QUANTUM PANCAKES FOR QUANTUM ENTANGLEMENT

University Of Arizona, Tucson AZ

Investigators

Abstract

9988865 Khitrova Quantum entanglement is essential for quantum repeaters needed for any of the proposals for quantum information processing to have a chance. The goal of this project is to obtain a quantum pancake that is good enough to achieve quantum entanglement. "Good" means one with a large dipole moment and radiatively dominated lifetime and decoherence time. A large dipole moment allows one to optically control the pancake with the vacuum field or an applied optical pulse faster than nonradiative decoherence times. Based on the growth of narrow-linewidth InGaAs/GaAs quantum wells and extraction of the radiative width and dipole moment, this proposal would take the next step: make a quantum pancake by laterally confining a 100- to 200-nm diameter portion of such a quantum well. A good pancake could be used in a small 3D microcavity to achieve quantum entanglement between a transition of the pancake and the optical mode. The approach will begin with a search for the best portions of a single quantum well with 0.8-micron spatial resolution using conventional optics or 0.25-micron resolution with a solid immersion lens. Various techniques for lateral confinement will be considered, for example, stress from a layer of self-organized dots grown above the quantum well or interdiffusion by local heating using a tightly focused laser beam. Candidate pancakes will be evaluated by a multitude of optical spectroscopic techniques. Differential reflectivity or absorption will determine the integrated absorption and dipole moment. MHz-resolution cw nonlinear spectroscopy and picosecond pump-probe measurements will be used to find out the effect of absorption of a single photon. Finally, streak-camera detection of the forward or backward emission following picosecond resonant excitation will show to what extent the polarization decay is purely radiative.