Chiral Modes at Exceptional Points in Exciton-Polariton Quantum Fluids

• Main Authors: Gao, T., Li, G., Estrecho, E., Liew, Timothy Chi Hin, Comber-Todd, D., Nalitov, A., Steger, M., West, K., Pfeiffer, L., Snoke, D. W., Kavokin, A. V., Truscott, A. G., Ostrovskaya, E. A.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2018
• Subjects: Exciton Polariton; Bose-Einstein Condensates
• Online Access: https://hdl.handle.net/10356/88307; http://hdl.handle.net/10220/44589
• Institution: Nanyang Technological University

We demonstrate the generation of chiral modes–vortex flows with fixed handedness in exciton-polariton quantum fluids. The chiral modes arise in the vicinity of exceptional points (non-Hermitian spectral degeneracies) in an optically induced resonator for exciton polaritons. In particular, a vortex is generated by driving two dipole modes of the non-Hermitian ring resonator into degeneracy. Transition through the exceptional point in the space of the system’s parameters is enabled by precise manipulation of real and imaginary parts of the closed-wall potential forming the resonator. As the system is driven to the vicinity of the exceptional point, we observe the formation of a vortex state with a fixed orbital angular momentum (topological charge). This method can be extended to generate higher-order orbital angular momentum states through coalescence of multiple non-Hermitian spectral degeneracies. Our Letter demonstrates the possibility of exploiting nontrivial and counterintuitive properties of waves near exceptional points in macroscopic quantum systems.