The III-V nanowire quantum dots (NWQDs) monolithically grown on silicon substrates, combining the advantages of both one- and zero-dimensional materials, represent one of the most promising technologies for integrating advanced III-V photonic technologies on a silicon microelectronics platform. However, there are great challenges in the fabrication of high-quality III-V NWQDs by a bottom-up approach, that is, growth by the vapor-liquid-solid method, because of the potential contamination caused by external metal catalysts and the various types of interfacial defects introduced by self-catalyzed growth. Here, we report the defect-free self-catalyzed III-V NWQDs, GaAs quantum dots in GaAsP nanowires, on a silicon substrate with pure zinc blende structure for the first time. Well-resolved excitonic emission is observed with a narrow line width. These results pave the way toward on-chip III-V quantum information and photonic devices on silicon platform.

We report a "plug and play" single photon source, fully integrated with an optical fiber, emitting at 1.3 m. Micropillars were patterned on a single layer InAs quantum dot wafer to guarantee a single pillar per fiber core. The single exciton peak filtered with a tunable optical filter was fed to a Hanbury Brown and Twiss interferometer, and the second order correlation function at zero delay was less than 0.5, indicating single photon emission. The measured decay dynamics under double-pulse excitation show that the single photon device can be operated at speeds greater than 0.5 GHz. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2960549͔Single photon sources are in demand for quantum key distribution 1,2 and linear optical quantum computation. 3 Recently, investigations on single photon emission from semiconductor quantum dots ͑QDs͒ have concentrated on electrical pumping, 4-7 high repetition rates, 8 telecommunication wavelengths, 9-13 high temperature operation 14 and emission stability.15 From a practical point of view, it is desirable to have a "plug and play" type, stable single photon source at telecommunication wavelengths, ideally with a high repetition rate.In our previous work, 15 we have demonstrated a plug and play single photon source integrated with an optical fiber system. In this system, a bundle of single mode optical fibers ͑around 600͒ are bound together at one end and polished. The polished end of the fiber bundle is directly mounted on top of a 5 ϫ 5 mm 2 wafer with a very low quantum dot density. All fibers in the other end are free and can be connected to a wavelength division multiplexing ͑WDM͒ device with two separate output fibers. One of these two fibers ͑input fiber͒ carries the excitation light and the other ͑output fiber͒ carries the emitted light. The exciton emission collected from a single QD via one of the fibers in the fiber bundle exhibits single photon emission. Great stability of nearly ͑but not limited to͒ one month has been demonstrated. 15 However, the emission wavelength from InAs QD was around 920 nm. In this work, we realize a plug and play single photon source at telecommunication wavelengths using the same system. The repetition rate of this type of photon source can be higher than 0.5 GHz, which is confirmed with two-pulse lifetime measurements.The InAs QD wafer with a 1.3 m wavelength emission is grown by molecular-beam expitaxy with an InGaAs capping layer. The QD layer is embedded in a 1-lambda cavity between one-period ͑top͒ and 15-period ͑bottom͒ GaAs/ Al 0.9 Ga 0.1 As distributed Bragg reflectors, in order to enhance the extraction efficiency. The collection efficiency of the fiber with a numerical aperture of 0.12 was 0.69%, calculated with the method described in Ref. 16. To achieve very low QD density ͑around 2 ϫ 10 8 dots/ cm 2 ͒, an ultralow growth rate was used for the sample growth.17 With this growth technique, single photon emission at 1.3 m was demonstrated using a confocal system with either InGaAs ͑Ref. 18͒ or superconducting single-photon d...

*These authors contributed equally to this work. AbstractCavities embedded in photonic crystal waveguides offer a promising route towards large scale integration of coupled resonators for quantum electrodynamics applications. In this letter, we demonstrate a strongly coupled system formed by a single quantum dot and such a photonic crystal cavity. The resonance originating from the cavity is clearly identified from the photoluminescence mapping of the out-of-plane scattered signal along the photonic crystal waveguide. The quantum dot exciton is tuned towards the cavity mode by temperature control. A vacuum Rabi splitting of ~ 140 μeV is observed at resonance.

Temperature dependence of the photoluminescence properties of self-assembled In Ga As ∕ Ga As single quantum dot

We present bias-dependent micro-photoluminescence (μ-PL) spectroscopy of the neutral (X 0) and singly negatively-charged (X −) excitons in single InAs/GaAs self-assembled quantum dots (QDs) embedded in the intrinsic region of an n-i-Schottky diode based on a two-dimensional electron gas (2DEG), which was obtained from a Si δ-doped GaAs layer. Using such a device structure, we demonstrate bias-controlled single-electron charging of a single QD as the QD s-shell electron state is tuned below the Fermi level. This is verified experimentally by the sequential appearance of energetically-distinct PL emission lines from the two excitons and supported by theoretical calculations. In addition, it is shown both experimentally and theoretically that simultaneous PL emission from the X 0 and X − excitons within a particular bias range is the result of a long-lived charge-nonequilibrium state due to weak tunnel-coupling between the QDs and 2DEG in our device. Further, the ability to tune the exciton transition energies via the quantum-confined Stark effect is observed, offering insight into the carrier wave function distributions in the QD and the QD material structure. Finally, we propose a number of spintronic device concepts that may be made feasible as a result of this investigation into bias-controlled carrier tunneling between a self-assembled QD and a 2DEG.