New nanotechnology converts heat into power when it’s needed most

nanotechweb.org: your news

Signor Marconi’s Magic Box: The Most Remarkable Invention Of The 19th Century & The Amateur Inventor Whose Genius Sparked A Revolution

Signor Marconi’s Magic Box: The Most Remarkable Invention Of The 19th Century & The Amateur Inventor Whose Genius Sparked A Revolution

• ISBN13: 9780306813788
• Condition: USED – VERY GOOD
• Notes:

The world at the turn of the twentieth century was in the throes of “Marconi-mania”-brought on by an incredible invention that no one could quite explain, and by a dapper and eccentric figure (who would one day win the newly minted Nobel Prize) at the center of it all. At a time when the telephone, telegraph, and electricity made the whole world wonder just what science would think of next, the startling answer had come in 1896 in the form of two mysterious wooden boxes containing a device Marconi had rigged up to transmit messages “through the ether.” It was the birth of the radio, and no scientist in Europe or America, not even Marconi himself, could at first explain how it worked…it just did.

Here is a rich portrait of the man and his era-a captivating tale of British blowhards, American con artists, and Marconi himself-a character par excellence, who eventually winds up a virtual prisoner of his worldwide fame and fortune.

Rating: (out of 8 reviews)

List Price: $ 15.00

Price: $ 2.99

Superconductivity most realistic technology for quantum computers

 

Superconductivity most realistic technology for quantum computers.

 

Rabiya Tanveer,Dept. of physics,chaitanya Degree & P.G College,Warangal,A.P,India.
Affilation:1.Nano Science & technology consortium,Noida,U.P,India.
                2.photonics21-european technology platform.

Abstract: This article describes the applications of phenomenon of superconductivity in nanochips ,which could the basis for most realistic approach for quantum computing. Nano scale superconducting electronic devices could potentially revolutionized the electronics in an unimaginable way.

Superconductivity and magnetism appear in condensed matter due to strong electron-electron correlation. Since superconductivity is suppressed by magnetic field, magnetism, with its spontaneously generated high internal magnetic field, is normally considered as an antagonistic state.

Superconductivity was discovered in 1911 .At that time superconductivity is the subject of an enormous amount of research in physics, It is a surprising, new, and very important phenomenon. Superconducting materials have an electrical resistance of zero, and so can carry large electrical currents without power dissipation or heat generation.The phenomenon of Superconductivity is considered as a macroscopic phenomenon that it exists at the molecular scale, which opens up a novel route for studying this phenomenon.

 

Superconductors are used in various applications ranging from supercomputers to brain imaging devices. The phenomenon of superconductivity has various applications  for eg : in superconducting quantum interference devices and in physical realizations of qubits. Single-electron transistors are often constructed of superconducting materials which functions on  Josephson effect to achieve novel effects. The resulting device is called a “superconducting single-electron transistor.

 

Superconductivity has a lot of promising work in low-dimensional electron gases, carbon nanotubes, and nanowires.Nanotechnology has undoubtedly emerged as one of today’s hottest fields. It helps engineers and physicist to understand  nanoscale electronic devices eg;Nano scale FETs .Nanoscale FETs could potentially push the moore’s law much farther and helps to develop in powerful computers.

 

Nano scale superconducting electronic devices could potentially revolutionized the electronics in an unimaginable way. For example, transistors are important in digital circuits because they utilize the electronic properties of semiconductors and can thus be used as switches. Nanoscale FETs attempt to scale this down by contacting a nanostructure with metal electrodes and modulating the carrier density in the channel via a gate voltage. To retain th e switching action in nanoscale FETs, currents which flow in them  must be dissipationless .So a new nanostructures are to be developed  with superconducting materials.eg; carbon nanotubes, n-type InAs nanowires, Ge/Si core/shell nanowires heterostructures, and graphene.

 

This  nanostructure acts as a Josephson junction, and thus a super current is found to flow through it. The geometry is similar to conventional FET geometries: the nanostructure bridges two conductive electrodes (a superconducting metal such as Al) which act as a source and a drain when a suitable voltage is applied across them.The electrodes can be deposited  by using optical or electron-beam lithography and microfabrication/etching techniques coupled with metal evaporation techniques. The nanostructure then acts as a conduction channel that can be tuned via the electric field effect of a highly doped Si back gate separated using several hundred nm of SiO2 dielectric .

 

The transport of electric current in a conductor is associated with the displacement of electrons: Collisions between these electrons and the crystal ions cause resistance and release heat. In superconductors  electrons exits in the form of  pairs,known as cooperpairs ,below the superconducting transition temperature, they allow themselves to synchronize their motion with the ions, and all occupy the same quantum state. Electrons in their normal state can be as free particles  and undergo collisions with each other, where as  in superconducting state electon pair are coupled with each other and move in the same direction without colliding.each other.

 The electron has a charge, but like a tiny magnet, it also has a magnetic moment called spin. In a singlet superconductor, the electron pairs are formed by electrons of opposite spin, which cancels the pair’s magnetic moment. But when the material is placed in a strong magnetic field, the spins are forced to orient themselves along the field, as the field acts on each spin individually. This breaks the pairs and destroys superconductivity.

 

The magnetic fields inside a magnetically ordered material tends to act in the same manner and thus that superconductivity and magnetism tend to avoid each other.But

when a single crystal of CeCoIn5  (a metal compound consisting of cerium, cobalt and indium)  is cooled  to a temperature of minus 273.1 degrees, close to absolute zero,it is observed  that magnetism and superconductivity coexist and disappear at the same time when they heat the sample or increase the magnetic field.This discovery is extraordinary, since magnetic order exists exclusively when this sample is in the superconducting state. In this unique case, magnetism and superconductivity do not compete with each other. Instead, superconductivity generates magnetic order.Thus superconductivity is a condition required to establish this magnetic order. It is observed that magnetic field exits in superconductors  in the form of tiny magnetic dots,which  actually enhance the

superconductivity instead of destroying it.

 

Mechanism  of Superconducting

According to the Bardeen-Cooper-Schreiffer theory of superconductivity, electrons with opposite spins form pairs that can move through a material without resistance. A magnetic field can destroy superconductivity in two ways:.by breaking up the electron pair, or by trying to make both of the electron spins point in the same direction.

 

These effects also limit how much current can flow through the superconductor because of the disruptive effect of the magnetic field produced by the current itself.

Until now, only a few compounds remained superconducting under the influence of an applied magnetic field. Moreover, the number of materials in which an applied field could actually induce superconductivity – by the so-called magnetic field induced superconductivity effect – were very few.

 

Lange and co-workers placed a layer of cobalt-palladium ferromagnetic dots, each 800 nanometres in diameter and separated by 1.5 micrometres, on top of a superconducting thin film made of lead. Each dot produces a stray magnetic field that destroys the superconductivity in the thin film. The researchers then applied an external magnetic field, which enhanced the destructive effect of the dot’s magnetic field in the area directly beneath the dots and, to compensate, reduced it everywhere else in the film. The overall effect was an increase in the current carried by the superconductor.

 

This new ‘field compensation effect’ is not restricted to specific superconductors, the researchers say, so magnetic field induced superconductivity could be achieved in any superconducting thin film. The team believes that using handouts and nanopillars, which have larger stray fields, could allow superconducting materials to remain in higher magnetic fields. The nano-dot array could also be used to design logical devices for use in quantum computers.

 

The Superconducting materials in which current flows without resistance, have tantalizing applications. But even the highest-temperature superconductors require extreme cooling before the effect kicks in, so researchers want to know when and how superconductivity comes about in order to coax it into existence at room temperature.

 

Now a team has shown that, in a copper-based superconductor, tiny areas of weak superconductivity hold up at higher temperatures when surrounded by regions of strong superconductivity.

Researchers says that the Superconducting and normal currents can leak back and forth between adjacent layers of superconducting material and metal. In copper-based ceramic superconductors, made up of many different elements, superconductivity varies within nanometers depending on which atoms are nearby. These tiny regions can influence each other in much the same way that thin layers of metal and superconductor interact.

 

The researchers  of Princeton University, Brookhaven National Laboratory, and the Central Research Institute of Electric Power Industry in Japan has used Scanning Tunneling Microscopy to investigate for the first time how this happens on the nanoscale. They observed that when the superconducting  material is heated , they observed  that superconductivity died out at different temperatures in regions just a few nanometers apart. The Superconductivity just  not  depends on the characteristics of the local region, but also on what was going on nearby.  Regions of stronger superconductivity seemed to help regions of weaker superconductivity ,at higher temperatures.

Researchers might exploit this interplay by micromanaging a superconductor’s structure, so that regions of strong superconductivity have the maximum benefit to weak regions, potentially resulting in a new material that’s superconducting at a higher overall temperature than is possible with randomly arranged ceramic superconductors.

Magnetic impurities destroy superconductivity in conventional low-temperature superconductors, whereas high-Tc superconductors may depend on some kind of magnetic mechanism. Davis and his colleagues to investigate this phenomenon directly at the atomic scale in a superconductor for bismuth strontium calcium copper oxide to determine the influence of individual impurity atoms on electronic structure in their immediate neighborhoods.

 

Superconductivity is the flow of charged particles through a material without resistance, which happens when electrons form so-called Cooper pairs. Cooper pairs form below the superconducting transition temperature (Tc), which is only a few degrees above absolute zero in conventional superconductors, as cold as liquid helium or colder. Phonon quantized vibrations of the materials crystal lattice, helps to create regions of positive charge between the two electrons, “holes” which overcome the mutual repulsion of the electron’s negative charges.

With each Cooper pair there is another kind of pair, formed by each electron and its accompanying hole. These “quasiparticles” are fictitious representations of real particle systems, including the quantum states by which they are identified, but they make computation manageable in a way impossible for complete quantum solutions.

The magnetism persist in superconductor, because Cooper pairs one electron’s spin points ‘up’ and the other’s points ‘down,’ which gives rise to oppositely oriented magnetic moments.”

If an external magnetic field is applied to non superconducting systems, electrons of similar energy are separated by their spins. This splitting doesn’t affect superconductors, because “magnetic fields cannot penetrate the surface region of superconductors.” Where as in a conventional superconducting material the magnetic impurities will destroy the magnetic superconductivity because the Cooper pairs are split apart in the vicinity of each magnetic atom, which in conventional superconductors destroys their superconductivity.”

This is not so for high-Tc superconductors, whose transition temperatures are warmer than liquid nitrogen. “Nickel atoms are magnetic, but nickel impurities have a weak effect on superconductivity in high-Tc superconductors eg: for bismuth strontium calcium copper oxide. Oddly, zinc impurities disrupt it, and zinc atoms are non-magnetic.”

Part of the explanation lies in the electronic states characteristic of high-Tc superconductors. All the highest-Tc superconductors found so far are copper oxide ceramics having the crystal structure of the mineral perovskite, with planes of copper and oxygen atoms (where superconductivity is thought to occur) interlayered with planes of other atoms.

The electronic states of Cooper pairs in high-Tc superconductors are markedly different from those in conventional ones: the two electrons revolve around each other much faster and farther apart, as do their associated quasiparticles. These wider orbits are analogous to the higher-energy d orbitals of electrons around an atom, and high-Tc superconductors are often called d-wave superconductors.

Moreover, the researchers discovered two peaks in energy near each nickel atom, corresponding to the opposing up and down spins of the quasiparticle pairs.

“This shows that a nickel atom retains its overall magnetic moment in the superconducting state and doesn’t disturb that state. Also it maintains the magnetic properties of the cuprate perovskite system.”

If this system is doped with zinc impurities, destroys the superconductivity of this systems — each zinc atom destroying superconductivity within a radius of 1.5 nanometers, possibly because zinc atoms form nonmagnetic voids — this is good evidence that high-Tc superconductivity depends on uninterrupted magnetic pathways to aid the flow of charge. Now it is possible to investigate microscopic organization of high-Tc superconductors on an atom by atom basis.

This investigation leads to measure the quantum spin states of individual atoms which opens the larger vistas of possibility, including a potential mechanism for getting information into and out of the would-be superfast quantum computers of the future.

The use of superconducting films in the Meissner state reduces the level of noise in micro-and nanochips. Superconducting quantum computing is a promising implementation of quantum information that involves nanofabricated superconducting electrodes coupled through Josephson junctions. As in a superconducting electrode, the phase and the charge are conjugate variables, there exists three families of superconducting qubits, depending if the charge, the phase or neither of the two are good quantum numbers. This refers respectively to charge qubits, flux qubits, and hybrid qubits.

Superconducting qubit

Superconducting technologies have the unique potential for realizing compact solid-state devices with controllable macroscopic quantum properties and long coherence time. They represent the most realistic approach for a technology of quantum computers. In superconductors, all electrons are condensed in the same macroscopic quantum state, separated by a gap from the many quasi-particle states. Superconductors can be weakly coupled with Josephson tunnel junctions. The current through a Josephson junction depends upon the phase differences between the superconductors which act as non-commuting conjugate quantum variables to the charges of isolated islands. That makes it possible to construct qubits using superconductors (SQUBIT).

So far, superconducting electronics has not been able to compete with Si- and GaAs-technology in the field of computers, not even for special supercomputers. However, in the emerging field of Quantum Computing the situation is completely different. Now “quantum coherence” is the key issue and superconductivity has great advantages due to its built-in principle of “macroscopic quantum coherence”. An important feature of superconducting junctions is a possibility to reach long decoherence times. The main reason for that is a weak sensitivity of properly designed SQBITs to external electric fields produced by charge fluctuations.

REFERENCES

Y. Nakamura, Yu. A. Pashkin, and J. S. Tsai. Coherent control of macroscopic quantum states in a single-Cooper-pair box. Nature 398, 786 (1999).
Yu. Makhlin, G. Schön, and A. Shnirman. Quantum-state engineering with Josephson-junction devices. Rev. Mod. Phys. 73, 357-400 (2001).
D. Vion et al.. Manipulating the quantum state of an electrical circuit. Science 296,

 

Signor Marconi’s Magic Box: The Most Remarkable Invention Of The 19th Century & The Amateur Inventor Whose Genius Sparked A Revolution

• ISBN13: 9780306813788
• Condition: USED – VERY GOOD
• Notes:

Product Description
The world at the turn of the twentieth century was in the throes of “Marconi-mania”-brought on by an incredible invention that no one could quite explain, and by a dapper and eccentric figure (who would one day win the newly minted Nobel Prize) at the center of it all. At a time when the telephone, telegraph, and electricity made the whole world wonder just what science would think of next, the startling answer had come in 1896 in the form of two mysterious wooden boxes containing a device Marconi had rigged up to transmit messages “through the ether.” It was the birth of the radio, and no scientist in Europe or America, not even Marconi himself, could at first explain how it worked…it just did.

Here is a rich portrait of the man and his era-a captivating tale of British blowhards, American con artists, and Marconi himself-a character par excellence, who eventually winds up a virtual prisoner of his worldwide fame and fortune.

BUY FROM AMAZON–>> Signor Marconi’s Magic Box: The Most Remarkable Invention Of The 19th Century & The Amateur Inventor Whose Genius Sparked A Revolution

Germany – the World’s Most Experienced Market Economies

Germany as an economic hub
Germany is one of the most highly developed industrial nations in the world and, after the USA and Japan has the world’s third largest national economy. With a population of 82.3 million Germany is also the largest and most important market in the European Union (EU). In 2007, Germany’s gross domestic product (GDP) totaled EUR 2.42 trillion, which translates into per-capita GDP of EUR 29,455. With an Export volume of EUR 969 billion or one third of GDP in 2007, Germany is the biggest exporter of goods worldwide, and as such is considered to be the “export world champion”, more of a global player than almost any other country and more strongly linked to the global economy than many other countries.

Most recently, the German economy has seen a robust upturn, growing 2.5 percent in 2007. The increase in corporate investments was especially pronounced at 8.4 percent. The economic growth, stimulated by factors both inside and outside Germany, sparked a reduction in the number of registered unemployed. Economic policy has improved the overall conditions and companies have sharpened their competitive edge. Thus, ancillary wage costs have been reduced, the labor market made more flexible and red tape slashed.

An attractive location for foreign investments
Germany is one of the most attractive countries world-wide for International investors. On an international country comparison, Germany does especially well as regards R&D, skill levels and logistics. Moreover, it enjoys a central geographical position, offers strong infrastructure, legal certainty, and the right workforce. The labor force’s high level of qualifications is seen as an important plus point. Around 80 percent of employees have undergone formal training and only 20 percent hold the degree from a higher education institutes or university. The “dual system” for vocational training provides the bedrock here, combining on-the-job and college training, a policy which results in the well-known high standard of education.

Technology leader in many sectors
Germany is one of the leading nations regarding numerous technologies of the future that have exceptional growth rates. These include bio-technology, nano-technology, IT and the numerous high-tech divisions in individual sectors (aviation and aerospace, electrical engineering, logistics). Companies specializing in environmental technology (wind energy, photovoltaic power and biomass generation) have emerged as front runners. Today, Information and communications technology follows car-making and electronics engineering as the third largest economy’s sector. As per to genetic engineering, Germany is second to the United States worldwide and already has cutting edge in numerous fields of nanotechnology.

The key industrial sectors
The key industrial sectors are car-making, electronics, mechanical engineering and chemicals. As is the case in all western industrial nations, for several years now German industry has been in the midst of structural transformation. Some traditional industries (steel, textiles) have in partly shrunk considerably in recent years, with target markets now elsewhere and strong pressure from lowwage countries, or, as in the case of the pharmaceuticals industry, through M&As have come under foreign ownership.

Successful: Germany in the global economy
Given its high level of exports, Germany is interested in open markets. The most important trading partners are France, the USA and Great Britain. In 2006, goods and services worth EUR 85 billion were exported to France, EUR 78 billion to the USA and EUR 65 billion to Great Britain. In addition to trade with the original European Union member states, since the EU’s expansion eastwards (2004 and 2007) there has been a pronounced increase in trade with the east European EU member states. In total, a good ten percent of all exports go to these countries. The importance of trade and economic relations with emerging nations in Asia such as China and India is growing continually.

Economic system: Performance and social balance
Germany is a Social market economy. This is other strong reason why Germany enjoys a high degree of social harmony, something reflected in the fact that labor disputes are so rare here. On average between 1996 and 2005 the work force went on strike for on just 2.4 days per 1,000 employees and thus less than even Switzerland, which saw 3.1 days of strikes. The social partnership of trade unions and employer associations is enshrined in the institutionalized settlement of conflicts as outlined in the collective labor law. The Basic Law guarantees the social partners independence in negotiating wages, and they accordingly have the right themselves to select the working conditions.

All the latest information about Germany economy is available at German Information Centre. So if you are interested in knowing about Germany economy please visit at German Information Centre.

Next Page »