We demonstrate an on-demand single-photon source that is compatible with standard telecom optical fiber. Through careful control of the critical strains of InAs∕GaAs self-assembled quantum dots, we produce a microcavity sample with a low density of large dots emitting into the fiber-optic transmission band at 1.3μm. The second-order correlation function of the source reveals a strong suppression in the rate of multiphoton pulses at both 5K and above 30K. The source may be useful for fiber-optic-based single-photon applications, such as quantum metrology, quantum communications, and distributed quantum computing.
Electrically injected InGaAs/GaAs quantum-dot microcavity light-emitting diode operating at 1.3 μm and grown by metalorganic chemical vapor depositionWe show that a planar semiconductor cavity can be used to enhance by a factor of ten the efficiency with which photons are collected from an electrically driven single InAs/ GaAs quantum dot. Under a fixed bias we observe that the photon statistics change when the injection current is modified. The observed bunching of photons from the biexciton state can be explained by the presence of charged states or dark states within the quantum dot with lifetimes greater than 4 ns. Single-photon emission from both the exciton and biexciton states is demonstrated under pulsed electrical injection.
We demonstrate that single photons can be generated from single InAs/GaAs quantum dots in photolithographically defined pillar microcavities. Pillars with a 1.9 microm diameter cavity show a four fold enhancement in the radiative decay rate due to the Purcell effect and a photon collection efficiency into a lens of up to 10%. Measurements of the second order correlation function reveal a greater than fifty fold reduction in the multi-photon emission rate compared to a laser of the same intensity.
One- and two-photon interference visibilities observed with the exciton emission from a quantum dot microcavity single-photon source are sensitive to the excitation conditions. In particular, the coherence time of the source is reduced with increasing pump power or excitation of the barrier layers. Furthermore, the two-photon interference visibility is affected by a long lived population of the biexciton state in the dot. This suggests that two-photon interference may be improved by controlling the exciton dynamics in the dot or by improved temporal resolution of the detection set-up.
We report that with appropriate voltage biasing it is possible to reduce the uncertainty in the time at which photons are emitted from a single quantum dot by an arbitrary factor. Using a resonant cavity light-emitting diode, we reduce the photon emission time jitter to one-fifth of the radiative lifetime. This enables us to demonstrate single-photon emission at a repetition rate of 1.07 GHz from both the exciton and biexciton states. This idea may lead to a new method by which pairs of indistinguishable photons can be generated for photonic quantum logic experiments.
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