Shrinking qubits for quantum computing with atom-thin materials

For quantum computers to surpass their classical counterparts in speed and capacity, their qubits—which are superconducting circuits that can exist in an infinite combination of binary states—need to be on the same wavelength. ...

Thermoelectric crystal conductivity reaches a new high

Just as a voltage difference can generate electric current, a temperature difference can generate a current flow in thermoelectric materials governed by its "Peltier conductivity" (P). Now, researchers from Japan demonstrate ...

New material could be two superconductors in one

MIT physicists and colleagues have demonstrated an exotic form of superconductivity in a new material the team synthesized only about a year ago. Although predicted in the 1960s, until now this type of superconductivity has ...

A superconducting silicon-photonic chip for quantum communication

Integrated quantum photonics (IQP) is a promising platform for realizing scalable and practical quantum information processing. Up to now, most of the demonstrations with IQP focus on improving the stability, quality, and ...

New tricks for finding better superconductive materials

Even after more than 30 years of research, high-temperature superconductivity is still one of the great unsolved mysteries of materials physics. The exact mechanism that causes certain materials to still conduct electric ...

Unmasking the magic of superconductivity in twisted graphene

The discovery in 2018 of superconductivity in two single-atom-thick layers of graphene stacked at a precise angle of 1.1 degrees (called 'magic'-angle twisted bilayer graphene) came as a big surprise to the scientific community. ...

'Magnet training' at the LHC

When the Large Hadron Collider (LHC) begins Run 3 next year, operators aim to increase the energy of the proton beams to an unprecedented 6.8 TeV. This means the thousands of superconducting magnets, whose fields direct the ...

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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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