Natural exceptional points in the excitation spectrum of a light–matter system

• DOI: 10.1364/optica.497170
• Publication Date: 2023-07-05T14:00:37Z
• Authors: A. Opala; M. Furman; M. Król; R. Mirek; K. Tyszka; B. Seredyński; W. Pacuski; J. Szczytko; M. Matuszewski; B. Piętka
• Keywords: Quantum Gases (cond-mat.quant-gas); FOS: Physical sciences; Condensed Matter - Quantum Gases; Physics - Optics; Optics (physics.optics)

In this work, we observe natural exceptional points in the excitation spectrum of an exciton–polariton system by optically tuning light–matter interactions. The observed do not require any spatial or polarization degrees freedom and result solely from transition weak to strong coupling. It was demonstrated that they coincide with threshold for photon lasing, confirming previous theoretical predictions [ Phys. Rev. Lett. 122 , 185301 ( 2019 ) PRLTAO 0031-9007 10.1103/PhysRevLett.122.185301 Optica 7 1015 2020 OPTIC8 2334-2536 10.1364/OPTICA.397378 ]. Using a technique where coherent laser pump induces up-converted excitations, encircle point parameter space coupling strength particle momentum. Our method local optical control paves way investigation fundamental phenomena, including dissipative phase transitions non-Hermitian topological states.