Resonant nonlinear interaction of light in photonic crystal cavity-quantum dot systems (PhD)

Abstract

The work presented in this thesis concerns cavity quantum electrodynamics techniques for generatingthephotonpairsandentangledstatesusingthequantumdotsandphotoniccavities for quantum information applications, such as quantum computation, quantum teleportation, and quantum cryptography. We have presented the schemes to realize a highly efficient solid state source of photon pairs, cooperative emission of two photons, and generation of entangled states. For highly efficient solid state source of photon pairs, a semiconductor quantum dot is embedded in a photoniccrystalmicrocavityandiscoherentlypumpedfromitsgroundstateusingaGaussian pulse and a continuous wave laser which makes it innovative. The photon pair emission takes place either by four wave-mixing process (FWM) or by stimulated Raman adiabatic passage (STIRAP) depending on the applied continuous wave laser between exciton and biexciton state. The efficiency of generating the photon pair by FWM is higher than 0.9 and by STIRAP process is around 0.77. For cooperative two photon emission, two quantum dots are coupled with a single mode and two mode photonic crystal cavity. The cooperative two photon emission occurs when excitons in two off-resonantly coupled quantum dots decay simultaneously. Also, we bring out the role of exciton- phonon coupling on two-photon cooperative emission. The interaction of two quantum dots with common cavity fields leads to cavity induced two-photon emission which is strongly inhibited by electron phonon coupling. The interaction with common phonon bath produces phonon induced two-photon emission. For generating entangled states, a quantum dot in a bimodal cavity is prepared in the biexciton state. The cascaded biexciton-exciton decay of quantum dot produces either a two photon NOON state or a polarization entangled state. We also study the effect of phonon coupling on the generated entangled states. We find that the concurrence which measures the entanglement decreases on increasing the temperature in both cases.