Quantum-Spectroscopy Studies on Semiconductor Nanostructures

Quantum spectroscopy utilizes the quantum fluctuations of the light source to characterize and control matter. More specifically, desired many-body states can be directly excited to the semiconductor by adjusting light source's quantum fluctuations. The method is experimentally realizable by projecting an extensive set of classical measurements into a quantum-optical response resulting from any possible quantum source. In this work, quantum spectroscopy is used to identify new classes of many-body states and quantum processes in semiconductor nanostructures. In the first part of this Thesis, the optical properties of semiconductor quantum wells are analyzed with quantum spectroscopy by projecting high-precision optical measurements into quantum-optical responses. It is shown that quantum spectroscopy can characterize the properties of specific stable electron-hole cluster – called quasiparticles – much more sensitively than traditional ultrafast laser spectroscopy. In particular, unambiguous evidence is demonstrated for the identification of a new highly correlated quasiparticle in direct-gap Galliumarsenide quantum wells, the dropleton, that is a quantum droplet consisting of four-to-seven electron-hole pairs. To determine the detectable excitation energetics of such correlated quasiparticles in optically excited semiconductor quantum wells, a new theoretical framework is presented which allows for the computation of the excitation spectrum based on a pair-correlation function formulation of the quasiparticle state. Another study in this Thesis deals with the emission properties of optically pumped quantum-dot microcavities. Experimental and theoretical evidence is shown for a new intriguing quantum-memory effect that is controllable by adjusting pump source's quantum fluctuations. The last part of this Thesis presents a fundamental study about the general applicability of quantum spectroscopy in dissipative systems