PhD Project
Honours Project
Dr Marcelo de Almeida


The major roadblock for optical quantum information technologies is the absence of reliable single- and entangled- photons sources. The standard technique to generate such states employ the photons generated by spontaneous parametric down-conversion, where a strong laser beam interacts with a nonlinear crystal, generating pairs of photons. However, down-conversion is an intrinsically random process, meaning it generates a large component of vacuum--i.e., most of the time no photons a generates--as well as multi-photons contributions--i.e. more than two photons can be generated per pair. Consequently, only a low number of single- and entangled photons cane be effective extracted, and they are in general unavoidably contaminated by multiple photons emissions. 


This project will demonstrate that remove the photons source road block is possible and will develop the next generation of low noise, as well as efficient sources of single and entangled photons suitable for application in quantum information. The specific aims are:


1-Develop solid state based single-photon source: Here we will develop single-photons source based on semiconductor quantum dots embedded in pillar micro-cavities. Our goal is to produce a prototype of a 4-fold, capable of multiplex single photons into 4 different spatial modes, with brightness 3 order-of-magnitude higher than current best technology. 


2-Develop heralded single- and entangled photon sources: Current single- and entangled- photon sources are not heralded, i.e., the photons arrive randomly, without no timing information and are highly contaminated by multi-photon events. Here we will demonstrate generation of heralded single and entangled photon states using  correlated photons produced by semiconductor quantum dots embedded in double pillar micro-cavities.