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Author Mitin, Vladimir; Antipov, Andrei; Sergeev, Andrei; Vagidov, Nizami; Eason, David; Strasser, Gottfried
Title Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers Type Journal Article
Year 2011 Publication Nanoscale Research Letters Abbreviated Journal Nanoscale res lett
Volume 6 Issue 1 Pages 6
Keywords (down) Quantum dots; Infrared detectors; Photoresponse; Doping; Potential barriers; Capture processes
Abstract Potential barriers around quantum dots (QDs) play a key role in kinetics of photoelectrons. These barriers are always created, when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics, we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases ~30 times as the height of potential barriers changes from 30 to 130 meV.
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Call Number RPLAB @ gujma @ Serial 712
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Author Wiechers, C.; Lydersen, L.; Wittmann, C.; Elser, D.; Skaar, J.; Marquardt, Ch; Makarov, V.; Leuchs, G.
Title After-gate attack on a quantum cryptosystem Type Journal Article
Year 2011 Publication New J. Phys. Abbreviated Journal
Volume 13 Issue 1 Pages 14
Keywords (down) quantum cryptography; hacking; interception; attack; SPD; APD; QKD
Abstract We present a method to control the detection events in quantum key distribution systems that use gated single-photon detectors. We employ bright pulses as faked states, timed to arrive at the avalanche photodiodes outside the activation time. The attack can remain unnoticed, since the faked states do not increase the error rate per se. This allows for an intercept-resend attack, where an eavesdropper transfers her detection events to the legitimate receiver without causing any errors. As a side effect, afterpulses, originating from accumulated charge carriers in the detectors, increase the error rate. We have experimentally tested detectors of the system id3110 (Clavis2) from ID Quantique. We identify the parameter regime in which the attack is feasible despite the side effect. Furthermore, we outline how simple modifications in the implementation can make the device immune to this attack.
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Call Number RPLAB @ gujma @ Serial 730
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Author Курочкин, Юрий Владимирович
Title Методы повышения пропускной способности квантовой криптографии Type Manuscript
Year 2011 Publication МФТИ Abbreviated Journal
Volume Issue Pages
Keywords (down) quantum cryptography
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Call Number Serial 762
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Author Kumar, Sushil; Chan, Chun Wang I.; Hu, Qing; Reno, John L.
Title A 1.8-THz quantum cascade laser operating significantly above the temperature of hw/k Type Journal Article
Year 2011 Publication Nature Physics Abbreviated Journal
Volume 7 Issue Pages 166-171
Keywords (down) QCL, 2 mW at 155 K and 1.8 THz
Abstract Several competing technologies continue to advance the field of terahertz science; of particular importance has been the development of a terahertz semiconductor quantum cascade laser (QCL), which is arguably the only solid-state terahertz source with average optical power levels of much greater than a milliwatt. Terahertz QCLs are required to be cryogenically cooled and improvement of their temperature performance is the single most important research goal in the field. Thus far, their maximum operating temperature has been empirically limited to ~planckω/kB, a largely inexplicable trend that has bred speculation that a room-temperature terahertz QCL may not be possible in materials used at present. Here, we argue that this behaviour is an indirect consequence of the resonant-tunnelling injection mechanism employed in all previously reported terahertz QCLs. We demonstrate a new scattering-assisted injection scheme to surpass this limit for a 1.8-THz QCL that operates up to ~1.9planckω/kB (163 K). Peak optical power in excess of 2 mW was detected from the laser at 155 K. This development should make QCL technology attractive for applications below 2 THz, and initiate new design strategies for realizing a room-temperature terahertz semiconductor laser.
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Call Number Serial 631
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Author Чулкова, Г. М.; Семёнов, А. В.; Дивочий, А. В.; Тархов, М. А.
Title Сверхпроводниковый однофотонный детектор с разрешением числа фотонов для систем дальней телекоммуникационной связи Type Journal Article
Year 2011 Publication Ж. радиоэлектрон. Abbreviated Journal Ж. радиоэлектрон.
Volume Issue 12 Pages 1-6
Keywords (down) PNR SSPD, SNSPD
Abstract Рассмотрена возможность применения сверхпроводникового однофотонного детектора, разрешающего число фотонов, в качестве датчика приёмных модулей телекоммуникационных линий. Показано, что для достижения доли ошибочных битов на уровне 10-11 достаточно на два порядка меньшей мощности в оптическом импульсе, чем при использовании существующих приёмных модулей.
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Call Number RPLAB @ sasha @ чулковасверхпроводниковый Serial 1031
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