A fermionic condensate is a superfluid phase formed by fermionic particles at low temperatures. It is closely related to the Bose-Einstein condensate, a superfluid phase formed by bosonic atoms under similar conditions. Unlike the Bose-Einstein condensates, fermionic condensates are formed using fermions instead of bosons. The earliest recognized fermionic condensate described the state of electrons in a superconductor; the physics of other examples including recent work with fermionic atoms is analogous. The first atomic fermionic condensate was created by Deborah S. Jin in 2003. A chiral condensate is an example of a fermionic condensate that appears in theories of massless fermions with chiral symmetry breaking. Helium II will creep along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... For other uses, see Temperature (disambiguation). ... A Bose–Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero (0 kelvins or -273. ... In particle physics, bosons, named after Satyendra Nath Bose, are particles having integer spin. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... For other uses, see Electron (disambiguation). ... A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... For other uses, see Atom (disambiguation). ... Deborah S. Jin (born 1968) is a physicist with the NIST; Assistant Professor Adjoint, Department of Physics at the University of Colorado; a fellow of the Joint Institute for Laboratory Astrophysics (JILA), a National Institute of Standards and Technology joint laboratory with the University of Colorado and leader of the... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... A phenomenon is said to be chiral if it is not identical to its mirror image (see Chirality (mathematics)). The spin of a particle may be used to define a handedness for that particle. ...

Background

Superfluidity

Fermionic condensates are a type of superfluid. As the name suggests, a superfluid possesses fluid properties similar to those possessed by ordinary liquids and gases, such as the lack of a definite shape and the ability to flow in response to applied forces. However, superfluids possess some properties that do not appear in ordinary matter. For instance, they can flow at low velocities without dissipating any energy—i.e. zero viscosity. At higher velocities, energy is dissipated by the formation of quantized vortices, which act as "holes" in the medium where superfluidity breaks down. A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... For other uses, see Gas (disambiguation). ... For other uses, see Viscosity (disambiguation). ... This page is a candidate for speedy deletion. ...

Superfluidity was originally discovered in liquid helium-4, in 1938, by Pyotr Kapitsa, John Allen and Don Misener. Superfluidity in helium-4, which occurs at temperatures below 2.17 kelvins (K), has long been understood to result from Bose condensation, the same mechanism that produces the Bose-Einstein condensates. The primary difference between superfluid helium and a Bose-Einstein condensate is that the former is condensed from a liquid while the latter is condensed from a gas. General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... Year 1938 (MCMXXXVIII) was a common year starting on Saturday (link will take you to calendar). ... Semenov (on the right) and Kapitsa (on the left), portrait by Boris Kustodiev, 1921 Pyotr Leonidovich Kapitsa (Russian Пётр Леонидович Капица) (July 9, 1894 – April 8, 1984) was a Soviet/Russian physicist who discovered superfluidity with some contribution from John F. Allen and Don Misener in 1937. ... John F. Allen (May 5, 1908-April 22, 2001 was a scientist. ... Don Misener was a physicist. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... For other uses, see Gas (disambiguation). ...

Fermionic superfluids

It is far more difficult to produce a fermionic superfluid than a bosonic one, because the Pauli exclusion principle prohibits fermions from occupying the same quantum state. However, there is a well-known mechanism by which a superfluid may be formed from fermions. This is the BCS transition, discovered in 1957 by John Bardeen, Leon Cooper and Robert Schrieffer for describing superconductivity. These authors showed that, below a certain temperature, electrons (which are fermions) can pair up to form bound pairs now known as Cooper pairs. As long as collisions with the ionic lattice of the solid do not supply enough energy to break the Cooper pairs, the electron fluid will be able to flow without dissipation. As a result, it becomes a superfluid. The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. ... A quantum state is any possible state in which a quantum mechanical system can be. ... BCS theory (named for its creators, Bardeen, Cooper, and Schrieffer) successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. ... Year 1957 (MCMLVII) was a common year starting on Tuesday (link displays the 1957 Gregorian calendar). ... John Bardeen (May 23, 1908 – January 30, 1991) was an American physicist and electrical engineer. ... Leon Neil Cooper (born February 28, 1930) is an American physicist and winner of the 1972 Nobel Prize for Physics, along with John Bardeen and John Robert Schrieffer, for his role in developing the BCS theory (named for their initials) of superconductivity. ... John Robert Schrieffer (born May 31, 1931) is an American physicist and winner, with John Bardeen and Leon Neil Cooper, of the 1972 Nobel Prize for Physics for developing the BCS theory (for their initials), the first successful microscopic theory of superconductivity. ... A Cooper pair is the name given to electrons that are bound together in a certain manner first described by Leon Cooper. ...

The BCS theory was phenomenally successful in describing superconductors. Soon after the publication of the BCS paper, several theorists proposed that a similar phenomenon could occur in fluids made up of fermions other than electrons, such as helium-3 atoms. These speculations were confirmed in 1971, when experiments performed by Douglas D. Osheroff showed that helium-3 becomes a superfluid below 0.0025 K. It was soon verified that the superfluidity of helium-3 arises from a BCS-like mechanism. (The theory of superfluid helium-3 is a little more complicated than the BCS theory of superconductivity. These complications arise because helium atoms repel each other much more strongly than electrons, but the basic idea is the same.) Helium-3 is a non-radioactive and light isotope of helium. ... Year 1971 (MCMLXXI) was a common year starting on Friday (link will display full calendar) of the 1971 Gregorian calendar. ... Douglas Dean Osheroff (born August 1, 1945) is a American physicist. ...

Creation of the first fermionic condensates

When Eric Cornell and Carl Wieman produced a Bose-Einstein condensate from rubidium atoms in 1995, there naturally arose the prospect of creating a similar sort of condensate made from fermionic atoms, which would form a superfluid by the BCS mechanism. However, early calculations indicated that the temperature required for producing Cooper pairing in atoms would be too cold to achieve. In 2001, Murray Holland at JILA suggested a way of bypassing this difficulty. He speculated that fermionic atoms could be coaxed into pairing up by subjecting them to a strong magnetic field. Eric Allin Cornell (born December 19, 1961) is a physicist who, along with Carl E. Wieman, was able to synthesize Bose-Einstein condensate in 1995. ... Carl Edwin Wieman (born March 26, 1951) is a Nobel-prize winning American physicist at the University of British Columbia who (with Eric Allin Cornell), in 1995, produced the first true Bose-Einstein condensate. ... General Name, Symbol, Number rubidium, Rb, 37 Chemical series alkali metals Group, Period, Block 1, 5, s Appearance grey white Atomic mass 85. ... For other uses, see Atom (disambiguation). ... Year 1995 (MCMXCV) was a common year starting on Sunday (link will display full 1995 Gregorian calendar). ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... JILA, formerly known as the Joint Institute for Laboratory Astrophysics, is one of the leading physical science research institutes in the United States. ... Magnetic field lines shown by iron filings In physics, the space surrounding moving electric charges, changing electric fields and magnetic dipoles contains a magnetic field. ...

In 2003, working on Holland's suggestion, Deborah Jin at JILA, Rudolf Grimm at the University of Innsbruck, and Wolfgang Ketterle at MIT managed to coax fermionic atoms into forming molecular bosons, which then underwent Bose-Einstein condensation. However, this was not a true fermionic condensate. Later that year, Jin managed to produce a condensate out of fermionic atoms for the first time. The experiment involved 500,000 potassium-40 atoms cooled to a temperature of 5×10⁻⁸ K, subjected to a time-varying magnetic field. The findings were published in the online edition of Physical Review Letters on January 24, 2004. Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... The Leopold-Franzens-Universität, more often simply called University of Innsbruck, is one of the major Austrian universities, offering a broad range of subjects. ... Wolfgang Ketterle (born October 21, 1957, in Heidelberg, Germany) is a German physicist and a professor of physics at the Massachusetts Institute of Technology. ... Mapúa Institute of Technology (MIT, MapúaTech or simply Mapúa) is a private, non-sectarian, Filipino tertiary institute located in Intramuros, Manila. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... Physical Review Letters is one of the most prestigious journals in physics. ... is the 24th day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...

Examples

BCS theory

The BCS theory of superconductivity has a fermion condensate. A pair of electrons in a metal, with opposite spins can form a scalar bound state called a Cooper pair. Then, the bound states themselves form a condensate. Since the Cooper pair has electric charge, this fermion condensate breaks the electromagnetic gauge symmetry of a superconductor, giving rise to the wonderful electromagnetic properties of such states. BCS theory (named for its creators, Bardeen, Cooper, and Schrieffer) successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. ... A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... For other uses, see Electron (disambiguation). ... This article does not cite any references or sources. ... In physics, a scalar is a simple physical quantity that does not depend on direction, and therefore does not depend on the choice of a coordinate system. ... In physics, a bound state is a composite of two or more building blocks (particles or bodies) that behaves as a single object. ... A Cooper pair is the name given to electrons that are bound together in a certain manner first described by Leon Cooper. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... Gauge theories are a class of physical theories based on the idea that symmetry transformations can be performed locally as well as globally. ...

QCD

In Quantum chromodynamics (QCD) the chiral condensate is also called the quark condensate. This property of the QCD vacuum is partly responsible for giving masses to hadrons (along with other condensates like the gluon condensate). Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). ... In Quantum chromodynamics (QCD), the gluon condensate is a non-perturbative property of the QCD vacuum which could be partly responsible for giving masses to certain hadrons. ...

In an approximate version of QCD, which has vanishing quark masses for N quark flavours, there is an exact chiral SU(N)xSU(N) symmetry of the theory. The QCD vacuum breaks this symmetry to SU(N) by forming a quark condensate. The quark condensate is therefore an order parameter of transitions between several phases of quark matter in this limit. The initialism QCD can mean: Quantum chromodynamics Quintessential Player, formerly known as Quintessential CD Quality, Cost, Delivery, A three-letter acronym used in lean manufacturing This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the... Flavour (or flavor) is a quantum number of elementary particles related to their weak interactions. ... The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). ... In physics, a phase transition is the transformation of a thermodynamic system from one phase to another. ... Quark Matter refers to any of a number of phases of matter built out of quarks and gluons. ...

This is very similar to the BCS theory of superconductivity. The Cooper pairs are analogous to the pseudoscalar mesons. However, the vacuum carries no charge. Hence all the gauge symmetries are unbroken. Corrections for the masses of the quarks can be incorporated using chiral perturbation theory. BCS theory (named for its creators, Bardeen, Cooper, and Schrieffer) successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. ... BCS theory successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. ... In mathematics and physics, a pseudoscalar is a quantity that behaves more or less like a scalar, except that it transforms oddly under the action of a discrete group. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... Gauge theories are a class of physical theories based on the idea that symmetry transformations can be performed locally as well as globally. ... The six flavours of quarks and their most likely decay modes. ... Chiral perturbation theory (ChPT) is an effective field theory constructed with a lagrangian consistent with the (approximate) chiral symmetry of quantum chromodynamics (QCD), as well as the other symmetries of parity and charge conjugation. ...

Helium-3 superfluid

A helium-3 atom is a fermion and at very low temperatures, they form two-atom Cooper pairs which are bosonic and condense into a superfluid. These Cooper pairs are substantially larger than the interatomic separation. Helium-3 is a non-radioactive and light isotope of helium. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... Helium II will creep along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. ...

See also

• Superconductivity and the BCS theory.
• The QCD vacuum and the gluon condensate.
• Quark matter, diquark condensate and the pion condensate.
• The top quark condensate and Technicolor models.
• Nambu-Jona-Lasinio model
• Gross-Neveu model
• gaugino condensate

A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... BCS theory (named for its creators, Bardeen, Cooper, and Schrieffer) successfully explains conventional superconductivity, the ability of certain metals at low temperatures to conduct electricity without resistance. ... The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). ... In Quantum chromodynamics (QCD), the gluon condensate is a non-perturbative property of the QCD vacuum which could be partly responsible for giving masses to certain hadrons. ... Quark Matter refers to any of a number of phases of matter built out of quarks and gluons. ... // Overview Color superconductivity is a phenomenon predicted to occur in quark matter if the baryon density is sufficiently high (well above nuclear density) and the temperature is not too high (well below 1012 Kelvin). ... The top quark condensate theory is an alternative to the Standard Model without a scalar Higgs field, or alternatively put, the Higgs field is a composite field. ... Technicolor models are theories beyond the Standard Model (sometimes, but not always, GUTs) which do not have a scalar Higgs field. ... In quantum field theory, the Nambu-Jona-Lasinio model is a theory of interacting Dirac fermions with chiral symmetry. ... The Gross-Neveu model is a quantum field theory model of Dirac fermions interacting via four fermion interactions. ... In particle physics, gaugino condensation is the nonzero vacuum expectation value in some models of a bilinear expression constructed in theories with supersymmetry from the superpartner of a gauge boson called the gaugino. ...

References

• Guenault, Tony (2003). Basic superfluids. Taylor & Francis. ISBN 0-7484-0892-4. 
• University of Colorado (January 28, 2004). NIST/University of Colorado Scientists Create New Form of Matter: A Fermionic Condensate. Press Release.
• Rodgers, Peter & Dumé, Bell (January 28, 2004). Fermionic condensate makes its debut. PhysicWeb.