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Dobrowolski T, Jarmoliński A. Josephson junction with variable thickness of the dielectric layer. Phys Rev E 2020; 101:052215. [PMID: 32575328 DOI: 10.1103/physreve.101.052215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
The dynamics of the fluxon in the Josephson junction is studied. The dielectric layer of the junction has a variable thickness. It is shown that the modified area of the junction acts on the fluxon as a potential barrier. The relation between the critical bias current and the thickness of the dielectric layer is analytically and numerically determined.
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Affiliation(s)
- T Dobrowolski
- Institute of Physics UP, Podchor ¸ ażych 2, 30-084 Cracow, Poland
| | - A Jarmoliński
- Institute of Physics UP, Podchor ¸ ażych 2, 30-084 Cracow, Poland
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2
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Magazzù L, Hänggi P, Spagnolo B, Valenti D. Quantum resonant activation. Phys Rev E 2017; 95:042104. [PMID: 28505843 DOI: 10.1103/physreve.95.042104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Indexed: 06/07/2023]
Abstract
Quantum resonant activation is investigated for the archetype setup of an externally driven two-state (spin-boson) system subjected to strong dissipation by means of both analytical and extensive numerical calculations. The phenomenon of resonant activation emerges in the presence of either randomly fluctuating or deterministic periodically varying driving fields. Addressing the incoherent regime, a characteristic minimum emerges in the mean first passage time to reach an absorbing neighboring state whenever the intrinsic time scale of the modulation matches the characteristic time scale of the system dynamics. For the case of deterministic periodic driving, the first passage time probability density function (pdf) displays a complex, multipeaked behavior, which depends crucially on the details of initial phase, frequency, and strength of the driving. As an interesting feature we find that the mean first passage time enters the resonant activation regime at a critical frequency ν^{*} which depends very weakly on the strength of the driving. Moreover, we provide the relation between the first passage time pdf and the statistics of residence times.
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Affiliation(s)
- Luca Magazzù
- Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86135 Augsburg, Germany
| | - Peter Hänggi
- Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86135 Augsburg, Germany
- Nanosystems Initiative Munich, Schellingstraße 4, D-80799 München, Germany
- Department of Physics, National University of Singapore, Singapore 117546
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
| | - Bernardo Spagnolo
- Dipartimento di Fisica e Chimica, Group of Interdisciplinary Theoretical Physics, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, Italy
- Radiophysics Department, Lobachevsky State University of Nizhny Novgorod, Russia
- Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Italy
| | - Davide Valenti
- Dipartimento di Fisica e Chimica, Group of Interdisciplinary Theoretical Physics, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, Italy
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3
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Pan C, Tan X, Yu Y, Sun G, Kang L, Xu W, Chen J, Wu P. Resonant activation through effective temperature oscillation in a Josephson tunnel junction. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:030104. [PMID: 19391880 DOI: 10.1103/physreve.79.030104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Indexed: 05/27/2023]
Abstract
We experimentally investigated the thermal escape from a metastable state in a Josephson tunnel junction subjected to an oscillating effective temperature. A minimum of the average escape time is observed at certain oscillation frequency. Our results confirm that the resonant activation can be caused not only by the oscillating barrier but also by the oscillating temperature. The linear dependence of the minimum average escape time on the resonant frequency suggests that the correlation between the oscillation and the escape process leads to the resonant escape.
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Affiliation(s)
- Cheng Pan
- Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
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4
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Hoang TB, Titova LV, Yarrison-Rice JM, Jackson HE, Govorov AO, Kim Y, Joyce HJ, Tan HH, Jagadish C, Smith LM. Resonant excitation and imaging of nonequilibrium exciton spins in single core-shell GaAs-AlGaAs nanowires. NANO LETTERS 2007; 7:588-95. [PMID: 17300213 DOI: 10.1021/nl062383q] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Nonequilibrium spin distributions in single GaAs/AlGaAs core-shell nanowires are excited using resonant polarized excitation at 10 K. At all excitation energies, we observe strong photoluminescence polarization due to suppressed radiative recombination of excitons with dipoles aligned perpendicular to the nanowire. Excitation resonances are observed at 1- or 2-LO phonon energies above the exciton ground states. Using rate equation modeling, we show that, at the lowest energies, strongly nonequilibrium spin distributions are present and we estimate their spin relaxation rate.
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Affiliation(s)
- Thang Ba Hoang
- Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221-0011, USA
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5
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Sun G, Dong N, Mao G, Chen J, Xu W, Ji Z, Kang L, Wu P, Yu Y, Xing D. Thermal escape from a metastable state in periodically driven Josephson junctions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:021107. [PMID: 17358313 DOI: 10.1103/physreve.75.021107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Revised: 11/30/2006] [Indexed: 05/14/2023]
Abstract
Resonant activation and noise-enhanced stability were observed in an underdamped real physical system, i.e., Josephson tunnel junctions. With a weak sinusoidal driving force applied, the thermal activated escape from a potential well underwent resonancelike behaviors as a function of the driving frequency. The resonances also crucially depended on the initial condition of the system. Numerical simulations showed good agreement with the experimental results.
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Affiliation(s)
- Guozhu Sun
- Research Institute of Superconductor Electronics, Department of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
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6
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Ma LC, Subramanian R, Huang HW, Ray V, Kim CU, Koh SJ. Electrostatic funneling for precise nanoparticle placement: a route to wafer-scale integration. NANO LETTERS 2007; 7:439-45. [PMID: 17298013 DOI: 10.1021/nl062727c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate a large-scale placement of nanoparticles through a scheme named "electrostatic funneling", in which charged nanoparticles are guided by an electrostatic potential energy gradient and placed on targeted locations with nanoscale precision. The guiding electrostatic structures are defined using current CMOS fabrication technology. The effectiveness of this scheme is demonstrated for a variety of geometries including one-dimensional and zero-dimensional patterns as well as three-dimensional step structures. Placement precision of 6 nm has been demonstrated using a one-dimensional guiding structure comprising alternatively charged lines with line width of approximately 100 nm. Detailed calculations using DLVO theory agree well with the observed long-range interactions and also estimate lateral forces as strong as (1-3) x 10(-7) dyn, which well explains the observed guided placement of Au nanoparticles.
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Affiliation(s)
- Liang-Chieh Ma
- Department of Materials Science and Engineering, The University of Texas at Arlington, Arlington, Texas 76019, USA
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7
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Tang Y, Jiang Y, Jia Z, Li B, Luo L, Xu L. Synthesis of CdSnO3·3H2O Nanocubes via Ion Exchange and Their Thermal Decompositions to Cadmium Stannate. Inorg Chem 2006; 45:10774-9. [PMID: 17173435 DOI: 10.1021/ic0613715] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Uniform crystalline CdSnO3.3H2O nanocubes with a 28-35 nm edge length have been obtained via the ion-exchange reaction of Na2Sn(OH)6 in a CdSO4 aqueous solution, assisted by ultrasonic treatment. Precursor Na2Sn(OH)6 crystals were prepared via hydrothermal treatment in an ethanol/water solution. The formation of CdSnO3.3H2O nanocubes resulted from the strain during the ion-exchange process. The influences of reaction conditions, such as ion-exchange (ultrasonic treatment) duration, solvent constitutes, surfactant, and pH on the formation of CdSnO3.3H2O crystals were described. Crystalline CdSnO3 and Cd2SnO4 have been obtained by thermal treatment at 300 and 500 degrees C, respectively, for 5 h under an inert-gas protecting condition using CdSnO3.3H2O nanocubes as the precursor. The cube shape of CdSnO3.3H2O was sustained after thermal decomposition to CdSnO3.
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Affiliation(s)
- Yiwen Tang
- Institute of Nano-science and Technology, Central China Normal University, Wuhan 430079, China.
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8
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Wang F, Dong A, Sun J, Tang R, Yu H, Buhro WE. Solution−Liquid−Solid Growth of Semiconductor Nanowires. Inorg Chem 2006; 45:7511-21. [PMID: 16961336 DOI: 10.1021/ic060498r] [Citation(s) in RCA: 296] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The serendipitously discovered solution-liquid-solid (SLS) mechanism has been refined into a nearly general synthetic method for semiconductor nanowires. Purposeful control of diameters and diameter distributions is achieved. The synthesis proceeds by a solution-based catalyzed-growth mechanism in which nanometer-scale metallic droplets catalyze the decomposition of metallo-organic precursors and crystalline nanowire growth. Related growth methods proceeding by the analogous vapor-liquid-solid (VLS) and supercritical fluid-liquid-solid (SFLS) mechanisms are known, and the relative attributes of the methods are compared. In short, the VLS method is most general and appears to afford nanowires of the best crystalline quality. The SLS method appears to be advantageous for producing the smallest nanowire diameters and for variation and control of surface ligation. The SFLS method may represent an ideal compromise. Recent results for SLS growth are summarized.
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Affiliation(s)
- Fudong Wang
- Department of Chemistry and Center for Materials Innovation, Washington University, St. Louis, Missouri 63130-4899, USA
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9
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Liu Y, Li H, Tu D, Ji Z, Wang C, Tang Q, Liu M, Hu W, Liu Y, Zhu D. Controlling the Growth of Single Crystalline Nanoribbons of Copper Tetracyanoquinodimethane for the Fabrication of Devices and Device Arrays. J Am Chem Soc 2006; 128:12917-22. [PMID: 17002388 DOI: 10.1021/ja0636183] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, (1) a simple and controllable method to synthesize single crystalline nanoribbons of CuTCNQ in a large area was demonstrated by using a physical and chemical vapor combined deposition technique. (2) Nanoribbons synthesized by this method were identified to belong to phase I. (3) Devices and device arrays of nanoribbons were in situ fabricated by this method using gap electrodes and gap electrode arrays. (4) Current-voltage characteristics of crystalline devices and device arrays of nanoribbons exhibited semiconductor properties, and this conclusion was further confirmed by the results of devices based on an individual nanoribbon or microribbon of CuTCNQ (phase I). The controllable synthesis of nanoribbons for the in situ fabrication of crystalline nanodevices and device arrays will be attractive for nanoelectronics. Moreover, semiconductor current-voltage characteristics of the nanoribbons will be beneficial to the understanding of CuTCNQ.
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Affiliation(s)
- Yaling Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China
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10
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Chen YB, Chen L, Wu LM. Structure-Controlled Solventless Thermolytic Synthesis of Uniform Silver Nanodisks. Inorg Chem 2005; 44:9817-22. [PMID: 16363851 DOI: 10.1021/ic051246d] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Monodisperse silver nanodisks are synthesized on the gram scale from a well-characterized layered silver thiolate precursor via thermolysis at 180-225 degrees C under a N(2) atmosphere. XRD, TEM, HRTEM, and AFM analyses indicate that the nanodisks generated at 180 degrees C over 2 h have an average diameter of about 16.1 nm (sigma = +/-12%) and a thickness of 2.3 nm (sigma = +/-14%), and they lie on their (111) faces. The disk shape is considered to be predestined by the crystal structure of the precursor. Important aspects regarding the stability of the precursor, the thermolysis temperature, and the annealing time, as well as a possible conversion mechanism, are discussed.
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Affiliation(s)
- Yu-Biao Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, PR China
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11
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Kim JY, Hiramatsu H, Osterloh FE. Planar Polarized Light Emission from CdSe Nanoparticle Clusters. J Am Chem Soc 2005; 127:15556-61. [PMID: 16262420 DOI: 10.1021/ja0541377] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes synthesis and optical properties of planar clusters of CdSe nanocrystals. The clusters emit linearly polarized light in the plane of the cluster. The emission wavelength of the clusters can be adjusted between 568 and 639 nm with the size of the CdSe nanocrystals. Planar CdSe microclusters were synthesized by reaction of trioctylphosphine oxide-coated CdSe/CdS nanocrystals with 3-aminopropylsilyl-modified Ca(2)Nb(3)O(10) nanosheets in THF. The clusters are 3.92 +/- 1.18 mum length/width and 91 +/- 37 nm thickness, and they consist of alternating layers of Ca(2)Nb(3)O(10) to which CdSe nanocrystals are attached with densities of 5300 +/-310 particles per side of a single Ca(2)Nb(3)O(10) sheet. The chemical inertness of the clusters in coordinating solvents suggests covalent interactions between the aminopropyl groups and CdSe nanocrystals. Upon excitation at lambda(exc) = 400 nm, the clusters emit green (568 nm), orange (589 nm), or red (639 nm) light, depending on the size of the CdSe crystals. The light is emitted preferentially in the cluster plane and it is linearly polarized along the cluster edges. Combined fluorescence microscopy and atomic force microscopy reveal that the directional emission efficiency depends linearly on the thickness of the clusters, which varies between 70 and 180 nm. The ability to manipulate the direction and polarization of the photoemission of CdSe nanoparticles via assembly into 2D structures is of interest for applications of these and similar structures in advanced optical materials and devices.
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Affiliation(s)
- Jin Young Kim
- Department of Chemistry, University of California-Davis, Davis, CA 95616, USA
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12
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Mallick K, Witcomb MJ, Dinsmore A, Scurrell MS. Fabrication of a metal nanoparticles and polymer nanofibers composite material by an in situ chemical synthetic route. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:7964-7. [PMID: 16089406 DOI: 10.1021/la050534j] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
This work demonstrated a facile route for the synthesis of poly(3,5-dimethyl aniline) nanofibers by polymerization of 3,5-dimethyl aniline using Pd-acetate as the oxidant. The reduction of Pd ion is accompanied by oxidative polymerization of 3,5-dimethyl aniline, leading to a metal-polymer composite material. Palladium nanoparticles (approximately 2 nm) are uniformly distributed throughout the polymer that makes the composite material a unique morphology. The resultant composite material was characterized by means of different techniques. IR and Raman spectra provide the information on the chemical structure of the polymer. TEM images show the morphology of the polymer and size of the metal particles.
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Affiliation(s)
- Kaushik Mallick
- Molecular Sciences Institute, School of Chemistry, Electron Microscope Unit, University of the Witwatersrand, Private Bag 3, WITS 2050 South Africa.
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13
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van Vugt LK, Veen SJ, Bakkers EPAM, Roest AL, Vanmaekelbergh D. Increase of the Photoluminescence Intensity of InP Nanowires by Photoassisted Surface Passivation. J Am Chem Soc 2005; 127:12357-62. [PMID: 16131216 DOI: 10.1021/ja051860o] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As-grown single-crystal InP nanowires, covered with a surface oxide, show a photoluminescence efficiency that strongly varies from wire to wire. We show that the luminescence efficiency of single-crystal InP nanowires can be improved by photoassisted wet chemical etching in a butanol solution containing HF and the indium-coordinating ligand trioctylphosphine oxide. Electron-hole photogeneration, electron scavenging, and oxidative dissolution combined with surface passivation by the indium-coordinating ligand are essential elements to improve the luminescence efficiency. Time traces of the luminescence of surface-passivated wires show strong oscillations resembling the on-off blinking observed with single quantum dots. These results reflect the strong influence of a single or a few nonradiative recombination center(s) on the luminescence properties of an entire wire.
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Affiliation(s)
- Lambert K van Vugt
- Debye Institute, Condensed Matter and Interfaces, Utrecht University, Post Office Box 80 000, 3508 TA Utrecht, The Netherlands.
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14
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Feng X, Yuan X, Sekiguchi T, Lin W, Kang J. Aligned Zn−Zn2SiO4 Core−Shell Nanocables with Homogenously Intense Ultraviolet Emission at 300 nm. J Phys Chem B 2005; 109:15786-90. [PMID: 16853004 DOI: 10.1021/jp0514980] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aligned coaxial nanocables were grown on Si substrates by a vapor-deposition technique. The lengths of the nanocables increased as the distance between the substrate and the source decreased. The nanocables were characterized as homogeneously crystallized shells of about 25 nm thick, diameters of about 100 nm, and round top ends. It was found that the shell emits an intense middle-ultraviolet about 300 nm at room temperature. This emission was attributed to the thin double-layer structure in the Zn-Zn2SiO4 core-shell nanocable where the Zn2SiO4 shell has the potential to serve as more ideal luminophors. The results demonstrated that the nanocable density could be changed by altering nucleation density at the steps on the substrate surface. The unique growth manner described herein provides a new technique for the homogeneous crystallization of Zn-Zn2SiO4 core-shell nanocables.
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Affiliation(s)
- Xia Feng
- Department of Physics and Photonics Research Center, Xiamen University, Xiamen 361005, People's Republic of China
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15
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Kim JY, Osterloh FE. ZnO−CdSe Nanoparticle Clusters as Directional Photoemitters with Tunable Wavelength. J Am Chem Soc 2005; 127:10152-3. [PMID: 16028910 DOI: 10.1021/ja052735f] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reaction of 3-aminopropylsilyl-modified ZnO microrods with trioctylphosphineoxide-coated CdSe/CdS core/shell nanocrystals in THF produces rod-shaped nanoparticle clusters that show directional photoemission that can be tuned with the size of the CdSe nanocrystals. The observed waveguiding effect of these microstructures is due to total internal reflection of light at the cluster-air interface.
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Affiliation(s)
- Jin Young Kim
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, USA
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16
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Millstone JE, Park S, Shuford KL, Qin L, Schatz GC, Mirkin CA. Observation of a Quadrupole Plasmon Mode for a Colloidal Solution of Gold Nanoprisms. J Am Chem Soc 2005; 127:5312-3. [PMID: 15826156 DOI: 10.1021/ja043245a] [Citation(s) in RCA: 427] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis and optical properties of single crystalline gold nanoprisms have been investigated. A three-step mediated seed growth process in an aqueous solution generated gold nanoprisms with a relatively homogeneous size distribution. The purity of these nanostructures has allowed us to observe a weak quadrupole resonance in addition to a strong dipole resonance associated with these novel structures. The experimental optical spectra agree with discrete dipole approximation calculations that have been modeled from the dimensions of gold nanoprisms produced in this synthesis.
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Affiliation(s)
- Jill E Millstone
- Department of Chemistry and Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
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17
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Hanrath T, Korgel BA. Influence of Surface States on Electron Transport through Intrinsic Ge Nanowires. J Phys Chem B 2005; 109:5518-24. [PMID: 16851592 DOI: 10.1021/jp044491b] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Solution-grown single-crystal Ge nanowires were used as conductive channels in field effect transistor devices to study the influence of surface states on their electron transport properties. Nanowires contacted with Pt electrodes using focused ion beam metal deposition exhibited linear current-voltage (IV) curves at room temperature with apparent resistivities ranging from 10(1) to 10(-1) Omega cm. In all cases, the nanowire conductance decreased with positive external electric fields applied perpendicular to the nanowire surface by a gate electrode, characteristic of p-type carrier accumulation at the nanowire surface. The field-induced change in conductance exhibited a time-dependent relaxation, with response time and magnitude of current decrease that depended on the nanowire surface chemistry. Nanowires treated with an organic passivation layer using a thermally initiated hydrogermylation reaction exhibited 2 orders of magnitude slower current relaxation and a smaller decrease in current relative to "bare" nanowires with oxidized surfaces.
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Affiliation(s)
- Tobias Hanrath
- Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, TX 78712-1062, USA
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18
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Abstract
Monodisperse silver nanocubes with edge length of 55 +/- 5 nm were, for the first time, synthesized in water on the basis of HTAB-modified silver mirror reaction at 120 degrees C (HTAB, n-hexadecyltrimethylammonium bromide). The individual nanocube was crystallographically well defined with a single crystal bonded by six {200} facets. The nanocubes were soluble to form stable aqueous solutions and had a strong tendency to assemble into two-dimensional arrays with regular checked pattern on substrate.
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Affiliation(s)
- Dabin Yu
- Center for Carbon-Rich Molecular and Nano-Scale Metal-Based Materials Research and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
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19
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Behrend CJ, Anker JN, McNaughton BH, Brasuel M, Philbert MA, Kopelman R. Metal-Capped Brownian and Magnetically Modulated Optical Nanoprobes (MOONs): Micromechanics in Chemical and Biological Microenvironments. J Phys Chem B 2004. [DOI: 10.1021/jp040125g] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Caleb J. Behrend
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
| | - Jeffrey N. Anker
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
| | - Brandon H. McNaughton
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
| | - Murphy Brasuel
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
| | - Martin A. Philbert
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
| | - Raoul Kopelman
- Department of Chemistry and School of Public Health, University of Michigan Ann Arbor, Michigan 48109-1055, and Chemistry Department, Colorado College, Colorado Springs, Colorado 80903
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20
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Yu Y, Nakada D, Lee JC, Singh B, Crankshaw DS, Orlando TP, Berggren KK, Oliver WD. Energy relaxation time between macroscopic quantum levels in a superconducting persistent-current qubit. PHYSICAL REVIEW LETTERS 2004; 92:117904. [PMID: 15089174 DOI: 10.1103/physrevlett.92.117904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2003] [Indexed: 05/24/2023]
Abstract
We measured the intrawell energy relaxation time tau(d) approximately 24 micros between macroscopic quantum levels in the double well potential of a Nb persistent-current qubit. Interwell population transitions were generated by irradiating the qubit with microwaves. Zero population in the initial well was then observed due to a multilevel decay process in which the initial population relaxed to lower energy levels during the driven transitions. The decoherence time, estimated from tau(d) within the spin-boson model, is about 20 micros for this configuration with a Nb superconducting qubit.
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Affiliation(s)
- Yang Yu
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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21
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Martinis JM. Course 13 Superconducting qubits and the physics of Josephson junctions. QUANTUM ENTANGLEMENT AND INFORMATION PROCESSING, ÉCOLE D' ÉTÉ DE PHYSIQUE DES HOUCHES SESSION LXXIX 2004. [DOI: 10.1016/s0924-8099(03)80037-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Barrelet CJ, Wu Y, Bell DC, Lieber CM. Synthesis of CdS and ZnS nanowires using single-source molecular precursors. J Am Chem Soc 2003; 125:11498-9. [PMID: 13129343 DOI: 10.1021/ja036990g] [Citation(s) in RCA: 396] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-source molecular precursors were used to synthesize II-VI compound semiconductor nanowires for the first time. Cadmium sulfide and zinc sulfide nanowires were prepared using cadmium diethyldithiocarbamate, Cd(S2CNEt2)2, and zinc diethyldithiocarbamate, Zn(S2CNEt2)2, respectively, as precursors in a gold nanocluster-catalyzed vapor-liquid-solid growth process. High-resolution transmission electron microscopy studies show that the CdS and ZnS nanowires are single-crystal wurtzite structures with stoichiometric compositions. In addition, photoluminescence measurements demonstrate that these nanowires exhibit high-quality optical properties. The applicability of our approach to the synthesis of other compound and alloy semiconductors nanowires as well as nanowire heterostructures of these materials is discussed.
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Affiliation(s)
- Carl J Barrelet
- Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138, USA
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Yu Y, Han S. Resonant escape over an oscillating barrier in underdamped Josephson tunnel junctions. PHYSICAL REVIEW LETTERS 2003; 91:127003. [PMID: 14525391 DOI: 10.1103/physrevlett.91.127003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2003] [Indexed: 05/24/2023]
Abstract
The escape from a metastable state over an oscillating barrier of an underdamped Josephson tunnel junction has been experimentally investigated with oscillation frequency well separated from the plasma frequency of the junction. The resonant escape, namely, a minimum of the average escape time as a function of the oscillation frequency, was observed. For the oscillation frequency much smaller than the "resonant frequency," the average escape time is the average of the times required to cross over each of the barriers. On the other hand, for the oscillation frequency much greater than the "resonant frequency," the average escape time is that required to cross the average barrier.
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Affiliation(s)
- Yang Yu
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
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24
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Martinis JM, Nam S, Aumentado J, Urbina C. Rabi oscillations in a large Josephson-junction qubit. PHYSICAL REVIEW LETTERS 2002; 89:117901. [PMID: 12225170 DOI: 10.1103/physrevlett.89.117901] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2002] [Indexed: 05/23/2023]
Abstract
We have designed and operated a circuit based on a large-area current-biased Josephson junction whose two lowest energy quantum levels are used to implement a solid-state qubit. The circuit allows measurement of the qubit states with a fidelity of 85% while providing sufficient decoupling from external sources of relaxation and decoherence to allow coherent manipulation of the qubit state, as demonstrated by the observation of Rabi oscillations. This qubit circuit is the basis of a scalable quantum computer.
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Affiliation(s)
- John M Martinis
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305-3328, USA.
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25
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Li SX, Yu Y, Zhang Y, Qiu W, Han S, Wang Z. Quantitative study of macroscopic quantum tunneling in a dc SQUID: a system with two degrees of freedom. PHYSICAL REVIEW LETTERS 2002; 89:098301. [PMID: 12190444 DOI: 10.1103/physrevlett.89.098301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2001] [Indexed: 05/23/2023]
Abstract
To test whether the theory of macroscopic quantum tunneling (MQT) is applicable to systems with 2 degrees of freedom, we experimentally investigated the switching current distribution of a dc SQUID. Using sample parameters determined from measurements at T=4.2 K, we are able to make quantitative comparison to the theories from 8 mK to 4.2 K. The excellent agreement between the data and the MQT theory demonstrates that tunneling from the zero-voltage state of the dc SQUID is well described by the quantum mechanics.
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Affiliation(s)
- Shao-Xiong Li
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
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26
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Peña DJ, Mbindyo JKN, Carado AJ, Mallouk TE, Keating CD, Razavi B, Mayer TS. Template Growth of Photoconductive Metal−CdSe−Metal Nanowires. J Phys Chem B 2002. [DOI: 10.1021/jp0256591] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David J. Peña
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jeremiah K. N. Mbindyo
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Anthony J. Carado
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Thomas E. Mallouk
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Christine D. Keating
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Baharak Razavi
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Theresa S. Mayer
- Departments of Chemistry and Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
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27
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Averin DV. Quantum nondemolition measurements of a qubit. PHYSICAL REVIEW LETTERS 2002; 88:207901. [PMID: 12005606 DOI: 10.1103/physrevlett.88.207901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2002] [Indexed: 05/23/2023]
Abstract
The concept of quantum nondemolition (QND) measurement is extended to coherent oscillations in an individual two-state system. Such a measurement enables direct observation of an intrinsic spectrum of these oscillations avoiding the detector-induced dephasing that affects the standard (non-QND) measurements. The suggested scheme can be realized in Josephson-junction qubits which combine flux and charge dynamics.
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Affiliation(s)
- D V Averin
- Department of Physics and Astronomy, SUNY Stony Brook, Stony Brook, New York 11794-3800, USA
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28
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Vion D, Aassime A, Cottet A, Joyez P, Pothier H, Urbina C, Esteve D, Devoret MH. Manipulating the quantum state of an electrical circuit. Science 2002; 296:886-9. [PMID: 11988568 DOI: 10.1126/science.1069372] [Citation(s) in RCA: 1302] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We have designed and operated a superconducting tunnel junction circuit that behaves as a two-level atom: the "quantronium." An arbitrary evolution of its quantum state can be programmed with a series of microwave pulses, and a projective measurement of the state can be performed by a pulsed readout subcircuit. The measured quality factor of quantum coherence Qphi approximately 25,000 is sufficiently high that a solid-state quantum processor based on this type of circuit can be envisioned.
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Affiliation(s)
- D Vion
- Quantronics Group, Service de Physique de l'Etat Condensé, Direction des Sciences de la Matière, Commissariat à l'Energie Atomique-Saclay, 91191 Gif-sur-Yvette, France.
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29
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Yu Y, Han S, Chu X, Chu SI, Wang Z. Coherent temporal oscillations of macroscopic quantum states in a Josephson junction. Science 2002; 296:889-92. [PMID: 11988569 DOI: 10.1126/science.1069452] [Citation(s) in RCA: 569] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report the generation and observation of coherent temporal oscillations between the macroscopic quantum states of a Josephson tunnel junction by applying microwaves with frequencies close to the level separation. Coherent temporal oscillations of excited state populations were observed by monitoring the junction's tunneling probability as a function of time. From the data, the lower limit of phase decoherence time was estimated to be about 5 microseconds.
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Affiliation(s)
- Yang Yu
- Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
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