Some Optical Properties Of Tunneling Quantum Dot Molecules

In this dissertation,We investigated the optical properties of tunneling quantum dot molecules.Firstly,based on the full quantum theory,We studied the Wigner-Yanase skew information of a tunneling quantum dot molecule interacting with a single-mode laser field.We investigated the time evolution of population on each energy level of the quantum dot molecule,and coupling parameters’ effect on the skew information.And We also checked the effects of the average photon number ?n?,detuning Δ and coupling parameter λ on the Wiger-Yanase skew information.We found collapses and revivals of the population oscillations on different energy level.The collapse time will increase if the coupling parameter λ increases.The skew information evolution period will increase with the average photon number ?n?.The amount of detuning will affect the number of oscillations of the skew information in the population oscillation collapse time regions.Secondly,We also discussed the possibility of the optical bistability in the three energy level tunneling quantum dots.By solving the optical response equation of the system,We conclude that under some conditions,optical stability can be realized in the tunneling quantum dots.We investigated all the parameters’ effect on optical bistability in this system.Thirdly,We studied the possibility of superluminal and subluminal phenomena in tunneling quantum dot molecules.Using electromagnetically induced transparency technology,the dispersion relation of the medium can be regulated.Based on the Hamiltonian of the tunnel quantum dot and density matrix equations,the steady-state solution of the density matrix equation is obtained.We derived the group refractive index and absorption coefficient of the excited medium based on the steady-state solution of the system.Group refractive index and absorption coefficient are two key physical quantities of the medium.By observing these two quantities,the condition for the superluminal or subluminal light to exist can be obtained.Finally,We explored the field squeezing effect in a tunneling-coupled quantum dot molecule driven by a quantized field and a static gate electric field where the direct and indirect excitonic states are coupled by tunneling.The field squeezing parameters for two qudrature variance are calculated by numerically solving the Liouville-von Neumann-Lindblad equation considering the spontaneous exciton decay and pure dephasing as decoherence channels in an initial coherent field.We found field squeezing in short interaction time region and during the population oscillation revivals.And We also found that the squeezing during the revivals can be enhanced by decreasing of the dissipation parameters and by increasing of the initial mean photon numbers,tunneling coefficient and dissipative parameter under certain conditions,while there is little or no change in the short time region.