Luminescence of a Cooper Pair

This paper theoretically discusses the photon emission spectra of a superconducting pn-junction. On the basis of the second order perturbation theory for electron-photon interaction, we show that the recombination of a Cooper with two p-type carriers causes drastic enhancement of the luminescence intensity. The calculated results of photon emission spectra explain characteristic features of observed signal in an recent experiment. Our results indicate high functionalities of superconducting light-emitting devices.Comment: 4 pages, 3 figures embedde

胆嚢前癌性病変および胆嚢癌組織における腸上皮化生の検討

胆嚢粘膜の腸上皮化生が胆嚢癌の組織発生にどのように関与しているかを探る目的で,胆嚢前癌性病変および胆嚢癌組織内にみられた化生性変化の種類と頻度を組織学的に検討した.対象として腺腫8例,異型上皮7例,過形成性ポリープ20例,粘膜癌11例および進行癌37例の計83例を用いた.その結果,異型上皮では杯細胞,粘液腺および内分泌細胞が60～80%の頻度でみられ,また過形成性ポリープでも粘液腺,杯細胞,内分泌細胞およびパネート細胞がおのおの10～100%の頻度で認められた.しかし腺腫では杯細胞のみが25%にみられたにすぎなかった.また粘膜癌では杯細胞と内分泌細胞が22～36%で,進行癌では同様の細胞が8～16%で認められた.以上より,胆嚢粘膜の腸上皮化生は,種々の化生性変化を高率に伴う異型上皮や過形成性ポリープから癌化する場合に重要な役割を演じ,化生性変化を伴うことが少ない腺腫からの癌化にはあまり関与しないものと推定した.In order to study the relationship between mucosal metaplastic changes and cancer histogenesis in the gallbladder, precancerous lesions and carcinomas were investigated histologically for frequency and the variety of intestinal metaplasia in them. The materials included 8 cases of adenoma, 7 cases of dysplasia, 20 cases of hyperplastic polyp, 11 cases of mucosal carcinoma and 37 cases of advanced carcinoma. Goblet cells, mucous glands and endocrine cells were detected in 60-80% of cases with dysplasia and 10-100% of cases with hyperplastic polyp. However, adenoma only displayed goblet cells in 25% of cases. In cases with carcinoma, goblet cells and endocrine cells were present in 22-36% of mucosal carcinomas and 8-16% of advanced carcinomas, all of which were well differentiated adenocarcinomas. These results seem to indicate that intestinal metaplasia play an important role in malignant changes from dysplasia and hyperplastic polyp rather than adenoma

Improved luminescence efficiency of InAs quantum dots grown on atomic terraced GaAs surface prepared with in-situ chemical etching

Observation of the enhanced luminescence efficiency of InAs quantum dots (QDs) grown on atomically controlled GaAs surfaces is reported. With the trisdimethylaminoarsenic (TDMAAs) in-situ surface etching process, formation of atomic steps and terraces on GaAs surfaces were clearly observed. InAs QDs grown on the processed GaAs surfaces showed the clear dependence of QDs size, density and optical characteristics on the surface properties, i.e., the increase of the QDs height and diameter the decrease of the QDs density. About 6-times enhancement of photoluminescence efficiency which has the peak around 1550-nm wavelength was observed by growing InAs QDs on atomically controlled GaAs surfaces. This is due to the migration enhancement of InAs during thegrowth the QDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Observation of enhanced luminescence emitted from InAs quantum dots with direct contact to superconducting niobium stripe

Observation of drastically enhanced luminescence emitted from InAs quantum dots (QDs) which were in direct contact to superconducting Niobium (Nb) is reported. Although the PL intensity was essentially temperature independent without Nb stripe, drastic temperature dependence was observed with the presence of the Nb stripe. PL intensity was substantially increased below the Nb superconducting critical temperature (Tc). About 3-times enhancement was observed below Tc. This phenomenon is attributed to the Cooper pairs penetrated from the superconducting Nb stripe to adjacent InAs QDs by the proximity effect. This is the first experimental demonstration that the Cooper pairs enhance radiative recombination through QDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Enhanced Photon Extraction from a Quantum Dot Induced by a Silver Microcolumnar Photon Reflector

We have fabricated silver microcolumnar photon reflectors to enhance the photon extraction efficiency from a quantum dot. The mechanically robust planar structure is favorable to couple to optical fibers for stable and efficient single-photon sources. A high photon extraction efficiency of up to 18% is achieved. Furthermore, strong suppression of multiphoton generation is confirmed. The proposed structure is quite promising toward the implementation of practical quantum key distribution systems with dot-fiber-coupled photon sources