Publication Date:
2015-10-13
Description:
Exciton-polaritons are hybrid light-matter quasiparticles formed by strongly interacting photons and excitons (electron-hole pairs) in semiconductor microcavities. 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. Importantly, exciton-polaritons are a profoundly open (that is, non-Hermitian) quantum system, which requires constant pumping of energy and continuously decays, releasing coherent radiation. Thus, the exciton-polaritons always exist in a balanced potential landscape of gain and loss. However, the inherent non-Hermitian nature of this potential has so far been largely ignored in exciton-polariton physics. 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. Using a spatially structured optical pump, we create a chaotic exciton-polariton billiard--a two-dimensional area enclosed by a curved potential barrier. Eigenmodes of this billiard exhibit multiple non-Hermitian spectral degeneracies, known as exceptional points. Such points can cause remarkable wave phenomena, such as unidirectional transport, anomalous lasing/absorption and chiral modes. 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. We also observe mode switching and a topological Berry phase for a parameter loop encircling the exceptional point. 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gao, T -- Estrecho, E -- Bliokh, K Y -- Liew, T C H -- Fraser, M D -- Brodbeck, S -- Kamp, M -- Schneider, C -- Hofling, S -- Yamamoto, Y -- Nori, F -- Kivshar, Y S -- Truscott, A G -- Dall, R G -- Ostrovskaya, E A -- England -- Nature. 2015 Oct 22;526(7574):554-8. doi: 10.1038/nature15522. Epub 2015 Oct 12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 2601, Australia. ; Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198, Japan. ; School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore. ; Technische Physik and Wilhelm-Conrad-Rontgen Research Center for Complex Material Systems, Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany. ; SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK. ; ImPACT Project, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan. ; Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305-4085, USA. ; Physics Department, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26458102" target="_blank"〉PubMed〈/a〉
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
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Chemistry and Pharmacology
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Medicine
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Natural Sciences in General
,
Physics
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