Cooperative recombination of electron-hole pairs in semiconductor quantum wells under quantizing magnetic fields

We present results of detailed investigations of light emission from semiconductor multiple quantum wells at low temperatures and high magnetic fields excited by intense femtosecond laser pulses. The intensity and linewidth as well as the directional and statistical properties of photoemission strongly depended on the magnetic field strength and pump laser fluence. We also investigated the effects of spot size, temperature, excitation geometry, and excitation pulse width on the emission properties. The results suggest that the initially incoherent photoexcited electron-hole pairs spontaneously form a macroscopic coherent state upon relaxation into the low-lying magnetoexcitonic states, followed by the emission of a superfluorescent burst of radiation. We have developed a theoretical model for superfluorescent emission from semiconductor quantum wells, which successfully explained the observed characteristics.