Disorder and Electric Fields Enable Arbitrary Control of Non-Hermitian Skin Modes in Two-Dimensional Systems

The unusual behaviour known as the non-Hermitian skin effect, where quantum states concentrate at the edges of a material, presents both fundamental challenges and exciting possibilities for new technologies. Zhao-Fan Cai, Yang Li, and Yu-Ran Zhang, alongside colleagues at the South China University of Technology, now demonstrate a method for precisely controlling this effect in two-dimensional materials. The team achieves this control by carefully combining the introduction of disorder, deliberate imperfections within the material, with the application of an electric field, allowing them to steer the accumulation of these edge states. This breakthrough offers a robust and tunable mechanism for engineering how energy and information accumulate and travel along material boundaries, potentially opening doors to innovative designs for classical devices and beyond.

This work demonstrates the ability to manipulate these boundary states using a combination of disorder and an applied electric field. By carefully tuning both the disorder strength and the electric field, the team shows that skin modes can be arbitrarily localized at any desired boundary, or even delocalized across the entire system. This control arises from a complex interplay between disorder-induced scattering and electric-field-driven redistribution of wave functions, establishing a novel pathway for manipulating non-Hermitian boundary states and potentially enabling advanced functionalities in topological photonics and metamaterials.

Directed Energy Localization in Non-Hermitian Systems

Scientists demonstrate precise control over the localization of energy within two-dimensional non-Hermitian systems, achieving a breakthrough in manipulating how energy propagates in these unique materials. The research focuses on the non-Hermitian skin effect, where energy concentrates at the edges of a material, and reveals a method to direct this concentration to arbitrary locations along the boundary. The team employed a two-dimensional model subject to an external electric field and random disorder, allowing them to finely tune the localization of energy. Experiments show that the electric field alone suppresses the natural tendency of the skin effect to concentrate energy at the boundary in a clean system.

However, the introduction of disorder creates a remarkable effect: it induces energy transport perpendicular to the electric field, effectively guiding the energy. By carefully aligning the electric field and the direction of this induced transport, scientists can precisely control where energy accumulates along the boundary. Results demonstrate that the center-of-mass of an initial wave packet can be steered to any desired location, showcasing complete control over boundary localization. This functionality, unattainable in previously studied non-Hermitian systems, opens new avenues for designing materials with tailored energy flow characteristics, with potential applications in both classical and quantum materials.

Electric Fields Control Boundary State Accumulation

Scientists have demonstrated precise control over the behaviour of waves in non-Hermitian systems, achieving a significant advance in manipulating how energy and information propagate. Their research focuses on the non-Hermitian skin effect, where states accumulate at the boundaries of a material, and reveals a method to manipulate this effect using a combination of disorder and an applied electric field. By carefully aligning the electric field with the direction of non-reciprocal movement within the system, researchers can direct the localization of these boundary states to specific locations. This work establishes a unified framework for understanding and controlling wave behaviour in these complex systems, offering a versatile mechanism for engineering tunable boundary accumulation.

The team showed that an electric field alone suppresses the skin effect, but when combined with disorder, it enables control over the direction of wave packet propagation, allowing for arbitrary positioning of boundary localization. This synergistic interplay between the skin effect, disorder, and the electric field represents a key breakthrough. This research opens new avenues for wave control and transport phenomena, with potential applications spanning classical and quantum technologies.