We introduce an off-resonant coherent excitation scheme that realizes pronounced stationary inversion in a quantum dot - semiconductor cavity system. Exciton inversions of more than 0.25 are predicted over a wide range of experimentally-accessible parameters.
We present an off-resonant excitation scheme that realizes pronounced stationary inversion in a two level system. The created inversion exploits a cavity-assisted two-photon resonance to enhance the multiphoton regime of nonlinear cavity QED and survives even in a semiconductor environment, where the cavity decay rate is comparable to the cavity-dot coupling rate. Exciton populations of greater than 0.75 are obtained in the presence of realistic decays and pure dephasing. Quantum trajectory simulations and master equation calculations help elucidate the underlying physics and delineate the limitations of a simplified rate equation model. Experimental signatures of inversion and multiphoton cavity QED are predicted in the fluorescence intensity and second-order correlation function measured as a function of drive power.
We present a master equation approach to study the second-order quantum autocorrelation functions for up to two quantum-dot excitons, coupled to an off-resonant cavity in a semiconductor-single quantum-dot cavity system. For a single coupled off-resonant exciton, we observe unusual oscillatory behavior in the early time dynamics of the cavity autocorrelation function, which leads to decreased antibunching relative to the exciton mode. With a second coupled exciton in the system, we find that the magnitude and the lifetime of these oscillations greatly increases, since the cavity is then able to exchange photons with multiple excitonic resonances. These results demonstrate that for incoherent pumping, the ubiquitous two-level atom model completely breaks down and that multiple excitonic resonances act in concert to spoil the antibunching characteristics of the cavity quasimode. We connect these findings to a series of recent surprising experimental results for single quantum dot-semiconductor cavity systems, including photonic crystal systems and micropillar cavities.
Quantum optical phenomena are explored in artificial atoms well known as semiconductor quantum dots, in the presence of excitons and biexcitons. The analytical results are obtained using the conventional time-dependent perturbation technique. Numerical estimations are made for arealistic sample of CdS quantum dots in a high-Q cavity. Quantum optical phenomena such as quantum Rabi oscillations, photon statistics and collapse and revival of population inversion in exciton and biexciton states are observed. In the presence of biexcitons the collapse and revival phenomenon becomes faster due to the strong coupling of biexciton with cavity field.
We report on coherent resonant emission of the fundamental exciton state in a single semiconductor GaAs quantum dot. A resonant regime with picosecond laser excitation is realized by embedding the quantum dots in a one-dimensional waveguiding structure. As the pulse intensity is increased, Rabi oscillation is observed up to three periods. The Rabi regime is achieved owing to an enhanced light-matter coupling in the waveguide but with different dynamics with respect to usual cavity quantum electrodynamics. The resonant control of the quantum dot fundamental transition opens new possibilities in quantum state manipulation and quantum optics experiments in condensed-matter physics.
The dynamics of the entanglement for coherent excitonic states in the system of two, coupled, large semiconductor quantum dots ${(R/a}_{B}\ensuremath{\gg}1)$ mediated by a single-mode cavity field is investigated. Maximally entangled coherent excitonic states can be generated by cavity field initially prepared in odd coherent state. The entanglement of the excitonic coherent states between two dots reaches maximum when no photon is present in the cavity. The effects of the zero-temperature environment on the entanglement of excitonic coherent state are also studied using the concurrence for two subsystems of the excitons.