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Author Gustafsson, Martin V.; Santos, Paulo V.; Johansson, Göran; Delsing, Per
Title Local probing of propagating acoustic waves in a gigahertz echo chamber Type Journal Article
Year 2012 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 8 Issue 4 Pages 338-343
Keywords (down) fromIPMRAS
Abstract In the same way that micro-mechanical resonators resemble guitar strings and drums, surface acoustic waves resemble the sound these instruments produce, but moving over a solid surface rather than through air. In contrast with oscillations in suspended resonators, such propagating mechanical waves have not before been studied near the quantum mechanical limits. Here, we demonstrate local probing of surface acoustic waves with a displacement sensitivity of 30amRMSHz-1/2 and detection sensitivity on the single-phonon level after averaging, at a frequency of 932MHz. Our probe is a piezoelectrically coupled single-electron transistor, which is sufficiently fast, non-destructive and localized to enable us to track pulses echoing back and forth in a long acoustic cavity, self-interfering and ringing the cavity up and down. We project that strong coupling to quantum circuits will enable new experiments, and hybrids using the unique features of surface acoustic waves. Prospects include quantum investigations of phonon-phonon interactions, and acoustic coupling to superconducting qubits for which we present favourable estimates.
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Call Number RPLAB @ gujma @ Serial 813
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Author Korotkov, Alexander N.
Title Entanglement preservation: The Sleeping Beauty approach Type Journal Article
Year 2012 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 8 Issue 2 Pages 107-108
Keywords (down) fromIPMRAS
Abstract Two-qubit entanglement can be preserved by partially measuring the qubits to leave them in a 'lethargic' state. The original state is restored using quantum measurement reversal after the qubits have travelled through a decoherence channel.
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Call Number RPLAB @ gujma @ Serial 814
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Author Kim, Yong-Su; Lee, Jong-Chan; Kwon, Osung; Kim, Yoon-Ho
Title Protecting entanglement from decoherence using weak measurement and quantum measurement reversal Type Journal Article
Year 2012 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 8 Issue 2 Pages 117-120
Keywords (down) fromIPMRAS
Abstract Decoherence, often caused by unavoidable coupling with the environment, leads to degradation of quantum coherence. For a multipartite quantum system, decoherence leads to degradation of entanglement and, in certain cases, entanglement sudden death. Tackling decoherence, thus, is a critical issue faced in quantum information, as entanglement is a vital resource for many quantum information applications including quantum computing, quantum cryptography, quantum teleportation and quantum metrology. Here, we propose and demonstrate a scheme to protect entanglement from decoherence. Our entanglement protection scheme makes use of the quantum measurement itself for actively battling against decoherence and it can effectively circumvent even entanglement sudden death.
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Call Number RPLAB @ gujma @ Serial 815
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Author Bason, Mark G.; Viteau, Matthieu; Malossi, Nicola; Huillery, Paul; Arimondo, Ennio; Ciampini, Donatella; Fazio, Rosario; Giovannetti, Vittorio; Mannella, Riccardo; Morsch, Oliver
Title High-fidelity quantum driving Type Journal Article
Year 2012 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 8 Issue 2 Pages 147-152
Keywords (down) fromIPMRAS
Abstract Accurately controlling a quantum system is a fundamental requirement in quantum information processing and the coherent manipulation of molecular systems. The ultimate goal in quantum control is to prepare a desired state with the highest fidelity allowed by the available resources and the experimental constraints. Here we experimentally implement two optimal high-fidelity control protocols using a two-level quantum system comprising Bose-Einstein condensates in optical lattices. The first is a short-cut protocol that reaches the maximum quantum-transformation speed compatible with the Heisenberg uncertainty principle. In the opposite limit, we realize the recently proposed transitionless superadiabatic protocols in which the system follows the instantaneous adiabatic ground state nearly perfectly. We demonstrate that superadiabatic protocols are extremely robust against control parameter variations, making them useful for practical applications.
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Call Number RPLAB @ gujma @ Serial 816
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Author Semenov, A. V.; Devyatov, I. A.; Korneev, A. A.; Smirnov, K. V.; Goltsman, G. N.; Melnikov, A. P.
Title Derivation of expression for thermodynamic potential of “dirty” superconductor Type Journal Article
Year 2012 Publication Rus. J. Radio Electron. Abbreviated Journal Rus. J. Radio Electron.
Volume Issue 4 Pages
Keywords (down) dirty superconductor, Usadel theory, thermodynamic potential
Abstract We derive a formula for thermodynamic potential of dirty superconductor which express it via isotropic quasiclassical Green functions of Usadel theory. Our result allows unify description of dynamic processes and fluctuations in superconducting nano-electronic devices.
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Language Russian Summary Language Original Title
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Notes 7 pages Approved no
Call Number Serial 1824
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Author Семенов, А. В.; Корнеев, А. А.; Смирнов, А. В.; Смирнов, К. В.; Ожегов, Р. В.; Окунев, О. В.; Гольцман, Г. Н.; Девятов, И. А.
Title Линейные по мощности поглощаемого излучения поправки к спектральным функциям «грязного» сверхпроводника и отклик сверхпроводниковых детекторов Type Journal Article
Year 2012 Publication Преподаватель ХХI век Abbreviated Journal
Volume Issue 3 Pages 216-220
Keywords (down) dirty superconductor film
Abstract В статье развит метод расчета малых поправок к спектральным функциям пленки «грязного» сверхпроводника, возникающих под действием поглощаемой мощности электромагнитного излучения. Метод пригоден в случае спектральных функций произвольного вида, что позволяет применять его для расчета отклика сверхпроводниковых детекторов излучения различного типа.
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Language Russian Summary Language Original Title
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Notes Approved no
Call Number Serial 1822
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Author D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel
Title Detection efficiency of a spiral-nanowire superconducting single-photon detector Type Journal Article
Year 2012 Publication Abbreviated Journal
Volume Issue Pages
Keywords (down) Critical current, Nanoscale devices, Superconducting photodetectors.
Abstract We investigate the detection efficiency of a spiral layout of a Superconducting Nanowire Single-Photon Detector (SNSPD). The design is less susceptible to the critical current reduction in sharp turns of the nanowire than the conventional meander design. Detector samples with different nanowire width from 300 to 100 nm are patterned from a 4 nm thick NbN film deposited on sapphire substrates. The critical current IC at 4.2 K for spiral, meander, and simple bridge structures is measured and compared. On the 100 nm wide samples, the detection efficiency is measured in the wavelength range 400-1700 nm and the cut-off wavelength of the hot-spot plateau is determined. In the optical range, the spiral detector reaches a detection efficiency of 27.6%, which is ~1.5 times the value of the meander. In the infrared range the detection efficiency is more than doubled.
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Corporate Author D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel Thesis
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Notes Approved no
Call Number RPLAB @ seleznev @ Serial 880
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Author Vercruyssen, N.; Verhagen, T. G. A.; Flokstra, M. G.; Pekola, J. P.; Klapwijk, T. M.
Title Evanescent states and nonequilibrium in driven superconducting nanowires Type Journal Article
Year 2012 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 85 Issue Pages 224503(1-10)
Keywords (down) Al HEB, Al superconducting nanowire, global state, bimodal state, quasiclassical kinetic equations, Usadel equation
Abstract We study the nonlinear response of current transport in a superconducting diffusive nanowire between normal reservoirs. We demonstrate theoretically and experimentally the existence of two different superconducting states appearing when the wire is driven out of equilibrium by an applied bias, called the global and bimodal superconducting states. The different states are identified by using two-probe measurements of the wire, and measurements of the local density of states with tunneling probes. The analysis is performed within the framework of the quasiclassical kinetic equations for diffusive superconductors.
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Notes Approved no
Call Number Serial 898
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Author Чулкова, Г. М.; Корнеев, А. А.; Смирнов, К. В.; Окунев, О. В.
Title Энергетическая релаксация в примесных металлах, двумерном электронном газе в AlGaAs-GaAs, сверхпроводниковых пленках NbN и детекторы субмиллиметрового и ик излучения на их основе Type Book Whole
Year 2012 Publication Abbreviated Journal
Volume Issue Pages
Keywords (down) 2DEG, AlGaAs/GaAs, NbN detectors
Abstract Монография посвящена обзору исследований влияния эффектов электронного беспорядка на электронное взаимодействие в металлах, сверхпроводниках, полупроводниках, а также в различных низкоразмерных структурах. Актуальность поднятых в монографии вопросов определяется интенсивным развитием нанотехнологий, созданием новых наноструктурированных материалов и уникальных наноэлементов для электроники и фотоники. Упругое электронное рассеяние на границах наноструктур качественно меняет взаимодействие электронов с фонолами, что, безусловно, должно учитываться при проектировании соответствующей элементной базы. Прикладная часть работы посвящена контролируемой модификации электронных процессов для оптимизации новых наносенсоров на основе электронного разогрева в сверхпроводниковых и полупроводниковых структурах. Монография предназначена для студентов старших курсов, аспирантов и начинающих следователей, работающих в области сверхпроводниковой наноэлектроники.
Address Москва
Corporate Author Thesis
Publisher Прометей, МПГУ Place of Publication Editor
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ISSN ISBN 978-5-4263-0118-4 Medium
Area Expedition Conference
Notes УДК: 537.311 Approved no
Call Number Serial 1818
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Author Swetz, D. S.; Bennett, D. A.; Irwin, K. D.; Schmidt, D. R.; Ullom, J. N.
Title Current distribution and transition width in superconducting transition-edge sensors Type Journal Article
Year 2012 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 101 Issue Pages 242603
Keywords (down)
Abstract Present models of the superconducting-to-normal transition in transition-edge sensors (TESs) do not describe the current distribution within a biased TES. This distribution is complicated by normal-metal features that are integral to TES design. We present a model with one free parameter that describes the evolution of the current distribution with bias. To probe the current distribution experimentally, we fabricated TES devices with different current return geometries. Devices where the current return geometry mirrors current flow within the device have sharper transitions, thus allowing for a direct test of the current-flow model.Measurements from these devices show that current meanders through a TES low in the resistivetransition but flows across the normal-metal features by 40% of the normal-state resistance. Comparison of transition sharpness between device designs reveals that self-induced magnetic fields play an important role in determining the width of the superconducting transition.
Address TES, current distribution
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Notes Recommended by Klapwijk Approved no
Call Number Serial 930
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