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Related papers: Non-Reciprocal Willis Coupling in Zero-Index Movin…

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Light is generally expected to travel through isotropic media independent of its direction. This makes it challenging to develop non-reciprocal optical elements like optical diodes or circulators, which currently rely on magneto-optical…

Acoustic meta-atoms serve as the building blocks of metamaterials, with linear properties designed to achieve functions such as beam steering, cloaking and focusing. They have also been used to shape the characteristics of incident acoustic…

Applied Physics · Physics 2022-02-15 Shahrokh Sepehrirahnama , Sebastian Oberst , Yan Kei Chiang , David A. Powell

Funneling acoustic waves through largely mismatched channels is of fundamental importance to tailor and transmit sound for a variety of applications. In electromagnetics, zero-permittivity metamaterials have been used to enhance the…

Classical Physics · Physics 2018-12-21 H. Esfahlani , M. S. Byrne , M. McDermott , A. Alù

The recent surge of interest in temporal modulation schemes to induce magnet-free non-reciprocity has inspired several exciting opportunities for photonic technology. Here, we investigate a scheme to realize free-space isolators and highly…

Optics · Physics 2018-03-14 Romain Fleury , Dimitrios L. Sounas , Andrea Alu

Nonlinear mechanical metamaterials can exhibit emergent transport phenomena that mimic topological protection without relying on linear band topology. Here, we realize a bifurcation-induced nonreciprocal lattice that supports robust…

Materials Science · Physics 2026-02-05 Brahim Lemkalli , Qingxiang Ji , Jingyi Zhang , Richard Craster , Johan Christensen , Muamer Kadic

The extent to which non-reciprocal waves can be guided in arbitrary directions is an interesting question. We address one aspect of this problem by studying the propagation of acoustic spin waves in a narrow physical conduit made of a…

Materials Science · Physics 2025-05-13 Jean-Paul Adam , Nathalie Bardou , Aurélie Solignac , Joo-Von Kim , Thibaut Devolder

Nonreciprocal optics enables asymmetric transmission of light when its sources and detectors are exchanged. A canonical example -- optical isolator -- enables light propagation in only one direction, similar to how electrical diodes enable…

Acoustic metamaterials are structures with exotic acoustic properties, having promising applications in acoustic beam steering, focusing, impedance matching, absorption and isolation. Recent work has shown that the efficiency of many…

Classical Physics · Physics 2019-08-29 Anton Melnikov , Li Quan , Sebastian Oberst , Andrea Alù , Steffen Marburg , David Powell

Reciprocity, the principle that a system response is identical in the forward path compared to the backward path, is a fundamental concept across physics, from electrical circuits and optics to acoustics and heat conduction. Nonreciprocity…

Materials Science · Physics 2025-08-01 Thomas J. Ugras , Daniel J. Gracias , Oriol Arteaga , Richard D. Robinson

Nonreciprocity, the defining characteristic of isolators, circulators and a wealth of other applications in radio/microwave communications technologies, is in general difficult to achieve as most physical systems incorporate symmetries that…

Optical nonreciprocity is the phenomenon where light behaves differently when traveling in the forward direction compared to the backward direction. This nonreciprocal behavior is typically achieved in systems that exhibit electromagnetic…

Optics · Physics 2025-08-19 Dheeraj Pratap

Physical systems with material properties modulated in time provide versatile routes for designing magnetless nonreciprocal devices. Traditionally, nonreciprocity in such systems is achieved exploiting both temporal and spatial modulations,…

We prove the possibility of achieving non-reciprocal wave propagation in space-time modulated media and give an asymptotic analysis of the non-reciprocity property in terms of the amplitude of the time-modulation. Such modulation causes a…

Analysis of PDEs · Mathematics 2021-09-16 Habib Ammari , Jinghao Cao , Erik Orvehed Hiltunen

Synthetic magnetism has been recently realized using spatiotemporal modulation patterns, producing non-reciprocal steering of charge-neutral particles such as photons and phonons. Here, we design and experimentally demonstrate a…

Applied Physics · Physics 2022-10-03 Zhaoxian Chen , Zhengwei Li , Jingkai Weng , Bin Liang , Yanqing Lu , Jianchun Cheng , Andrea Alu

Electromagnetic bi-anisotropy finds an analogy in acoustic metamaterial science as Willis coupling. Its impact and emergence in the field of elastodynamic metamaterials is not as well understood however, given the coupling between…

Applied Physics · Physics 2025-05-09 Philip A Cotterill , David Nigro , William J. Parnell

In a moving acoustic medium, sound waves travel differently with and against the fluid flow. This well-established acoustic effect is backed by the intuition that the fluid velocity bias imparts momentum on the propagating acoustic waves,…

Fluid Dynamics · Physics 2022-01-03 Ohad Silbiger , Yakir Hadad

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations to wave propagation. However, it is challenging to realize efficient and ultrafast temporal modulation in a photonic…

Optics · Physics 2022-11-11 Xuexue Guo , Yimin Ding , Yao Duan , Xingjie Ni

Time has emerged as a new degree of freedom for metamaterials, promising new pathways in wave control. However, electromagnetism suffers from limitations in the modulation speed of material parameters. Here we argue that these limitations…

Mesoscale and Nanoscale Physics · Physics 2019-11-20 E. Galiffi , P. A. Huidobro , J. B. Pendry

Non-reciprocal devices, which allow the non-reciprocal signal routing, serve as the fundamental elements in photonic and microwave circuits and are crucial in both classical and quantum information processing. The radiation-pressure-induced…

Reciprocity is one of the fundamental characteristics of wave propagation in linear time-invariant media with preserved time-reversal symmetry. Breaking reciprocity opens the way to numerous applications in the fields of phononics and…

Applied Physics · Physics 2024-09-09 Matthieu Malléjac , Romain Fleury