Explore the groundbreaking research on the non-Hermitian skin effect and its intricate connection to point-gap topology, which could revolutionize our understanding of wave phenomena and open new frontiers in various scientific fields.
The Non-Hermitian lizard and its landscape
The ground in the non-Hermitian world of physics has begun to move fast — there is a buzz around it with new opportunities and possibilities of wave manipulation. Central to this investigation is the so-called non-Hermitian skin effect (NHSE), an intriguing signature of the non-equilibrium topology which fundamentally contradicts with our classical perception based on Bloch bad theory.
While Hermitian energy spectra can be smooth functions with predictable properties, exceptional points in non-Hermitian systems are extraordinarily sensitive to the behavior of the system at its edges. At the boundaries of the system, these lead to a proliferation in much larger number of spacetime eigenstates, which is the signature feature of NHSE. This fundamental finding establishes a novel direction in wave control and device design with currently envisioned applications across scientific disciplines, from optics/photonics to acoustics/metamaterials.
Deconstructing the NHSE from a Topological Perspective
A study headed by Dr. Haiping Hu at the Institute of Physics, Chinese Academy of Sciences (IOP
The NHSE of one-dimensional (1D) systems are well studied and can be modeled by the non-Bloch band theory. This complication only increases when considering higher dimensions for which there exist a wide variety of lattice structures, which complicates the effects of open boundary conditions (OBC) on the NHSE.
The remarkable connection between the NHSE and system’s point-gap topology was discovered by the pioneering work of Dr. Hu To eliminate these point gaps that cause the spectral windings, the researchers were allowed to have a non-Bloch spectra of the system by introducing virtual gauge transformations in a higher dimensions. This is a novel strategy that not only ensures the generality and versatility of the identified spectral signatures, but also illustrates a unified picture for describing NHSE in diverse dimensional systems in-person, encompassing spectral structures themselves rather than any crystal lattice-geometry specifics.
Conclusion
Dr. Haiping Hu revealed that the skin effect in non-Hermitian systems is topologically linked and published this crucial work online which marks an important milestone for our understanding of wave transport in non-conservative systems. This work uncovers the correlation between NHSE and point-gap topology, thereby providing a platform for further investigations targeting the control of skin modes and development of new functional devices across diverse fields of scientific research. These new results bode well for the field of non-Hermitian physics and what might soon be possible in wave control and our understanding of the world.
