Researchers at the Indian Institute of Science Education and Research Berhampur have achieved strong chiral transfer, directional movement, of topological edge states within a Su-Schrieffer-Heeger chain using precisely tuned gain and loss parameters at its boundaries. This method reliably moves quantum information carried by these states without disrupting core properties; this “switching” relies on carefully controlling gain and loss at the system’s boundaries.

By tuning these boundary conditions, they achieved directional movement, or chiral transfer, of these strong states without disrupting their fundamental properties or affecting overall energy levels within the material itself. Researchers devised a method for moving quantum information carried within topological edge states, pathways existing on materials’ boundaries, without disruption to core characteristics. Their approach centres around manipulating gain and loss parameters at the edges of a Su-Schrieffer-Heeger chain, a simplified model representing a line of atoms where electrons behave unusually due to varying bond strengths between them.

Key to success is using Exceptional Points (EPs), understood like mixing red and blue paint until you get only purple: singular conditions allowing unique control over system behaviour. This allows for chiral transfer, directional movement akin to a one-way street for these quantum signals ensuring reliable transmission from start to finish without scattering or loss.

Analytical Exceptional Point Coordinates Enable Scalable High Fidelity Transfer

Perfect fidelity (100%) was achieved when transferring topological edge states, significantly improving upon previous methods limited to two-level or small systems. Large scale transfers were previously impossible due to disruption of core energy characteristics. This breakthrough resulted from analytically deriving precise coordinates for exceptional points, singular conditions enabling unique control within a Su-Schrieffer-Heeger chain.

Tuning gain and loss parameters at material boundaries and dynamically encircling these boundary EPs enabled strong chiral transfer of quantum information without affecting bulk energy bands; this establishes a scalable framework for controllable switches in future technologies. The particular analytical solution holds true regardless of whether system size exceeds N=1, challenging prior methods. Precisely tuning gain and loss to dynamically control edge state flow while encircling those boundary exceptional points allowed perfect transmission across the lattice without disturbing core energy bands.

Analytical precision must yield to inevitable material disorder

Although this research provides an analytical method for controlling edge states, avoiding approximations needed in larger systems, it doesn’t address sensitivity to real-world imperfections. Strict confinement of gain and loss solely at material edges presents challenges; leakage into the bulk could disrupt performance or negate the effect entirely. Maintaining perfect boundary conditions will prove difficult within any physical system, as real materials inevitably exhibit imperfections that can leak energy into unwanted areas. This approach establishes a new framework for scalable topological switches applicable in technologies such as photonic lattices or superconducting qubit arrays. The team demonstrated strong directional movement, or chiral transfer, of quantum information carried by topological edge states within a simplified structure, offering vital insight for experiments aiming to build chiral switches, devices directing energy flow, potentially launching a major era in topological photonics.

This research analytically determined the coordinates of exceptional points, specific conditions enabling control, within a Su-Schrieffer-Heeger chain. By tuning gain and loss at boundaries and encircling these points, researchers showed they could robustly transfer an edge state across the system with perfect fidelity or return it to its origin. The authors suggest this method is experimentally verifiable and controllable through boundary non-Hermitian driving.

👉 More information
🗞 Boundary exceptional point driven chiral switch of topological edge states
✍️ Bikashkali Midya and Barsa Rani Sahu (Indian Institute of Science Education and Research Berhampur)
🧠 ArXiv: https://arxiv.org/abs/2610.29316

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