1] IBM Research-Zurich, Säumerstrasse 4, Rüschlikon 8803, Switzerland [2].
IBM Research-Zurich, Säumerstrasse 4, Rüschlikon 8803, Switzerland.
Nat Mater. 2014 Mar;13(3):247-52. doi: 10.1038/nmat3825. Epub 2013 Dec 8.
A Bose-Einstein condensate (BEC) is a state of matter in which extensive collective coherence leads to intriguing macroscopic quantum phenomena. In crystalline semiconductor microcavities, bosonic quasiparticles, known as exciton-polaritons, can be created through strong coupling between bound electron-hole pairs and the photon field. Recently, a non-equilibrium BEC (ref. ) and superfluidity have been demonstrated in such structures. With organic crystals grown inside dielectric microcavities, signatures of polariton lasing have been observed. However, owing to the deleterious effects of disorder and material imperfection on the condensed phase, only crystalline materials of the highest quality have been used until now. Here we demonstrate non-equilibrium BEC of exciton-polaritons in a polymer-filled microcavity at room temperature. We observe thermalization of polaritons and, above a critical excitation density, clear evidence of condensation at zero in-plane momentum, namely nonlinear behaviour, blueshifted emission and long-range coherence. The key signatures distinguishing the behaviour from conventional photon lasing are presented. As no crystal growth is involved, our approach radically reduces the complexity of experiments to investigate BEC physics and paves the way for a new generation of opto-electronic devices, taking advantage of the processability and flexibility of polymers.
玻色-爱因斯坦凝聚态（BEC）是一种物质状态，其中广泛的集体相干性导致了有趣的宏观量子现象。在晶体半导体微腔中，可以通过束缚电子-空穴对和光子场之间的强耦合来产生玻色准粒子，称为激子极化激元。最近，在这种结构中已经证明了非平衡 BEC（参考文献）和超流性。在介电微腔中生长的有机晶体已经观察到极化激元激光的特征。然而，由于无序和材料不完美对凝聚相的有害影响，迄今为止仅使用了最高质量的晶体材料。在这里，我们在室温下的聚合物填充微腔中演示了激子极化激元的非平衡 BEC。我们观察到极化激子的热化，并且在临界激发密度以上，在零面内动量处有明显的凝聚证据，即非线性行为、蓝移发射和长程相干性。呈现了区分行为与传统光子激光的关键特征。由于不涉及晶体生长，我们的方法极大地降低了研究 BEC 物理的实验复杂性，并为利用聚合物的可加工性和灵活性的新一代光电设备铺平了道路。
