Most accurate relative gravimeters are superconducting gravimeters, and these are sensitive to one thousandth of one billionth of the Earth surface gravity.

The most accurate relative gravimeters are superconducting gravimeters, which operate by suspending a liquid helium cooled diamagnetic superconducting niobium sphere in an extremely stable magnetic field ; the current required to generate the magnetic field that suspends the niobium sphere is proportional to the strength of the Earth's gravitational field.

Furthermore, it describes how the density of states is changed on entering the superconducting state, where there are no electronic states any more at the Fermi energy.

The most familiar condensed phases are solids and liquids, while more exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on atomic lattices, and the Bose-Einstein condensate found in cold atomic systems.

This is the origin of superconductivity and the superfluidity of helium-3: in superconducting materials, electrons interact through the exchange of phonons, forming Cooper pairs, while in helium-3, Cooper pairs are formed via spin fluctuations.

These superconducting alloys, also containing titanium and tin, are widely used in the superconducting magnets of MRI scanners.

Superconductors are also able to maintain a current with no applied voltage whatsoever, a property exploited in superconducting electromagnets such as those found in MRI machines.

This structure causes a large anisotropy in normal conducting and superconducting properties, since electrical currents are carried by holes induced in the oxygen sites of the CuO < sub > 2 </ sub > sheets.

All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger ’ s cat state.

There are several reasons for using superconducting magnetic energy storage instead of other energy storage methods.

As with other superconducting applications, cryogenics are a necessity.

Most of the superconducting materials found to date are relatively delicate ceramics, making it difficult to use established techniques to draw extended lengths of superconducting wire.

These still pose problems for superconducting applications but are improving over time.

Such tungsten alloys are sometimes used in low-temperature superconducting circuits.

The tungsten metal sensors are held at the critical temperature so they are in the superconducting state.

The thin barriers on each path are Josephson junctions, which together separate the two superconducting regions.

The traditional superconducting materials for SQUIDs are pure niobium or a lead alloy with 10 % gold or indium, as pure lead is unstable when its temperature is repeatedly changed.

All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger ’ s cat state.

Examples of vector magnetometers are fluxgates, superconducting quantum interference devices ( SQUIDs ), and the atomic SERF magnetometer.

Superconducting magnets are limited by the field strength at which the winding material ceases to be superconducting.

However, several iron-based compounds ( the iron pnictides ) are now known to be superconducting at high temperatures.

* The BCS theory reproduces the isotope effect, which is the experimental observation that for a given superconducting material, the critical temperature is inversely proportional to the mass of the isotope used in the material.

Helium is used in cryogenics ( its largest single use, absorbing about a quarter of production ), particularly in the cooling of superconducting magnets, with the main commercial application being in MRI scanners.

Niobium is used in various superconducting materials.

Due to the energy requirements of refrigeration and the high cost of superconducting wire, SMES is currently used for short duration energy storage.

A cryogenic system is used to prevent heat loss from the superconducting magnets.

A SQUID ( for superconducting quantum interference device ) is a very sensitive magnetometer used to measure extremely subtle magnetic fields, based on superconducting loops containing Josephson junctions.

* powerful superconducting electromagnets used in maglev trains, Magnetic Resonance Imaging ( MRI ) and Nuclear magnetic resonance ( NMR ) machines, magnetic confinement fusion reactors ( e. g. tokamaks ), and the beam-steering and focusing magnets used in particle accelerators

The most commonly used conventional superconductor in applications is a niobium-titanium alloy-this is a type-II superconductor with a superconducting critical temperature of 11 K. The highest critical temperature so far achieved in a conventional superconductor was 39 K (- 234 ° C ) in magnesium diboride.

To make this possible HERA used mainly superconducting magnets, which was also a world first.

When a magnetic field higher than the ferromagnetic limit of 1. 6 T is needed, superconducting electromagnets can be used.

At present, however, the superconducting magnets that are used in the process have to themselves be cooled down to the temperature of liquid nitrogen, or with even colder, and relatively expensive, liquid helium.

* SQUID ( superconducting quantum interference device ), a superconducting loop used to make sensitive measurements of magnetic fields

The quality factor of atomic clocks, superconducting RF cavities used in accelerators, and some high-Q lasers can reach as high as 10 < sup > 11 </ sup > and higher.

In more recent decades, some liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use in superconducting magnets such as those used in magnetic resonance imaging ( MRI ), nuclear magnetic resonance ( NMR ), and experiments in physics.

The strength and magnetic field homogeneity on neodymium magnets has also opened new applications in the medical field with the introduction of open magnetic resonance imaging ( MRI ) scanners used to image the body in radiology departments as an alternative to superconducting magnets that use a coil of superconducting wire to produce the magnetic field.

He used Ginzburg-Landau theory to explain experiments on superconducting alloys and thin films.

Experiments have demonstrated that currents in superconducting coils can persist for years without any measurable degradation.

If the material superconducts in the absence of a field, then the superconducting phase free energy is lower than that of the normal phase and so for some finite value of the magnetic field ( proportional to the square root of the difference of the free energies at zero magnetic field ) the two free energies will be equal and a phase transition to the normal phase will occur.

The first equation follows from the Newton's second law for superconducting electrons.

Such fixed points, for example, triple points and superconducting transitions, occur reproducibly at the same temperature.

These include, for example, tests of number-phase uncertainty relations in superconducting or quantum optics systems.

The development of superconductors with transition temperatures higher than the boiling point of liquid nitrogen has made the concept of superconducting power lines commercially feasible, at least for high-load applications.

The GP-B gyro consists of a nearly-perfect spherical rotating mass made of fused quartz, which provides a dielectric support for a thin layer of niobium superconducting material.

Called the SRC, for Superconducting Ring Cyclotron, it has 6 separated superconducting sectors, and is 19m in diameter and 8m high.

The experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconducting state.

FLASH ( Free-electron-LASer in Hamburg ) is a superconducting linear accelerator with a free electron laser for radiation in the vacuum-ultraviolet and soft X-ray range of the spectrum.

This is the case for both semiconducting and superconducting materials at low temperature.

The old copper magnets accelerator was shut down on August 15, 1977 for superconducting magnets to be mounted ' pickaback ' on the main ring magnets.

* Argonne Tandem Linac Accelerator System ( ATLAS ) – ATLAS is the world's first superconducting particle accelerator for heavy ions at energies in the vicinity of the Coulomb barrier.

Arrays of SQUIDs ( superconducting quantum interference devices ) are currently the most common magnetometer, and SERF being investigated for future machines.

Another accurate method for measuring the elementary charge is by inferring it from measurements of two effects in quantum mechanics: The Josephson effect, voltage oscillations that arise in certain superconducting structures ; and the quantum Hall effect, a quantum effect of electrons at low temperatures, strong magnetic fields, and confinement into two dimensions.

2. a crytron switch depends on the effect of inducing persistent current in a closed superconducting circuit for eg. ring