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Topic: Josephson junction


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In the News (Fri 22 Mar 19)

  
  SQUID Magnetometer and Josephson Junctions
One of the discoveries associated with Josephson junctions was tha flux is quantized in units
Devices based upon the characteristics of a Josephson junction are valuable in high speed circuits.
Parallel Josephson junctions are used in SQUID devices for the detection of minute magnetic fields.
hyperphysics.phy-astr.gsu.edu /hbase/solids/squid.html   (604 words)

  
  Josephson junction - Wikipedia, the free encyclopedia
Josephson and first made by John Rowell and Philip Anderson, are quantum-mechanical circuit elements of superconducting devices.
In overdamped junctions, the barrier is conducting (normal metal or superconductor bridge).
The barrier of an underdamped junction is an insulator.
www.wikipedia.org /wiki/Josephson_junction   (510 words)

  
 Josephson Junctions
The Josephson junction   quantum computer was demonstrated in April 1999 by Nakamura, Pashkin and Tsai of NEC Fundamental Research Laboratories in Tsukuba, Japan    [
So a Josephson junction quantum computer is no longer a stuff of theoretical considerations, but a practical reality.
Like most other junctions, the Josephson junction is also a capacitor, which is charged by the current that flows through it.
beige.ucs.indiana.edu /M743/node22.html   (371 words)

  
 Josephson effect - Wikipedia, the free encyclopedia
It is also speculated that Josephson junctions may allow the realisation of qubits, the key elements of an eventual quantum computer.
The current flow is known as the Josephson current and the quantum tunneling of the insulator by the Cooper pairs is the Josephson effect.
This effect is used for the representation and maintenance of the SI voltage, where an alternating phase is induced by radiation of microwaves with a well-known frequency onto the Josephson junction.
en.wikipedia.org /wiki/Josephson_effect   (484 words)

  
 Encyclopedia: Josephson junction   (Site not responding. Last check: 2007-10-14)
Brian David Josephson (born Cardiff, UK, January 4, 1940) is a British physicist whose discovery of the Josephson effect while a 22_year_old graduate student won him a share (with Leo Esaki and Ivar Giaever) of the 1973 Nobel Prize for Physics.
In the AC Josephson effect, a Josephson junction will oscillate with a characteristic frequency which is proportional to the voltage across the junction.
Josephson junctions, first developed by (Click link for more info and facts about B. Josephson) B. In overdamped junctions, the barrier is conducting (normal metal or superconductor bridge).
www.nationmaster.com /encyclopedia/Josephson-junction   (1400 words)

  
 [No title]   (Site not responding. Last check: 2007-10-14)
As long as the Josephson junction adopts a closed form, it is possible to trap an elementary quantum of magnetic flux (fluxon) in the junction.
In closed-form Josephson junctions, a fluxon has a potential energy at each position in the junction that is significantly determined by the width and shape of the Josephson junction at that position.
Fabrication of a Josephson junction with precise closed-form geometry is accomplished, in part, by using the superconducting and insulating layers as a mask for a photoresist layer.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/19686.030306&ELEMENT_SET=DECL   (6625 words)

  
 [No title]   (Site not responding. Last check: 2007-10-14)
The grain boundary Josephson junction is manufactured by the method comprising (i) forming a superconducting layer on a substrate, (ii) patterning the superconducting layer thereby forming the grain boundary Josephson junction on the substrate, and (iii) annealing the grain boundary Josephson junction on the
Josephson junctions 31 that are less than the width F of a facet 830 are desirable because their electrical properties are not adversely affected by faceting.
To form a Josephson junction 31 in a YBCO layer that is not affected by the defects of the YBCO necessitates the formation of a submicron GBJJ (e.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/19685.030306&ELEMENT_SET=DECL   (9283 words)

  
 Synchronizing interface circuit between semiconductor element circuit and a Josephson junction element circuit - US ...   (Site not responding. Last check: 2007-10-14)
In an interface circuit transferring a data signal from a semiconductor element circuit to a Josephson junction element circuit, a first unit detects a change switching of a first clock signal supplied from the semiconductor element circuit, and generates a second clock signal in response to the change of a first clock signal.
Conventionally, in the experiments for testing the operation of a Josephson junction element circuit, a signal pattern for testing the Josephson junction element circuit is generated by a signal generator formed with a semiconductor circuit and is applied thereto.
Further, Josephson elements are required to be operated in synchronism with a clock signal having a frequency higher than that of a clock signal with which semiconductor elements are synchronized.
www.patentstorm.us /patents/5315180.html   (7728 words)

  
 Josephson junction - a Whatis.com definition   (Site not responding. Last check: 2007-10-14)
A Josephson junction is a type of electronic circuit capable of switching at very high speeds when operated at temperatures approaching absolute zero.
A Josephson junction is made up of two superconductors, separated by a nonsuperconducting layer so thin that electrons can cross through the insulating barrier.
The Josephson effect is influenced by magnetic fields in the vicinity, a capacity that enables the Josephson junction to be used in devices that measure extremely weak magnetic fields, such as superconducting quantum interference devices (SQUIDs).
whatis.techtarget.com /gDefinition/0,294236,sid44_gci815055,00.html   (332 words)

  
 Method of modifying the performance characteristics of a Josephson junction - Patent 4163156
The details of the Josephson junctions themselves are known in the art and let it suffice here to say that each junction, e.g., 14, comprises a thin tunneling barrier layer between a pair of conductors, e.g., 19 and 20.
The resistance of the junction in the resistance is a critical characteristic of the junction behavior.
The usual tunneling barrier 29 of the Josephson junction is disposed between the conductors 26 and 28.
www.freepatentsonline.com /4163156.html   (2765 words)

  
 Edward Goldobin -- Research
Recently it was discovered that in Josephson junctions made of cuprate superconductors or in Josephson junctions with ferromagnetic barrier the critical current may be negative.
Such a stack of coupled Josephson junctions closely resembles the structure of cuprate superconductors such as BSCCO which is under intensive investigation since the discovery of cuprate family of high temperature superconductors.
Josephson junctions are fast devices and therefore may rectify noise in the wide frequency range from 0 up to 100 GHz.
www.geocities.com /e_goldobin/research.htm   (691 words)

  
 [No title]   (Site not responding. Last check: 2007-10-14)
The Josephson junction was predicted by Brian Josephson in 1962, for which he won the Nobel Prize for Physics in 1973.
These so-called "intrinsic" Josephson junctions were first demonstrated in single crystals by our collaborators in Erlangen in 1992.
Interest in the quantum properties of Josephson junctions has been rekindled over the last few years by the prospect of developing a solid-state quantum computer.
www.ee.ucl.ac.uk /~pwarburt/jj.htm   (428 words)

  
 LNE, Quantum metrology : the josephson effect, Research and Development
DC Josephson effect: If no voltage is applied to the junction terminals, a direct current - a current of Cooper pairs Ij, - flows through the junction up to a critical value Ic, which depends on the geometry, temperature and magnetic field (Fig.2a).
The definition of the volt in the International System of Units (SI) is as follows: "The volt is the electromotive force between two points of a conductor carrying a current of 1 ampere when the power dissipated between the two points is 1 watt" [3].
Development of voltage standards based on the Josephson effect is closely linked to the advances in junction manufacture and nanotechnologies (nanofabrication techniques such as thin layer deposition and microlithography).
www.lne.fr /en/r_and_d/electrical_metrology/josephson_effect_ej.shtml   (1369 words)

  
 High gain non-linear threshold input Josephson junction logic circuit - Patent 4559459
Both of the above-mentioned Josephson junction logic circuits are complex and display linear threshold characteristics which limit the gain and the operating region of the devices in the output stage.
The Josephson junction amplifying circuit 10A is identical to the previously described amplifier circuit 10 and carries the same designations for the same elements.
These Josephson junction devices 38, 39 and 41 are switched into their voltage state in order to switch Josephson junction device J.sub.2 and then Josephson junction device J.sub.3 into the voltage state.
www.freepatentsonline.com /4559459.html   (3404 words)

  
 Theory   (Site not responding. Last check: 2007-10-14)
A Josephson junction, which is a thin layer of insulator sandwiched between two layers of superconductor, can be used to provide an environment in which such small fluxes have a significant effect on the overall current, allowing them to be measured.
The junction we will be using is the niobium-aluminum oxide-niobium junction (Nb-AlO-Nb): it consists of 2 niobium wires crossing each other at right angles, with a thin (~30Å) layer of AlO in between (see figure 2).
L is the length of the junction, and k is an arbitrary wave number.
mxp.physics.umn.edu /s02/Projects/Josephson/theory.htm   (869 words)

  
 Process for preparing Josephson junction device having weak link of artificial grain boundary - US Patent 5439875   (Site not responding. Last check: 2007-10-14)
A Josephson junction device comprises a single crystalline substrate including a principal surface having a first and a second regions of which at least lattice distance of exposed lattices are slightly different from each other and an oxide superconductor thin film formed on the principal surface of the substrate.
The point contact type junction has been formed of two oxide superconductor thin films which are in contact with each other in a extremely small area which constitutes the weak link of the Josephson junction.
In order to manufacture the artificial grain boundary type Josephson junction device, in a prior art, the same two substrates were joined so as to form a substrate of which the crystalline directions of each sides were different from each other.
www.patentstorm.us /patents/5439875.html   (3707 words)

  
 KONSTANTIN K
"Pulses with Preoscillations in a Time-Delay Structure with a Josephson Junction" (with V.K. Kornev).
"Dynamics of Josephson Tunnel Junctions with a Finite-Width Riedel Peak" (with S.I. Turovets and A.B. Zorin).
Josephson Junctions and Prospects of their RSFQ VLSI Applications” (with Y. Naveh and D. Averin).
rsfq1.physics.sunysb.edu /~likharev/personal/PubList.html   (3949 words)

  
 Grundlagen der Materialwissenschaft V
We compare the current patterns, calculated for various distances to the adjacent bulk magnets, both with those in an isolated Josephson junction and those in magnetically shielded films without a junction.
The density of the supercurrent across the Josephson junction is given by the relation
The current distribution over a long, shielded Josephson junction in the strip again shows current peaks near the edges of the junction, their height however diminishing and the average current density simultaneously increasing when the distance between the centre of the junction and the adjacent magnets is reduced (Fig.
www.tu-darmstadt.de /fb/ms/fg/tgm/Magnetic_02.html   (507 words)

  
 Quantum Computing
Josephson junctions are electrical circuit elements which resemble capacitors.
The current that flows through the Josephson junction is proportional to the sine of the quantum mechanical phase difference δ across the junction.
Microwav current lines are capacitively coupled to the junction while a dc bias coil is placed some distance from the “qubit loop.” For an applied magnetic flux through the loop, the potential energy stored in the Josephson junction as a function of the superconducting phase difference δ is shown in Figure 2(b).
emtech.boulder.nist.gov /div817b/whatwedo/qcomputing/qcomputing.htm   (2129 words)

  
 Josephson Junction Series Arrays   (Site not responding. Last check: 2007-10-14)
Josephson Junction--take two pieces of a superconducting material and sandwich something that isn't superconducting between them (choose from a normal-conductor, semi-conductor or non-conductor).
To make the circuit useful, all of the junctions must oscillate together.
A Josephson junction series array parable--Go to a hilly countryside.
www.physics.ohio-state.edu /~jkenth/jjsa.html   (153 words)

  
 Josephson, Brian D.
While still an undergraduate, Josephson became interested in superconductivity, and he began to explore the properties of a junction between two superconductors that later came to be known as a Josephson junction.
Josephson extended earlier work in tunneling, the phenomenon by which electrons functioning as radiated waves can penetrate solids, done by Esaki and Giaever.
Applying Josephson's discoveries with superconductors, researchers at International Business Machines Corporation had assembled by 1980 an experimental computer switch structure, which would permit switching speeds from 10 to 100 times faster than those possible with conventional silicon-based chips, increasing data processing capabilities by a vast amount.
www.britannica.com /nobel/micro/306_81.html   (391 words)

  
 Josephson junction in a thin film   (Site not responding. Last check: 2007-10-14)
The phase difference \varphi (y) for a vortex at a line Josephson junction in a thin film attenuates at large distances as a power law, unlike the case of a bulk junction where it approaches exponentially the constant values at infinities.
The field of a Josephson vortex is a superposition of fields of standard Pearl vortices distributed along the junction with the line density \varphi'(y)/2\pi.
We study the integral equation for \varphi (y) and show that the phase is sensitive to the ratio \ell/\Lambda, where \ell=\lambda_J^2/\lambda_L, \Lambda=2\lambda_L^2/d, \lambda_L and \lambda_J are the London and Josephson penetration depths, and d is the film thickness.
flux.aps.org /meetings/YR01/MAR01/abs/S8180005.html   (156 words)

  
 Branimir Vasilić (elektropionir)
Josephson junctions consist of two superconductors weakly coupled together by a thin non-superconducting layer.
The junctions have very interesting properties: a) they can support a constant current without developing a voltage across them, as long as the current is below some critical value.
b) when there is a voltage across a junction the current through it oscillates with a frequency proportional to the voltage.
mywebpages.comcast.net /brana7/research.html   (518 words)

  
 That Miraculous Josephson Junction   (Site not responding. Last check: 2007-10-14)
Josephson junctions and mercury solder aren't a bad solution for the cold of the moon's surface.
My PC seems to be little more than a glorified space-heater at times, and the really big machines, Crays and the like, need their own supplies of liquid nitrogen to keep from melting.
The Josephson junction itself produces a constant current for a range of voltages, and then acts more like an ordinary conductor outside that range.
www.cyberartsweb.org /cpace/cpace/scifi/rucker/pillsbury.html   (866 words)

  
 J. Kent Harbaugh's Dissertation Page   (Site not responding. Last check: 2007-10-14)
The second system is a linear array of Josephson junctions within an electromagnetic cavity.
For the junction array in the cavity, we find there is a threshold number N_c of junctions required for junction coherence.
For an array of N junctions, for N > N_c, we have the energy of the photon mode goes as E_photon goes as N^2.
www.physics.ohio-state.edu /~jkenth/writing/dissertation.html   (353 words)

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