Observation of a chiral state in a microwave cavity. Experimental demonstration of a coherent perfect absorber with PT phase transition. Loss-induced suppression and revival of lasing. Observation of PT-symmetry breaking in complex optical potentials. Creation of orbital angular momentum states with chiral polaritonic lenses. All-optical control of the quantum flow of a polariton condensate. Sculpting oscillators with light within a nonlinear quantum fluid. Coupling and level repulsion in the localized regime: from isolated to quasiextended modes. Random-matrix theories in quantum physics: common concepts. Quantizing a classically ergodic system: Sinai’s billiard and the KKR method. Off-branch polaritons and multiple scattering in semiconductor microcavities. Making sense of non-Hermitian Hamiltonians. Non-Hermitian Quantum Mechanics (Cambridge Univ. Exciton-polariton Bose–Einstein condensation. Bose–Einstein condensation of exciton polaritons. Our findings pave the way to studies of non-Hermitian quantum dynamics of exciton-polaritons, which may uncover novel operating principles for polariton-based devices. We also observe mode switching and a topological Berry phase for a parameter loop encircling the exceptional point 23, 24. By varying parameters of the billiard, we observe crossing and anti-crossing of energy levels and reveal the non-trivial topological modal structure exclusive to non-Hermitian systems 9, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22. Such points can cause remarkable wave phenomena, such as unidirectional transport 15, anomalous lasing/absorption 16, 17 and chiral modes 18. Eigenmodes of this billiard exhibit multiple non-Hermitian spectral degeneracies, known as exceptional points 13, 14. Using a spatially structured optical pump 10, 11, 12, we create a chaotic exciton-polariton billiard-a two-dimensional area enclosed by a curved potential barrier. Here we demonstrate that non-Hermiticity dramatically modifies the structure of modes and spectral degeneracies in exciton-polariton systems, and, therefore, will affect their quantum transport, localization and dynamical properties 7, 8, 9. However, the inherent non-Hermitian nature of this potential has so far been largely ignored in exciton-polariton physics. Thus, the exciton-polaritons always exist in a balanced potential landscape of gain and loss. Importantly, exciton-polaritons are a profoundly open (that is, non-Hermitian 4, 5) quantum system, which requires constant pumping of energy and continuously decays, releasing coherent radiation 6. They have emerged as a robust solid-state platform for next-generation optoelectronic applications as well as for fundamental studies of quantum many-body physics. Exciton-polaritons are hybrid light–matter quasiparticles formed by strongly interacting photons and excitons (electron–hole pairs) in semiconductor microcavities 1, 2, 3.
0 Comments
Leave a Reply. |