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Author Ожегов, Р.В.; Окунев, О.В.; Гольцман, Г.Н.
Title Флуктуационная чувствительность сверхпроводящего болометрического смесителя на эффекте разогрева электронного газа Type Journal Article
Year 2009 Publication Радиотехника Abbreviated Journal
Volume Issue 3 Pages 120-124
Keywords смеситель на горячих электронах; флуктуационная чувствительность; тепловизор терагерцевого диапазона частот; hot-electron bolometer mixer; Imaging system; Noise equivalent temperature difference; Heterodyne receiver; Terahertz range
Abstract Interest in research in the terahertz range is driven by a great number of various applications, where terahertz instruments may play a leading role. To name just a few, such applications include study of the cosmic microwave background radiation and the distribution of the dark matter, medicine, navigation, fire alarm, security systems and environmental monitoring. The paper discusses the possibility of using a receiver based on the hot-electron effect in superconducting films as an imaging system. We present the results of the noise equivalent temperature difference (NETD) measurements performed with a hot-electron bolometer mixer made from a thin superconducting film. The receiver with a noise temperature of ~ 3800 K at a local oscillator frequency of 300 GHz a bandwidth of 500 MHz and an integration time of 1 s has offered an NETD of 0.5 K. We have also developed a technique that enabled us to reduce the contribution of the mixer gain fluctuations to the overall system instability. As of this writing, the above value of the NETD is the lowest value offered for this type of receiver, which indicates the possibility to use such receivers in real-time imaging systems. The technique offered in the paper for achieving the limiting value of the NETD offers an alternative to the phase-locking scheme.

Представены результаты измерения флуктуационной чувствительности (NETD – noise equivalent temperature difference) болометрического смесителя на эффекте разогрева электронного газа в тонких сверхпроводящих пленках. Получено предельное значение NETD, равное 0,5 К, при шумовой температуре приемника 3800 К, ширине полосы преобразования 500 МГц, постоянной времени 1 с и частоте гетеродина 300 ГГц. Разработана методика достижения предельной флуктуационной чувствительности, позволяющая избежать влияния нестабильности коэффициента преобразования смесителя.
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Call Number RPLAB @ gujma @ Serial 728
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Author Lydersen, Lars; Wiechers, Carlos; Wittmann, Christoffer; Elser, Dominique; Skaar, Johannes; Makarov, Vadim
Title Thermal blinding of gated detectors in quantum cryptography Type Journal Article
Year 2010 Publication Optics Express Abbreviated Journal Opt. Express
Volume 18 Issue 26 Pages 27938-27954
Keywords quantum cryptography; QKD; hacking; SPD; APD
Abstract It has previously been shown that the gated detectors of two commercially available quantum key distribution (QKD) systems are blindable and controllable by an eavesdropper using continuous-wave illumination and short bright trigger pulses, manipulating voltages in the circuit [L. Lydersen et al., Nat. Photonics DOI:10.1038/nphoton.2010.214]. This allows for an attack eavesdropping the full raw and secret key without increasing the quantum bit error rate (QBER). Here we show how thermal effects in detectors under bright illumination can lead to the same outcome. We demonstrate that the detectors in a commercial QKD system Clavis2 can be blinded by heating the avalanche photo diodes (APDs) using bright illumination, so-called thermal blinding. Further, the detectors can be triggered using short bright pulses once they are blind. For systems with pauses between packet transmission such as the plug-and-play systems, thermal inertia enables Eve to apply the bright blinding illumination before eavesdropping, making her more difficult to catch.
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Call Number RPLAB @ gujma @ Serial 729
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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 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 Ожегов, Роман Викторович
Title Флуктуационная чувствительность и стабильность приемников с СИС и HEB смесителями для терагерцового тепловидения Type Journal Article
Year 2011 Publication Радиофизика Abbreviated Journal
Volume Issue Pages 135
Keywords HEB
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Call Number RPLAB @ gujma @ Serial 731
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Author Килин, С. Я.
Title Квантовая информация Type Journal Article
Year 1999 Publication Успехи физических наук Abbreviated Journal УФН
Volume 169 Issue 5 Pages 507-527
Keywords quantum cryptography; QKD, BB84
Abstract Новое направление физики – квантовая информация – возникло на стыке квантовой механики, оптики, теории относительности и программирования, дискретной математики, лазерной физики и спектроскопии и включает в себя вопросы квантовых вычислений, квантовых компьютеров, квантовой телепортации и квантовой криптографии, проблемы декогеренции и спектроскопии одиночных молекул и примесных центров. Сообщается о некоторых новых результатах в этой быстро развивающейся области исследований.
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Call Number RPLAB @ gujma @ Serial 732
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