Thermodynamic magic enables cooling without energy consumption

Physicists at the University of Zurich have developed an amazingly simple device that allows heat to flow temporarily from a cold to a warm object without an external power supply. Intriguingly, the process initially appears ...

Successful tests of a cooler way to transport electricity

Like a metal python, the huge pipe snaking through a CERN high-tech hall is actually a new electrical transmission line. This superconducting line is the first of its kind and allows vast quantities of electrical current ...

Triplet superconductivity demonstrated under high pressure

Researchers in France and Japan have demonstrated a theoretical type of unconventional superconductivity in a uranium-based material, according to a study published in the journal Physical Review Letters.

Improving quantum computers

For decades, experts have predicted that quantum computers will someday perform difficult tasks, such as simulating complex chemical systems, that can't be done by conventional computers. But so far, these machines haven't ...

The mechanism of high-temperature superconductivity is found

Russian physicist Viktor Lakhno from Keldysh Institute of Applied Mathematics, RAS considers symmetrical bipolarons as a basis of high-temperature superconductivity. The theory explains recent experiments in which a superconductivity ...

In a new quantum simulator, light behaves like a magnet

Physicists at EPFL propose a new "quantum simulator": a laser-based device that can be used to study a wide range of quantum systems. Studying it, the researchers have found that photons can behave like magnetic dipoles at ...

Physicists reverse time using quantum computer

Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated ...

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Superconductivity

Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect). It was discovered by Heike Kamerlingh Onnes in 1911. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It cannot be understood simply as the idealization of "perfect conductivity" in classical physics.

The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit. Even near absolute zero a real sample of copper shows a non-zero resistance. The resistance of a superconductor, despite these imperfections, drops abruptly to zero when the material is cooled below its "critical temperature". An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source.

Superconductivity occurs in a wide variety of materials, including simple elements like tin and aluminium, various metallic alloys and some heavily-doped semiconductors. Superconductivity does not occur in noble metals like gold and silver, nor in pure samples of ferromagnetic metals.

In 1986 the discovery of a family of cuprate-perovskite ceramic materials known as high-temperature superconductors, with critical temperatures in excess of 90 kelvin, spurred renewed interest and research in superconductivity for several reasons. As a topic of pure research, these materials represented a new phenomenon not explained by the current theory. In addition, because the superconducting state persists up to more manageable temperatures, past the economically-important boiling point of liquid nitrogen (77 kelvin), more commercial applications are feasible, especially if materials with even higher critical temperatures could be discovered.

See also the history of superconductivity.

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