Quantum fluid

Rare-gas clusters can be produced easily using supersonic expansion. They are attractive to study theoretically because the interaction potentials are relatively simple and dominated by the van der Waals interactions. The Lennard-Jones pair potential describes the stmctures of the rare-gas clusters well and predicts magic clusters with icosahedral stmctures [139, 140]. The first five icosahedral clusters occur at 13, 55, 147, 309 and 561 atoms and are observed in experiments of Ar, Kr and Xe clusters [1411. Small helium clusters are difficult to produce because of the extremely weak interactions between helium atoms. Due to the large zero-point energy, bulk helium is a quantum fluid and does not solidify under standard pressure. Large helium clusters, which are liquid-like, have been produced and studied by Toennies and coworkers [142]. Recent experiments have provided evidence of... 

By using the relationship between the fluid current and its veloeity field, J = Pv, a quantum fluid velocity field of... 

This proves that the pseudoparticles in the quantum fluid obey classical mechanics in the classical limit. 

Quantum efficiencies Quantum efficiency Quantum electronics Quantum fluids Quantum mechanics Quantum size effect Quantumwell... 

Quantum Fluids. Light compounds which exhibit behavior resulting from quantum effects, eg, hydrogen, helium, and neon, are called quantum fluids. 

S. Dietrieh. Fluids in eontaet with struetured substrates. In C. Caeeamo ed. Proceedings of the NATO-ASI New approaches to old and new problems in licpud state theory—inhomogeneities and phase separation in siniple, complex, and quantum fluids." Dordreeht Kluwer, 1999. 

H. Wiechert. In A. G. F. Wyatt, H. J. Lauter, eds. Excitations in Two-Dimensional and Three-Dimensional Quantum Fluids. New York Plenum Press, 1991. 

Quantum Fluid Dynamics Time-Dependence of Single-Particle Density.52... 

The three main approaches based on the single-particle density are the density functional theory (DFT), quantum fluid dynamics (QFD), and studying the properties of a system through local quantities in 3D space. In this chapter, we present simple discussions on certain conceptual and methodological aspects of the single-particle density for details, the reader may consult the references listed at the end of this chapter. 

QUANTUM FLUID DYNAMICS TIME-DEPENDENCE OF SINGLE-PARTICLE DENSITY [2,3,14,15]... 

First, there are constraints among the material quantities, which are rather straightforward for ideal quantum fluids. In case of interacting matter one can recall the self-consistent description of the interacting fermions in the 4 dimensional analogy [13], Second, the particle number density in the center, n(r = 0), is a free initial condition, as it was in the 4 dimensional case. Instead of density, we may use energy density, e(r = 0) = 0 as well. 

Helium (the simplest possible elemental species) remains a liquid at T = 0 (unless the pressure is increased above about 20 atm). Bizarre quantum fluid effects and nonzero entropies are exhibited by both 3He and 4He in the T —> 0 limit. 

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. 

An overview on the vast experimental and theoretical work on BEC recently we refer to the BEC-homepage [37]. Most experimental BEC research is carried out with alkali metal atoms and the main topics are to characterize the quantum fluid. 

S. A. Bonev, E. Schwegler, T. Ogitsu, and G. GaUi (2004) A quantum fluid of metallic hydrogen suggested by first-principles calculations. Nature 431, p. 669... 

Note Liquid helium has unique thermodynamic properties too complex to be adequately described here. Liquid He I has refr index 1.026,dO.l 25, and is called a quantum fluid because it exhibits atomic properties on a macroscopic scale. Its bp is near absolute zero and viscosity is 25 micropoises (water = 10,000). He II, formed on cooling He I below its transition point, has the unusual property of superfluidity, extremely high thermal conductivity, and viscosity approaching zero. 

The global Hamiltonian for a Bose quantum fluid written in the hydrodynamic form [19] is... 

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