Letteratura scientifica selezionata sul tema "Hybrid skin-Topological states"

AbstractRobust boundary states epitomize how deep physics can give rise to concrete experimental signatures with technological promise. Of late, much attention has focused on two distinct mechanisms for boundary robustness—topological protection, as well as the non-Hermitian skin effect. In this work, we report the experimental realizations of hybrid higher-order skin-topological effect, in which the skin effect selectively acts only on the topological boundary modes, not the bulk modes. Our experiments, which are performed on specially designed non-reciprocal 2D and 3D topolectrical circuit lattices, showcases how non-reciprocal pumping and topological localization dynamically interplays to form various states like 2D skin-topological, 3D skin-topological-topological hybrid states, as well as 2D and 3D higher-order non-Hermitian skin states. Realized through our highly versatile and scalable circuit platform, theses states have no Hermitian nor lower-dimensional analog, and pave the way for applications in topological switching and sensing through the simultaneous non-trivial interplay of skin and topological boundary localizations.

Abstract The finding of non-Hermitian skin effect has revolutionized our understanding of non-Hermitian topological phases, where the usual bulk-boundary correspondence is broken and new topological phases specific to non-Hermitian system are uncovered. Hybrid skin-topological effect (HSTE) is a class of newly discovered non-Hermitian topological states that simultaneously supports skin-localized topological edge states and extended bulk states. Here we provide a brief review of HSTE, starting from different mechanics that have been used to realize HSTE, including non-reciprocal couplings, onsite gain/loss, and non-Euclidean lattice geometries. We also review some theoretical developments closely related to the HSTE, including the concept of higher-order non-Hermitian skin effect, parity-time symmetry engineering, and non-Hermitian chiral skin effect. Finally, we summarize recent experimental exploration of HSTE, including its realization in electric circuits systems, non-Hermitian photonic crystals, and active matter systems. We hope this review can make the concept of hybrid-skin effect clearer and inspire new finding of non-Hermitian topological states in higher dimensional systems.

Abstract We investigate the emergence of unconventional corner mode in a two-dimensional topolectrical circuits induced by asymmetric couplings. The non-Hermitian skin effect of two kinked one-dimensional lattices with multiple asymmetric couplings are explored. Then we extend to the two-dimensional model, derive conditions for the non-Hermitian hybrid skin effect and show how the corner states are formed by non-reciprocal pumping based on one-dimensional topological states. We provide explicit electrical circuit setups for realizing our observations via realistic LTspice simulation. Moreover, we show the time varying behaviors of voltage distributions to confirm our results. Our study may help to extend the knowledge on building the topological corner states in the non-Hermitian presence.

AbstractEscalating energy demands of self‐independent on‐skin/wearable electronics impose challenges on corresponding power sources to offer greater power density, permeability, and stretchability. Here, a high‐efficient breathable and stretchable monolithic hybrid triboelectric‐piezoelectric‐electromagnetic nanogenerator‐based electronic skin (TPEG‐skin) is reported via sandwiching a liquid metal mesh with two‐layer topological insulator‐piezoelectric polymer composite nanofibers. TPEG‐skin concurrently extracts biomechanical energy (from body motions) and electromagnetic radiations (from adjacent appliances), operating as epidermal power sources and whole‐body self‐powered sensors. Topological insulators with conductive surface states supply notably enhanced triboelectric and piezoelectric effects, endowing TPEG‐skin with a 288 V output voltage (10 N, 4 Hz), ∼3 times that of state‐of‐the‐art devices. Liquid metal meshes serve as breathable electrodes and extract ambient electromagnetic pollution (±60 V, ±1.6 µA cm−2). TPEG‐skin implements self‐powered physiological and body motion monitoring and system‐level human‐machine interactions. This study provides compatible energy strategies for on‐skin/wearable electronics with high power density, monolithic device integration, and multifunctionality.

Abstract The hybrid skin-topological effect (HSTE) in non-Hermitian systems exhibits both the skin effect and topological protection, offering a novel mechanism for the localization of topological edge states (TESs) in electrons, circuits, and photons. However, it remains unclear whether the HSTE can be realized in quasicrystals, and the unique structure of quasicrystals with multi-site cells may provide novel localization phenomena for TESs induced by the HSTE. In this Letter, we propose an eight-site cell in two-dimensional quasicrystals for the first time and realize the HSTE with eight-site nonreciprocal intracell hoppings. Furthermore, we can arbitrarily adjust the eigenfield distributions of the TESs and discover domain walls associated with effective dissipation and their correlation with localization. We present a new scheme to precisely adjust the energy distribution in non-Hermitian quasicrystals with arbitrary polygonal outer boundaries.

AbstractDespite the considerable effort, fast and highly sensitive photodetection is not widely available at the low-photon-energy range (~meV) of the electromagnetic spectrum, owing to the challenging light funneling into small active areas with efficient conversion into an electrical signal. Here, we provide an alternative strategy by efficiently integrating and manipulating at the nanoscale the optoelectronic properties of topological Dirac semimetal PtSe2 and its van der Waals heterostructures. Explicitly, we realize strong plasmonic antenna coupling to semimetal states near the skin-depth regime (λ/104), featuring colossal photoresponse by in-plane symmetry breaking. The observed spontaneous and polarization-sensitive photocurrent are correlated to strong coupling with the nonequilibrium states in PtSe2 Dirac semimetal, yielding efficient light absorption in the photon range below 1.24 meV with responsivity exceeding ∼0.2 A/W and noise-equivalent power (NEP) less than ~38 pW/Hz0.5, as well as superb ambient stability. Present results pave the way to efficient engineering of a topological semimetal for high-speed and low-energy photon harvesting in areas such as biomedical imaging, remote sensing or security applications.

Cette thèse explore l'intersection entre la physique non-hermitienne et les métamatériaux acoustiques topologiques, en se concentrant sur la manipulation de la propagation des ondes acoustiques dans des systèmes tels que les chaînes de Su-Schrieffer-Heeger et les isolants de Chern. À travers une combinaison de modélisation théorique et de simulations numériques, ce travail démontre comment la perte sur site et les interactions non réciproques peuvent être utilisées pour contrôler la topologie et induire la non-Hermiticité. La thèse explore également une méthode potentielle pour concevoir des isolants de Chern non-Hermitiens et obtenir des états acoustiques hybrides de type skin-topologique. En comblant l'écart entre les concepts théoriques et les applications potentielles, ce travail fait progresser la compréhension des métamatériaux topologiques non-Hermitiens et ouvre de nouvelles perspectives pour de futures recherches tant en physique fondamentale qu'en acoustique appliquée
This thesis explores the intersection of non-Hermitian physics and topological acoustic metamaterials, focusing on the manipulation of acoustic wave propagation in systems such as the Su-Schrieffer-Heeger chains and Chern insulators. Through a combination of theoretical modeling and numerical simulations, the work demonstrates how onsite loss and non-reciprocal interactions can be used to control topology and induce non-Hermiticity. The thesis also explore the potential method to design non-Hermitian Chern insulator and obtain the acoustic hybrid skin-topological states. By bridging the gap between theoretical concepts and potential applications, this work advances the understanding of non-Hermitian topological metamaterials and opens new avenues for future research in both fundamental physics and applied acoustics