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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 | 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 | Семенов, А. В.; Девятов, И. А.; Рябчун, С. А.; Масленников, С. Н.; Масленникова, А. С.; Ларионов, П. А.; Воронов, Б. М.; Чулкова, Г. М. | ||||
| Title | Поглощение терагерцового электромагнитного излучения в “грязной” сверхпроводниковой пленке при произвольном виде спектральных функций | Type | Journal Article | ||
| Year | 2011 | Publication | Ж. Радиоэлектрон. | Abbreviated Journal | |
| Volume | 10 | Issue | Pages | 7 | |
| Keywords | terahertz electromagnetic radiation; superconductors; detectors of terahertz range | ||||
| Abstract | A problem of absorption of high-frequency electromagnetic field in dirty superconductor is treated within Keldysh technic. Expression for the source term in the kinetic equation for quasiparticle distribution function is derived. The result is significant for deriving a consistent microscopic theory of superconducting detectors for terahertz frequency range, perspective detectors on kinetic inductance of current-biased superconducting strip and on Josephson inductance of tunnel. В технике Келдыша рассмотрена задача о поглощении мощности высокочастотного электромагнитного поля в сверхпроводнике, удовлетворяющем условию грязного предела. Получено выражение для члена источника в кинетическом уравнении для функции распределения квазичастиц, справедливое при произвольном виде спектральных функций. Этот результат имеет значение для развития последовательной микроскопической теории сверхпроводниковых детекторов излучения терагерцового диапазона, в частности, перспективных детекторов на кинетической индуктивности смещённой током сверхпроводниковой полоски и джозефсоновской индуктивности туннельного контакта. |
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| Notes | Duplicated as 1117 | Approved | no | ||
| Call Number | RPLAB @ gujma @ | Serial | 713 | ||
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| Author | Семенов, А. В.; Девятов, И. А.; Третьяков, И. В.; Лобанов, Ю. В.; Ожегов, Р. В.; Петренко, Д. В.; Селиверстов, С. В.; Финкель, М. И. | ||||
| Title | Вывод уравнения типа уравнения гинзбурга-ландау для нанопроволоки вблизи критического магнитного поля | Type | Journal Article | ||
| Year | 2011 | Publication | Журнал радиоэлектроники | Abbreviated Journal | Ж. радиоэлектроники |
| Volume | 11 | Issue | Pages | 4 | |
| Keywords | superconductivity; nanowire; Ginzburg-Landau equation | ||||
| Abstract | Nonlinear Ginzburg-Landau equation for dirty supercondicting 1D wire is derived in the limit of high magnetic field. В пределе больших магнитных полей выведено нелинейное уравнение Гинзбурга-Ландау, описывающее состояние одномерной «грязной» нанопроволоки. |
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| Call Number | RPLAB @ gujma @ | Serial | 714 | ||
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| Author | Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Maslennikov, Sergey; Maslennikova, Anna; Kaurova, Natalia; Lobastova, Anastasia; Voronov, Boris; Gol'tsman, Gregory | ||||
| Title | Ultrawide noise bandwidth of NbN hot-electron bolometer mixers with in situ gold contacts | Type | Journal Article | ||
| Year | 2011 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | |
| Volume | 21 | Issue | 3 | Pages | 620-623 |
| Keywords | NbN HEB mixer bandwidth | ||||
| Abstract | We report a noise bandwidth of 7 GHz in the new generation of NbN hot-electron bolometer (HEB) mixers that are being developed for the space observatory Millimetron. The HEB receiver driven by a 2.5-THz local oscillator offered a noise temperature of 600 K in a 50-MHz final detection bandwidth. As the filter center frequency was swept this value remained nearly constant up to the cutoff frequency of the cryogenic amplifier at 7 GHz. We believe that such a low value of the noise temperature is due to reduced radio frequency (RF) loss at the interface between the superconducting film and the gold contacts. We have also performed gain bandwidth measurements at the superconducting transition on HEB mixers with various lengths and found them to be in excellent agreement with the results of the analytical and numerical models developed for the HEB mixer with both diffusion and phonon cooling of hot electrons. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 716 | ||
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| Author | Гольцман, Г. Н.; Разумовская, И. В.; Окунев, О. В; Чулкова, Г. М.; Корнеев, А. А.; Финкель, М. И.; Масленников, С. Н.; Семенов, А. В.; Александров, В. Н. | ||||
| Title | Сборник программ учебных дисциплин профессионального цикла подготовки магистров и бакалавров по направлению «Физика» | Type | Journal Article | ||
| Year | 2011 | Publication | Прометей | Abbreviated Journal | Прометей |
| Volume | Issue | Pages | 67 | ||
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| Notes | Учебное пособие | Approved | no | ||
| Call Number | RPLAB @ gujma @ | Serial | 717 | ||
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| Author | Lobanov, Y.; Tong, E.; Blundell, R.; Hedden, A.; Voronov, B.; Gol'tsman, G. | ||||
| Title | Large-signal frequency response of an HEB mixer: from 300 MHz to terahertz | Type | Journal Article | ||
| Year | 2011 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | |
| Volume | 21 | Issue | 3 | Pages | 628-631 |
| Keywords | waveguide NbN HEB mixers | ||||
| Abstract | We present a study of the large signal frequency response of an HEB mixer over a wide frequency range. In our experiments, we have subjected the HEB mixer to incident electromagnetic radiation from 0.3 GHz to 1 THz. The mixer element is an NbN film deposited on crystalline quartz. The mixer chip is mounted in a waveguide cavity, coupled to free space with a diagonal horn. At microwave frequencies, electromagnetic radiation is applied through the coaxial bias port of the mixer block. At higher frequencies the input signal passes via the diagonal horn feed. At each frequency, the incident power is varied and a family of I-V curves is recorded. From the curves we identify 3 distinct regimes of operation of the mixer separated by the phonon relaxation frequency and the superconducting energy gap frequency observed at about 3 GHz and 660 GHz respectively. In this paper, we will present observed curves and discuss the results of our experiment. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 719 | ||
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| Author | Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N. | ||||
| Title | Direct measurement of the gain and noise bandwidths of HEB mixers | Type | Journal Article | ||
| Year | 2011 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume | 21 | Issue | 3 | Pages | 645-648 |
| Keywords | waveguide NbN HEB mixers | ||||
| Abstract | The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 720 | ||
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| Author | Васильева, И. А.; Компанеец, В. В.; Красная, Ж. А.; Чижикова, З. А. | ||||
| Title | Проявление внутримолекулярных вибронных взаимодействий в тонкоструктурных спектрах флуоресценции и возбуждения флуоресценции полиеновых δ-диметиламинокетонов | Type | Journal Article | ||
| Year | 2011 | Publication | Оптический журнал | Abbreviated Journal | Опт. ж. |
| Volume | 78 | Issue | 5 | Pages | 3-8 |
| Keywords | спектры флуоресценции; вибрационный анализ; адиабатическое гармоническое приближение; бесфононная линия; фононное крыло | ||||
| Abstract | Проведен вибрационный анализ спектров флуоресценции и возбуждения флуоресценции, полученных методом Шпольского при 4,2 K. Рассчитаны параметры внутримолекулярных взаимодействий двух δ-диметиламинокетонов. Для определения интегральных интенсивностей вибронных полос в спектрах с тонкой структурой на интенсивном сплошном фоне выполнено моделирование спектров путем представления полосы каждого из вибронных переходов бесфононной линией и фононным крылом с определенными параметрами (полуширинами, фактором Дебая–Валлера). Показано, что нарушение зеркальной симметрии в сопряженных спектрах флуоресценции и возбуждения флуоресценции этих двух соединений может быть обÑŠяснено интерференцией франк-кондоновского и герцберг-теллеровского взаимодействий. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 721 | ||
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| Author | Antipov, Andrei; Bell, Matt; Yasar, Mesut; Mitin, Vladimir; Scharmach, William; Swihart, Mark; Verevkin, Aleksandr; Sergeev, Andrei | ||||
| Title | Luminescence of colloidal CdSe/ZnS nanoparticles: high sensitivity to solvent phase transitions | Type | Journal Article | ||
| Year | 2011 | Publication | Nanoscale Research Letters | Abbreviated Journal | Nan. Res. Lett. |
| Volume | 6 | Issue | Pages | 7 | |
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| Abstract | We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state. Several pronounced changes have been observed in the narrow temperature interval near the water melting point. First of all, the luminescence intensity substantially (approximately 50%) increases near the transition. In a large temperature scale, the energy peak of the photoluminescence decreases with temperature due to temperature dependence of the energy gap. Near the melting point, the peak shows N-type dependence with the maximal changes of approximately 30 meV. The line width increases with temperature and also shows N-type dependence near the melting point. The observed effects are associated with the reconstruction of ligands near the ice/water phase transition. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 722 | ||
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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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