Experimental Simulation of Symmetry-Protected Higher-Order Exceptional Points with Single Photons

Abstract

Exceptional points (EPs) of non-Hermitian (NH) systems have recently attracted increasing attention due to their rich phenomenology and intriguing applications. Compared to the predominantly studied second-order EPs, higher-order EPs have been assumed to play a much less prominent role because they generically require the tuning of more parameters. Here we experimentally simulate two-dimensional topological NH band structures using single-photon interferometry, and observe topologically stable third-order EPs obtained by tuning only two real parameters in the presence of symmetry. In particular, we explore how different symmetries stabilize qualitatively different third-order EPs: the parity-time symmetry leads to a generic cube-root dispersion, while a generalized chiral symmetry implies a square-root dispersion coexisting with a flat band. Additionally, we simulate fourfold degeneracies, composed of the non-defective twofold degeneracies and second-order EPs. Our work reveals the abundant and conceptually richer higher-order EPs protected by symmetries and offers a versatile platform for further research on topological NH systems.

arXiv comment15 pages, 9 figures

References in corpus (26)

• Unidirectional Invisibility induced by PT-Symmetric Periodic Structures
• Loss-induced suppression and revival of lasing
• Topological energy transfer in an optomechanical system with exceptional points
• Enhanced sensitivity operation of an optical gyroscope near an exceptional point
• Observation of parity-time symmetry breaking in a single spin system
• Observation of coherent perfect absorption at an exceptional point
• Experimental realization of a Weyl exceptional ring
• Exceptional rings in two-dimensional correlated systems with chiral symmetry
• Symmetry-protected nodal phases in non-Hermitian systems
• Topological exceptional surfaces in non-Hermitian systems with parity-time and parity-particle-hole symmetries
• Symmetry and Higher-Order Exceptional Points
• Exceptional Surfaces in PT-Symmetric Photonic Systems
• Non-Hermitian Hopf-Link Exceptional Line Semimetals
• Symmetry-protected multifold exceptional points and their topological characterization
• Knotted Non-Hermitian Metals
• Fermion doubling theorems in 2D non-Hermitian systems for Fermi points and exceptional points
• Quantum sensing with a single-qubit pseudo-Hermitian system
• A Classification of Non-Hermitian Random Matrices
• Simulating Exceptional Non-Hermitian Metals with Single-Photon Interferometry
• Exceptional precision of a nonlinear optical sensor at a square-root singularity
• Direct Measurement of Topological Properties of an Exceptional Parabola
• Quantum optical realization of arbitrary linear transformations allowing for loss and gain
• Non-Hermitian adiabatic transport in spaces of exceptional points
• Optimal experimental demonstration of error-tolerant quantum witnesses
• Symmetry-protected exceptional and nodal points in non-Hermitian systems
• Two-qutrit Entanglement Witnesses and Gell-Mann Matrices

Cited by in corpus (11)

• Homotopy, Symmetry, and Non-Hermitian Band Topology
• Quantum tomography of a third-order exceptional point in a dissipative trapped ion
• Braids and Higher-order Exceptional Points from the Interplay Between Lossy Defects and Topological Boundary States
• Fractal Nodal Band Structures
• Nodal phases in non-Hermitian wallpaper crystals
• Winding Topology of Multifold Exceptional Points
• Observation of Braid-Protected Unpaired Exceptional Points
• Topological Dynamics and Correspondences in Composite Exceptional Rings
• Topological Engineering of High-Order Exceptional Points through Transformation Optics
• Arbitrary-Order Scattering Exceptional Points in Configurable Non-Hermitian Zero-Index Materials
• The analytically tractable zoo of similarity-induced exceptional structures