItalyNational Enterprise for Nanoscience and Nanotechnology, Scuola Normale Superiore, 56126 Pisa, ItalyCenter for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, ChinaWe propose a scheme for realizing nonreciprocal optical scattering with non-Hermitian four-wave mixing (FWM) in a double-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Λ</mi></semantics></math></inline-formula> 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 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>π</mi><mo>/</mo><mn>4</mn></mrow></semantics></math></inline-formula> 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.https://www.mdpi.com/2304-6732/12/5/521non-Hermitian four-wave mixingmulti-channel nonreciprocal scatteringunidirectional transport and directional blockade
spellingShingle Xiao Liu
Maurizio Artoni
Giuseppe La Rocca
Jinhui Wu
Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
Photonics
non-Hermitian four-wave mixing
multi-channel nonreciprocal scattering
unidirectional transport and directional blockade
title Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
title_full Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
title_fullStr Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
title_full_unstemmed Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
title_short Optical Unidirectional Transport and Directional Blockade in Cold Atoms via Non-Hermitian Four-Wave Mixing
title_sort optical unidirectional transport and directional blockade in cold atoms via non hermitian four wave mixing
topic non-Hermitian four-wave mixing
multi-channel nonreciprocal scattering
unidirectional transport and directional blockade
url https://www.mdpi.com/2304-6732/12/5/521
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AT giuseppelarocca opticalunidirectionaltransportanddirectionalblockadeincoldatomsvianonhermitianfourwavemixing
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