Related Experiment Video
Updated: Jul 12, 2025
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
10.0K
Realization and topological properties of third-order exceptional lines embedded in exceptional surfaces
Weiyuan Tang1,2, Kun Ding3, Guancong Ma4
1Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Nature Communications
|October 20, 2023
Summary
Researchers experimentally created order-3 exceptional lines (EL3) within order-2 exceptional surfaces (ES2). A novel winding number method successfully detects EL3 topology, enabling prediction of their behavior under perturbations.
Area of Science:
- Non-Hermitian physics
- Topological materials science
- Synthetic dimensions
Background:
- Hermitian nodal structures have well-defined topological properties.
- Exceptional points (EPs) and exceptional lines (ELs) in non-Hermitian systems exhibit unique spectral topology.
- Existing topological characterization methods struggle with complex exceptional geometries.
Purpose of the Study:
- To experimentally realize and characterize higher-order exceptional geometries.
- To develop a novel method for diagnosing the topology of embedded exceptional lines.
- To explore the potential for new non-Hermitian topological applications.
Main Methods:
- Experimental realization of order-3 exceptional lines (EL3) embedded in order-2 exceptional surfaces (ES2) in a 3D synthetic momentum space.
- Development and application of a resultant winding number method for topological characterization.
- Analysis of the connection between resultant intersection multiplicity and winding number.
Main Results:
- Successful experimental creation of EL3 within ES2.
- Demonstration of a winding number method capable of selectively detecting EL3 topology, distinct from the surrounding ES2.
- Prediction of EL3 evolution under perturbations based on diagnosed topological currents.
- Generalization of the approach for higher-order EPs.
Conclusions:
- Higher-order exceptional geometries possess unprecedented topological properties.
- The resultant winding number offers a powerful tool for diagnosing and characterizing non-Hermitian topology.
- This work paves the way for novel non-Hermitian topological devices and applications.
Related Concept Videos
01:29Equipotential Surfaces and Field Lines
3.8K
Electric potential can be pictorially represented as a three-dimensional surface. On such a surface, the electric potential is constant everywhere. The equipotential surface is always perpendicular to the electric field lines, and while it is three-dimensional, it can be treated as an equipotential line in a two-dimensional case. These equipotential lines are also always perpendicular to electric field lines. The term equipotential is often used as a noun, referring to an equipotential line or...
3.8K
01:16Second Uniqueness Theorem
1.0K
Consider a region consisting of several individual conductors with a definite charge density in the region between these conductors. The second uniqueness theorem states that if the total charge on each conductor and the charge density in the in-between region are known, then the electric field can be uniquely determined.
In contrast, consider that the electric field is non-unique and apply Gauss's law in divergence form in the region between the conductors and the integral form to the...
In contrast, consider that the electric field is non-unique and apply Gauss's law in divergence form in the region between the conductors and the integral form to the...
1.0K
01:16Equipotential Surfaces and Conductors
3.5K
For a conductor in which all charges are at rest, the conductor's surface is equipotential. The electric field is always perpendicular to equipotential surfaces. Therefore, in a conductor with static charges, the electric field just outside the conductor is always perpendicular to the conductor's surface. Any tangential component of the electric field will cause charges to move inside the conductor, which will violate the electrostatic nature of the system. In an electrostatic...
3.5K
01:05Properties of the Root Locus
117
The root locus method is an invaluable tool for analyzing higher-order systems without needing to factor the denominator of the transfer function. A pole of the system is identified when the characteristic polynomial in the transfer function's denominator equals zero.
To determine if a point lies on the root locus, the criterion involves the sum of angles contributed by all poles and zeros to that point. Specifically, this sum must be an odd multiple of 180 degrees. The gain at any point on...
To determine if a point lies on the root locus, the criterion involves the sum of angles contributed by all poles and zeros to that point. Specifically, this sum must be an odd multiple of 180 degrees. The gain at any point on...
117
01:17Moment-Area Theorems
263
The Moment-Area Theorem is crucial in structural engineering for analyzing beam bending, particularly in applications like building floor supports. This theorem utilizes the geometric properties of the elastic curve, which depicts how a beam deforms under load, to simplify the calculations of deflections and slopes.
The theorem is divided into two parts. The first part connects the angle between tangents at any two points on the beam's elastic curve to the area under a curve derived by...
The theorem is divided into two parts. The first part connects the angle between tangents at any two points on the beam's elastic curve to the area under a curve derived by...
263
01:27Gauss's Law: Planar Symmetry
8.0K
A planar symmetry of charge density is obtained when charges are uniformly spread over a large flat surface. In planar symmetry, all points in a plane parallel to the plane of charge are identical with respect to the charges. Suppose the plane of the charge distribution is the xy-plane, and the electric field at a space point P with coordinates (x, y, z) is to be determined. Since the charge density is the same at all (x, y) - coordinates in the z = 0 plane, by symmetry, the electric field at P...
8.0K