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May, 2004 EEEL Demonstrates Photon Antibunching at High Temperature from Single Quantum Dot |
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Rich Mirin of the EEEL Optoelectronics Division has demonstrated photon antibunching from a single, self-assembled InGaAs quantum dot at temperatures from 5 K up to 135 K, and single photon emission up to 120 K. Emitters of single photons on demand are important for low light level metrology and quantum key distribution, or quantum cryptography. For practical implementation, photon sources should operate at high temperatures. Colloidal CdSe quantum dots, nitrogen vacancy centers, and single molecules have demonstrated room-temperature single photon emission; however the first two systems exhibit blinking, and some single molecules exhibit photobleaching, both of which degrade performance. Epitaxial InGaAs/GaAs quantum dots are attractive as single photon emitters due to their ease of fabrication and inclusion with monolithic microcavities, short spontaneous emission lifetimes, and the possibility of electrical injection. Mirin grew InGaAs quantum dots using molecular beam epitaxy and isolated single dots with etched mesas. The second-order intensity correlation, which is a measure of the independence of single photon emitters, was derived by measuring the coincidence photon counts in a Hanbury Brown-Twiss interferometer. Contributions to the emission other than that from the uncharged single exciton were separated by analysis of the photoluminescence spectra. Single electron-hole pair injection by electrical means should improve the performance of an InGaAs quantum dot single photon source by removing the possibility of charged exciton or biexciton formation. The results
represent the highest reported temperature for non-classical light emission
from the InGaAs/GaAs system (see Appl. Phys. Lett. 84, 1260 (2004)). The
single photon source is being developed for applications including high-accuracy
radiometry in which optical power and energy measurements are calibrated
by counting photons, ultra-secure communication, and quantum optics studies.
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