Fermionic condensate

Other States of Matter Research and prepare an oral report about one of the following topics plasma, superfluids, fermionic condensate, or Bose-Einstein condensate. Share your report with your classmates and prepare a visual aid that can be used to explain your topic. 

Ceperley D M 1996 Path integral Monte Carlo for fermions Monte Carlo and Molecular Dynamics of Condensed Matter Systems vol 49, ed K Binder and E G Ciccotti (Bologna Italian Physical Society) pp 443-82... 

Liquid Helium-4. Quantum mechanics defines two fundamentally different types of particles bosons, which have no unpaired quantum spins, and fermions, which do have unpaired spins. Bosons are governed by Bose-Einstein statistics which, at sufficiently low temperatures, allow the particles to coUect into a low energy quantum level, the so-called Bose-Einstein condensation. Fermions, which include electrons, protons, and neutrons, are governed by Fermi-DHac statistics which forbid any two particles to occupy exactly the same quantum state and thus forbid any analogue of Bose-Einstein condensation. Atoms may be thought of as assembHes of fermions only, but can behave as either fermions or bosons. If the total number of electrons, protons, and neutrons is odd, the atom is a fermion if it is even, the atom is a boson. 

It is important to stress that use of the generalised Bogoliubov transformatin provides an elegant physical interpretation of the Casimir effect as a consequence of the condensation in the vacuum of the fermion or the boson field. The method can be extended to other geometries such as spherical or cylindrical. 

Finally, also in the laboratory the study of the interaction of cavities inside a uniform fermionic background is of importance (Bulgac and Wirzba., 2001). Examples are C6o buckyballs immersed in liquid mercury. The liquid metal itself serves only as free-moving shapeable neutral background which provides the Fermi gas environment by its conductance electrons, in which the buckyballs drill the voids. Another example would be buckyballs in liquid 3He as Fermi gas. Finally, in the future, boson condensate cavities immersed in dilute atomic Fermi condensates could serve as further system with which the effective interactions of cavities inside a Fermi gas can be studied in the lab. 

One of the most amazing phenomena in quantum many-particle systems is the formation of quantum condensates. Of particular interest are strongly coupled fermion systems where bound states arise. In the low-density limit, where even-number fermionic bound states can be considered as bosons, Bose-Einstein condensation is expected to occur at low temperatures. The solution of Eq. (6) with = 2/j, gives the onset of pairing, the solution of Eq. (7) with EinP = 4/i the onset of quartetting in (symmetric) nuclear matter. At present, condensates are investigated in systems where the cross-over from Bardeen-Cooper-Schrieffer (BCS) pairing to Bose-Einstein condensation (BEC) can be observed, see [11,12], In these papers, a two-particle state is treated in an uncorrelated medium. Some attempts have been made to include the interaction between correlated states, see [7,13]. 

We recall that we can saturate the t Hooft anomaly conditions either with massless fermionic degrees of freedom or with gapless bosonic excitations. However in absence of Lorentz covariance the bosonic excitations are not restricted to be fluctuations related to scalar condensates but may be associated, for example, to vector condensates [51]. 

Due to Heisenberg s uncertainty and Pauli s exclusion principles, the properties of a multifermionic system correspond to fermions being grouped into shells and subshells. The shell structure of the one-particle energy spectrum generates so-called shell effects, at different hierarchical levels (nuclei, atoms, molecules, condensed matter) [1-3]. 

Figure 7.4 illustrates the phase diagram of the 4He isotope in the low-temperature condensation region. The thermodynamic properties of 4He are fundamentally distinct from those of the trace isotope 3He, and the two isotopes spontaneously phase-separate near IK. Both isotopes exhibit the spectacular phenomenon of superfluidity, the near-vanishing of viscosity and frictional resistance to flow. The strong dependence on fermionic (3He) or bosonic (4He) character and bizarre hydrodynamic properties are manifestations of the quantum fluid nature of both species. 3He is not discussed further here. 

This difference between fermions and bosons is reflected in how they occupy a set of states, especially as a function of temperature. Consider the system shown in Figure E.10. At zero temperature (T = 0), the bosons will try to occupy the lowest energy state (a Bose-Einstein condensate) while for the fermions the occupancy will be one per quantum state. At high temperatures the distributions are similar and approach the Maxwell Boltzman distribution. 

BOSE-EINSTEIN CONDENSATION IN A BOSON-FERMION MODEL OF CUPRATES... 

Key words Superconductivity cuprates boson-fermion model Bose-Einstein condensation. 

Bose-Einstein Condensation in a Boson-Fermion Model of Cuprates 135 T.A. Mamedov, and M. de Llano... 

PROBLEM 5.1.3. If fermions, such as the neutrons (7=1/2) that make a hot neutron star, merge to form a massive Bose particle (cold black hole), then Bose-Einstein condensation occurs, the whole star loses energy massively, and a new minimum energy state is reached (cold black hole) (see also Problem 2.12.4). 

An alternative approach is the Slave Boson approximation [21] where the Fermionic operators are defined as the product of Boson and spin operators. There is a constraint with the number of Fermions, n /, and number of Bosons, n n f - - m, = 1. The spin part is treated with a RVB spin model and the charge as a Bose-Einstein condensation problem. These leads to a fractionalization of charges (holons) and spin (spinons), where uncondensed holons exist above the SC domain. The temperature crossover of the spinon pairing and the holon condensation, as a function of doping, is identified as peak in the SC domain. 

D. M. Ceperley (1996) Path integral Monte Carlo methods for fermions. In Monte Carlo and Molecular Dynamics of Condensed Matter Systems, ed. by K. Binder and G. Ciccotti, Editrice Compositori, Bologna, Italy... 

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