Kim, Ji-HeeNoe, G. Timothy IIMcGill, Stephen A.Wang, YongruiWojcik, Aleksander K.Belyanin, Alexey A.Kono, Junichiro2013-12-192013-12-192013Kim, Ji-Hee, Noe, G. Timothy II, McGill, Stephen A., et al.. "Fermi-edge superfluorescence from a quantum-degenerate electron-hole gas." <i>Scientific Reports,</i> 3, (2013) Nature Publishing Group: http://dx.doi.org/10.1038/srep03283.https://hdl.handle.net/1911/75255Nonequilibrium can be a source of order. This rather counterintuitive statement has been proven to be true through a variety of fluctuation-driven, self-organization behaviors exhibited by out-of-equilibrium, many-body systems in nature (physical, chemical, and biological), resulting in the spontaneous appearance of macroscopic coherence. Here, we report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence (SF), which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary SF, making electron-hole SF even more ﾑﾑsuperﾒﾒ than atomic SF.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1038/srep03283