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Pfeiffer J, Schuster M, Abdumalikov AA, Ustinov AV. Observation of soliton fusion in a Josephson array. PHYSICAL REVIEW LETTERS 2006; 96:034103. [PMID: 16486706 DOI: 10.1103/physrevlett.96.034103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2005] [Indexed: 05/06/2023]
Abstract
The behavior of topological solitons in a parallel array of a Josephson junction is studied experimentally. We observe the fusion of two relativistic solitons of the same polarity into a single soliton. The soliton carries two quanta of magnetic flux and, most strikingly, travels 18% faster than an ordinary soliton under the same driving force. We also find a variety of bunched states composed of solitons of the same polarity, moving with fixed separation.
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Andronova VL, Pchelintseva AA, Ustinov AV, Petrunina AL, Korshun VA, Skorobogatyĭ MV, Galegov GA. [Antiherpetic activity of 5-alkynyl derivatives of 2'-deoxyuridine]. Vopr Virusol 2006; 51:34-8. [PMID: 16515041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A series of new 5-alkynyl-2'-deoxyuridines have been synthesized and their antiherpetic activity was tested in the cultured Vero cells on a model of herpes simplex virus type 1, including its acyclovir-resistant strains. Some test compounds were found to have a significant specific antiherpetic activity. Nucleoside XIV showed the greatest activity. Compounds IV and X also has displayed a significant activity against the herpes simplex virus type 1 strain that is highly resistant to acyclovir. Examining the combined action of substance II with acyclovir and ganciclovir has revealed a synergetic effect.
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Giller DB, Tokaev KV, Bagirov MA, Sadovnikova SS, Bondarev GB, Ustinov AV, Martel' II, Giller BM, Giller GV. [Outcomes of video-assisted thoracic lung resections and pneumonectomies in patients with pulmonary tuberculosis]. PROBLEMY TUBERKULEZA I BOLEZNEI LEGKIKH 2006:38-42. [PMID: 17002057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The paper pools some experience with 6 videothoracoscopic and 505 video-assisted thoracoscopic (VATS) resections of the lung and 105 VATS pneumonectomies. The bulk of the operations [451 (73.2%)] was made for pulmonary tuberculosis in patients aged 7 to 77 years. 81% operations by separately treating root elements, including all pneumonectomies and major lung resections, were performed. A new SOMI-80 suturing apparatus designed for mini-invasive surgery was employed to suture lung tissue in most cases. Intraoperative and postoperative complications occurred in 5 and 8 cases, respectively. The efficiency of operations for tuberculosis was 98.6%.
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Ustinov AV, Giller DB, Nabokova TS, Lenev IN. [A case of acute respiratory distress syndrome in a female patient with a single lung]. PROBLEMY TUBERKULEZA I BOLEZNEI LEGKIKH 2006:70-2. [PMID: 17139838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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Pchelintseva AA, Skorobogatyj MV, Petrunina AL, Andronova VL, Galegov GA, Astakhova IV, Ustinov AV, Malakhov AD, Korshun VA. Synthesis and evaluation of anti-HSV activity of new 5-alkynyl-2'-deoxyuridines. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2005; 24:923-6. [PMID: 16248063 DOI: 10.1081/ncn-200059280] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Eight 5-alkynyl-2'deoxyuridines containing different bulky substituents have been prepared and tested against HSV-1 in Vero cells. The compounds show positive antiviral activity. There is no obvious correlation between activity and substituent size. The nature of the linker between uracil and a substituent appears to be more important for antiviral properties: nucleosides containing arylethynyl groups show higher activity.
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Ustinov AV, Coqui C, Kemp A, Zolotaryuk Y, Salerno M. Ratchetlike dynamics of fluxons in annular Josephson junctions driven by biharmonic microwave fields. PHYSICAL REVIEW LETTERS 2004; 93:087001. [PMID: 15447215 DOI: 10.1103/physrevlett.93.087001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Indexed: 05/24/2023]
Abstract
Experimental observation of the unidirectional motion of a topological soliton driven by a biharmonic ac force of zero mean is reported. The observation is made by measuring the current-voltage characteristics for a fluxon trapped in an annular Josephson junction that was placed into a microwave field. The dependence of the fluxon mean velocity at zero dc bias versus the phase shift between the first and second harmonic of the driving force is in qualitative agreement with theoretical expectations.
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Koval Y, Fistul MV, Ustinov AV. Enhancement of Josephson phase diffusion by microwaves. PHYSICAL REVIEW LETTERS 2004; 93:087004. [PMID: 15447218 DOI: 10.1103/physrevlett.93.087004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Indexed: 05/24/2023]
Abstract
We report an experimental and theoretical study of the phase diffusion in small Josephson junctions under microwave irradiation. A peculiar enhancement of the phase diffusion by microwaves is observed. The enhancement manifests itself by a pronounced current peak in the current-voltage characteristics. The voltage position V(top) of the peak increases with the power P of microwave radiation as V(top) proportional to sqrt[P], while its current amplitude weakly decreases with P. As the microwave frequency increases, the peak feature evolves into Shapiro steps with a finite slope. Our theoretical analysis, taking into account the enhancement of incoherent superconducting current by multiphoton absorption, is in good agreement with experimental data.
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Sivakov AG, Glukhov AM, Omelyanchouk AN, Koval Y, Müller P, Ustinov AV. Josephson behavior of phase-slip lines in wide superconducting strips. PHYSICAL REVIEW LETTERS 2003; 91:267001. [PMID: 14754079 DOI: 10.1103/physrevlett.91.267001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Indexed: 05/24/2023]
Abstract
Phase-slip lines can be viewed as dynamically created Josephson junctions in a homogeneous superconducting film. In contrast to phase-slip centers, phase-slip lines occur in wide superconducting strips, where the order parameter may vary in two dimensions. We investigated phase-slip lines in two different materials using several methods. We observed Shapiro steps under microwave radiation, which shows that the frequency of the order parameter oscillation is equal to Josephson frequency. A periodic oscillation of a critical current versus the applied magnetic field was found in strips with a hole in the middle. The latter effect provides a clear evidence of macroscopic quantum interference across a phase-slip line. We have used low temperature scanning laser microscopy to visualize the phase-slip lines and to distinguish them from possible local inhomogeneities in the films.
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Fistul MV, Wallraff A, Koval Y, Lukashenko A, Malomed BA, Ustinov AV. Quantum dissociation of a vortex-antivortex pair in a long josephson junction. PHYSICAL REVIEW LETTERS 2003; 91:257004. [PMID: 14754141 DOI: 10.1103/physrevlett.91.257004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Indexed: 05/24/2023]
Abstract
The thermal and the quantum dissociation of a single vortex-antivortex (VAV) pair in an annular Josephson junction is experimentally observed and theoretically analyzed. In our experiments, the VAV pair is confined in a pinning potential controlled by external magnetic field and bias current. The dissociation of the pinned VAV pair manifests itself in a switching of the Josephson junction from the superconducting to the resistive state. The observed temperature and field dependence of the switching current distribution is in agreement with the analysis. The crossover from the thermal to the macroscopic quantum tunneling mechanism of dissociation occurs at a temperature of about 100 mK. We also predict the specific magnetic field dependence of the oscillatory energy levels of the pinned VAV state.
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Wallraff A, Lukashenko A, Lisenfeld J, Kemp A, Fistul MV, Koval Y, Ustinov AV. Quantum dynamics of a single vortex. Nature 2003; 425:155-8. [PMID: 12968173 DOI: 10.1038/nature01826] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2003] [Accepted: 06/17/2003] [Indexed: 11/08/2022]
Abstract
Vortices occur naturally in a wide range of gases and fluids, from macroscopic to microscopic scales. In Bose-Einstein condensates of dilute atomic gases, superfluid helium and superconductors, the existence of vortices is a consequence of the quantum nature of the system. Quantized vortices of supercurrent are generated by magnetic flux penetrating the material, and play a key role in determining the material properties and the performance of superconductor-based devices. At high temperatures the dynamics of such vortices are essentially classical, while at low temperatures previous experiments have suggested collective quantum dynamics. However, the question of whether vortex tunnelling occurs at low temperatures has been addressed only for large collections of vortices. Here we study the quantum dynamics of an individual vortex in a superconducting Josephson junction. By measuring the statistics of the vortex escape from a controllable pinning potential, we demonstrate the existence of quantized levels of the vortex energy within the trapping potential well and quantum tunnelling of the vortex through the pinning barrier.
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Abstract
In this paper I review our experiments on visualization of discrete breathers (intrinsic localized modes) in nonlinear lattices made of Josephson junctions. Properties of Josephson junctions and arrays made of such junctions are discussed in the Introduction. The visualization technique based on low temperature laser scanning microscopy (LSM) is described in detail. Images of discrete breathers in Josephson junction arrays of various geometries are presented. Possible further experiments that can be done using LSM technique are envisioned.
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Pignatelli F, Ustinov AV. Observation of breatherlike states in a single Josephson cell. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:036607. [PMID: 12689179 DOI: 10.1103/physreve.67.036607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2002] [Indexed: 05/24/2023]
Abstract
We present experimental observation of broken-symmetry states in a superconducting loop with three Josephson junctions. These states are generic for discrete breathers in Josephson ladders. The existence region of the breatherlike states is found to be in good accordance with the theoretical expectations. We observed three different resonant states in the current-voltage characteristics of the broken-symmetry state, as predicted by theory. The experimental dependence of the resonances on the external magnetic field is studied in detail.
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Wallraff A, Duty T, Lukashenko A, Ustinov AV. Multiphoton transitions between energy levels in a current-biased Josephson tunnel junction. PHYSICAL REVIEW LETTERS 2003; 90:037003. [PMID: 12570519 DOI: 10.1103/physrevlett.90.037003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2002] [Indexed: 05/24/2023]
Abstract
The escape of a current-biased Josephson tunnel junction from the zero-voltage state in the presence of weak microwave radiation is investigated experimentally at low temperatures. The measurements of the junction switching current distribution indicate the macroscopic quantum tunneling of the phase below a crossover temperature of T small star, filled approximately 280 mK. At temperatures below T small star, filled we observe both single-photon and multiphoton transitions between the junction energy levels by applying microwave radiation in the frequency range between 10 and 38 GHz to the junction. These observations reflect the anharmonicity of the junction potential containing only a small number of levels.
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Binder P, Ustinov AV. Exploration of a rich variety of breather modes in Josephson ladders. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 66:016603. [PMID: 12241496 DOI: 10.1103/physreve.66.016603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2002] [Indexed: 05/23/2023]
Abstract
We report on systematic measurements of localized rotational modes in Josephson junction arrays. These modes, also known as rotobreathers, persist under the action of uniform bias force. In contrast to previous experiments, here we focus on systems with strong coupling between rotators. In ladders with either open or periodic boundary conditions, we observe a very rich variety of stable dynamic states including symmetric, asymmetric, combined, hybrid, coupled, and truncated modes. The switching scenarios between different states are discussed in detail.
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Schuster M, Binder P, Ustinov AV. Observation of breather resonances in Josephson ladders. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:016606. [PMID: 11800810 DOI: 10.1103/physreve.65.016606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2001] [Indexed: 05/23/2023]
Abstract
We report experimental observation of resonances excited by nonlinear localized states (rotobreathers) in Josephson junction ladders. The rotobreathers are found to persist in a frequency range that allows for their resonant interaction with linear electromagnetic modes in the ladders. This interaction leads to nearly constant voltage steps on the current-voltage characteristics. We also present numerical simulations that agree well with experimental data and confirm the resonant interaction between breathers and linear waves. Resonances occur at the base frequency as well as higher harmonics of the linear modes. The observed substructures on the resonances are attributed to the cavity modes for the ladders. Both experimental and simulated current-voltage characteristics show good quantitative agreement with an analytically calculated dispersion relation for linear electromagnetic modes.
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Binder P, Abraimov D, Ustinov AV. Diversity of discrete breathers observed in a josephson ladder. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 62:2858-2862. [PMID: 11088768 DOI: 10.1103/physreve.62.2858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2000] [Indexed: 05/23/2023]
Abstract
We generate and observe discrete rotobreathers in Josephson junction ladders with open boundaries. Rotobreathers are localized excitations that persist under the action of a spatially uniform force. We find a rich variety of stable dynamic states including pure symmetric, pure asymmetric, and mixed states. The parameter range where the discrete breathers are observed in our experiment is limited by retrapping due to dissipation.
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Binder P, Abraimov D, Ustinov AV, Flach S, Zolotaryuk Y. Observation of breathers in Josephson ladders. PHYSICAL REVIEW LETTERS 2000; 84:745-748. [PMID: 11017362 DOI: 10.1103/physrevlett.84.745] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/1999] [Indexed: 05/23/2023]
Abstract
We report on the observation of spatially localized excitations in a ladder of small Josephson junctions. The excitations are whirling states which persist under a spatially homogeneous force due to the bias current. These states of the ladder are visualized using a low temperature scanning laser microscopy. We also compute breather solutions with high accuracy in corresponding model equations. The stability analysis of these solutions is used to interpret the measured patterns in the I-V characteristics.
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Wallraff A, Ustinov AV, Kurin VV, Shereshevsky IA, Vdovicheva NK. Whispering vortices. PHYSICAL REVIEW LETTERS 2000; 84:151-154. [PMID: 11015857 DOI: 10.1103/physrevlett.84.151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/1999] [Indexed: 05/23/2023]
Abstract
Experiments indicating the excitation of whispering-gallery-type electromagnetic modes by a vortex moving in an annular Josephson junction are reported. At relativistic velocities the Josephson vortex interacts with the modes of the superconducting stripline resonator giving rise to novel resonances on the current-voltage characteristic of the junction. The experimental data are in good agreement with analysis and numerical calculations based on the two-dimensional sine-Gordon model.
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Neurohr K, Golubov AA, Klocke T, Kaufmann J, Schäpers T, Appenzeller J, Uhlisch D, Ustinov AV, Hollfelder M, Lüth H, Braginski AI. Properties of lateral Nb contacts to a two-dimensional electron gas in an In0.77Ga0.23As/InP heterostructure. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:17018-17028. [PMID: 9985834 DOI: 10.1103/physrevb.54.17018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ustinov AV, Kohlstedt H, Henne P. Giant Radiation Linewidth of Multifluxon States in Long Josephson Junctions. PHYSICAL REVIEW LETTERS 1996; 77:3617-3620. [PMID: 10062265 DOI: 10.1103/physrevlett.77.3617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Ustinov AV, Malomed BA. Fluxon-fluxon collision testing by a dissipative spot. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:9047-9049. [PMID: 9984629 DOI: 10.1103/physrevb.54.9047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Ustinov AV, Kohlstedt H. Interlayer fluxon interaction in Josephson stacks. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:6111-6114. [PMID: 9986620 DOI: 10.1103/physrevb.54.6111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Golubov AA, Malomed BA, Ustinov AV. Radiation linewidth of a long Josephson junction in the flux-flow regime. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:3047-3050. [PMID: 9986197 DOI: 10.1103/physrevb.54.3047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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50
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Quenter D, Ustinov AV, Lachenmann SG, Doderer T, Huebener RP, Müller F, Niemeyer J, Pöpel R, Weimann T. Spatially resolved flux flow in long-overlap Josephson tunnel junctions. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:6542-6550. [PMID: 9977190 DOI: 10.1103/physrevb.51.6542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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