Nonclassical light emission from single self-assembled indium arsenide quantum dots

We describe quantum optical experiments using single self-assembled InAs quantum dots in photonic nanostructures. Even though cryogenic temperatures are required to observe their atom-like characteristics, absence of a trapping requirement renders quantum dots very useful in a number of experiments previously not demonstrated using atoms.; The inherit two-level nature of their single excitonic and biexcitonic transitions allow the observation of photon antibunching under continuous wave excitation. Under pulsed excitation conditions, the photon antibunching phenomenon gives rise to triggered single photon emission, provided that free-carriers have much shorter life-times than quantum dot ground state carriers. This new nonclassical light source. i.e. single photon turnstile device , promises applications in quantum cryptography, and quantum information processing.; We have observed weak coupling cavity quantum electrodynamics (cavitvy-QED) regime by tuning the single excitonic transition into resonance with a high quality factor microdisk whispering gallery mode. Such a coupling that resulted in the enhancement of spontaneous emission rate by at least 3.4, can be used in improving the collection efficiency of our single photon source.; Carrier-carrier interactions also bring additional richness to quantum dot physics allowing the observation of a stable cascade system (biexciton - single exciton cascade) and charged exciton phenomenon. We performed photon correlation measurements that demonstrated the cascaded emission and gave evidence for the identification of charged emission peaks. Photons emitted by the biexciton - single exciton cascade are also predicted to constitute a two-photon polarization entangled state, similar to the case in atomic cascades. Under nonresonant excitation conditions, we have not observed any polarization correlations; this is probably due to the short spin lifetimes of ground state carriers.; Finally we propose an experimental scheme for observing two-photon interference using the single quantum dot single photon source. Observation of two-photon interference from our single photon source can lead to free space quantum teleportation, and quantum information processing experiments. We demonstrate the results of linewidth measurements under nonresonant continuous wave and pulsed excitation conditions that revealed linewidths as small as 5.6 μ eV. The fact that the measured linewidths were ∼10 times larger than the transform limited values prevented us from observing two-photon interference.