Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Nat Commun. 2013;4:2335. doi: 10.1038/ncomms3335.
Dipolar excitons are long-lived quasi-particle excitations in semiconductor heterostructure that carry an electric dipole. Cold dipolar excitons are expected to have new quantum and classical multi-particle correlation regimes, as well as several collective phases, resulting from the intricate interplay between the many-body interactions and their quantum nature. Here we show experimental evidence of a few correlation regimes of a cold dipolar exciton fluid, created optically in a semiconductor bilayer heterostructure. In the higher temperature regime, the average interaction energy between the particles shows a surprising temperature dependence, which is evidence for correlations beyond the mean field model. At a lower temperature, there is a sharp increase in the interaction energy of optically active excitons, accompanied by a strong reduction in their apparent population. This is evidence for a sharp macroscopic transition to a dark state, as has been suggested theoretically.
偶极激子是半导体异质结构中长寿命的准粒子激发，带有电偶极矩。冷偶极激子预计会有新的量子和经典多粒子关联态，以及几个集体相，这是由多体相互作用及其量子性质的复杂相互作用产生的。在这里，我们展示了在半导体双层异质结构中光学产生的冷偶极激子流体的几个关联态的实验证据。在较高的温度范围内，粒子之间的平均相互作用能显示出令人惊讶的温度依赖性，这表明存在超越平均场模型的关联。在较低的温度下，光活性激子的相互作用能急剧增加，同时它们的表观种群明显减少。这是向暗态的宏观跃迁的证据，这在理论上已经被提出。
