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Proceedings Paper

Quantum key distribution using a semiconductor quantum dot source emitting at a telecommunication wavelength
Author(s): P. M. Intallura; M. B. Ward; O. Z. Karimov; Z. L. Yuan; P. See; A. J. Shields; P. Atkinson; D. A. Ritchie
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Paper Abstract

We present the first demonstration of telecom fiber-based quantum key distribution using single photons from a quantum dot in a pillar microcavity. The source offers both telecommunication wavelength operation at 1.3 microns and Purcell enhancement of the spontaneous emission rate. Several emission lines from the InAs/GaAs quantum dot are identified, including the exciton-biexciton cascade and charged excitonic emission. We show an order of magnitude increase in the collected intensity of the emission from a charged excitonic state when temperature tuned onto resonance with the HE11 mode of the pillar microcavity, as compared to the off-resonance intensity. Above- and below-GaAs-bandgap optical excitation was used and the effect of the excitation energy on the photoluminescence investigated. Exciting below the GaAs-bandgap offers significant improvement in the quality of the single photon emission and a reduction of the multi-photon probability to 0.1 times the value for Poissonian light was measured, before subtraction of detector dark counts, the lowest value recorded to date for a quantum dot source at a fibre wavelength. We observe also the first evidence of Purcell enhancement of the spontaneous emission rate for a single telecommunication wavelength quantum dot in a pillar microcavity. We have incorporated the source into a phase encoded interferometric scheme implementing the BB84 quantum cryptography protocol and distributed a key, secure from the pulse splitting attack, over standard telecommunication optical fibre. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at 1310 nm in the same system.

Paper Details

Date Published: 11 February 2008
PDF: 10 pages
Proc. SPIE 6902, Quantum Dots, Particles, and Nanoclusters V, 69020G (11 February 2008); doi: 10.1117/12.763412
Show Author Affiliations
P. M. Intallura, Toshiba Research Europe, Ltd. (United Kingdom)
Univ. of Cambridge (United Kingdom)
M. B. Ward, Toshiba Research Europe, Ltd. (United Kingdom)
O. Z. Karimov, Toshiba Research Europe, Ltd. (United Kingdom)
Z. L. Yuan, Toshiba Research Europe, Ltd. (United Kingdom)
P. See, Toshiba Research Europe, Ltd. (United Kingdom)
A. J. Shields, Toshiba Research Europe, Ltd. (United Kingdom)
P. Atkinson, Univ. of Cambridge (United Kingdom)
D. A. Ritchie, Univ. of Cambridge (United Kingdom)


Published in SPIE Proceedings Vol. 6902:
Quantum Dots, Particles, and Nanoclusters V
Kurt G. Eyink; Frank Szmulowicz; Diana L. Huffaker, Editor(s)

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