Jiang Jian-Hua, John Sajeev
Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 Canada.
Sci Rep. 2014 Dec 11;4:7432. doi: 10.1038/srep07432.
Semiconductor-microcavity polaritons are composite quasiparticles of excitons and photons, emerging in the strong coupling regime. As quantum superpositions of matter and light, polaritons have much stronger interparticle interactions compared with photons, enabling rapid equilibration and Bose-Einstein condensation (BEC). Current realizations based on 1D photonic structures, such as Fabry-Pérot microcavities, have limited light-trapping ability resulting in picosecond polariton lifetime. We demonstrate, theoretically, above-room-temperature (up to 590 K) BEC of long-lived polaritons in MoSe2 monolayers sandwiched by simple TiO2 based 3D photonic band gap (PBG) materials. The 3D PBG induces very strong coupling of 40 meV (Rabi splitting of 62 meV) for as few as three dichalcogenide monolayers. Strong light-trapping in the 3D PBG enables the long-lived polariton superfluid to be robust against fabrication-induced disorder and exciton line-broadening.
半导体微腔极化激元是激子和光子的复合准粒子，出现在强耦合 regime 中。作为物质和光的量子叠加态，极化激元与光子相比具有更强的粒子间相互作用，能够实现快速平衡和玻色 - 爱因斯坦凝聚（BEC）。目前基于一维光子结构（如法布里 - 珀罗微腔）的实现方式，其光捕获能力有限，导致极化激元寿命仅为皮秒级。我们从理论上证明，在由简单的基于 TiO₂ 的三维光子带隙（PBG）材料夹着的 MoSe₂ 单层中，存在高于室温（高达 590 K）的长寿命极化激元的 BEC。这种三维 PBG 对于仅三层二硫属化物单层就能诱导出高达 40 meV 的非常强的耦合（拉比分裂为 62 meV）。三维 PBG 中的强光捕获使得长寿命极化激元超流体能够抵抗制造过程中引入的无序和激子线宽展宽。
