Experiment and analysis of an optical measurement of spin-flip lifetime of donor-bound electrons in n-GaAs

Abstract

Implementation of quantum communication requires material media that can store and process information. Recent studies have predicted that at low doping levels (<= 10e14cm(-3)) and low temperatures (<10K) semiconductors have long coherence times and are promising candidates for studying quantum information processing. Experimental research work has also found the spin- flip lifetime (T1) of n-GaAs to be of the order of a millisecond and has indicated the dependence of T1 on the optical pumping field. In this work, we perform preparatory experiments with an ensemble of lambda systems formed by donor-bound electrons in n-GaAs using a polarization maintaining confocal microscope setup in a He-bath cryostat. We describe in detail, the procedure for finding a homogeneous ensemble in a sample of GaAs:Si. This work aims towards an optical measurement and the characterization of the spin- ip lifetime of the donor-bound electrons, to determine the dependence on optical pumping parameters. We further describe a Fabry-Perot filter cavity that has been designed for the detection of weak Raman photons during the experiment. The design of the cavity has been modified and its performance has been improved and characterized for the purpose of this experiment.