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- Keyword
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- Bose-Einstein condensation (3)
- Ideal Bose gas (2)
- Permutation cycles (2)
- Boltzmann equation - transport equation - Snider equation - BBGKY hierarchy - virial corrections - molecular fields (1)
- Bose-Einstein condensates - Fock state - Interferometers - NOON state (1)
-
- Dilute solutions (1)
- Fermi fluids (1)
- He-3 normal liquid polarized (1)
- He-3-He-4 mixture liquid (1)
- NMR (1)
- Nanotubes (1)
- Path-integral Monte Carlo (1)
- Path-integral Monte Carlo simulations (1)
- Quantum fluid (1)
- Quantum fluids (1)
- Refrigeration (1)
- Spin polarized He-3 (1)
- Spin-polarized He-3-He-4 mixtures (1)
- Two-dimensional Bose systems (1)
Articles 31 - 45 of 45
Full-Text Articles in Physical Sciences and Mathematics
Theory Of Spin Diffusion Of Dilute, Polarized Fermions For All Temperatures, Jw Jeon, Wj Mullin
Theory Of Spin Diffusion Of Dilute, Polarized Fermions For All Temperatures, Jw Jeon, Wj Mullin
William J. Mullin
We describe the solution of the transport equation over the entire range of temperature from the Boltzmann to fully degenerate regimes for dilute, polarized Fermi systems. Since spin-polarized systems can show unusual quantum effects involving spin rotation in both Boltzmann and degenerate regimes, a solution of the kinetic equation over the whole temperature range is expected to be useful. Our results for the longitudinal spin diffusion coefficient reduce to the known limits in the Boltzmann and degenerate regimes and also to the expected form in the peculiar high-polarization regime in which one spin species is degenerate and the other described …
Theory Of A Polarized Fermi-Liquid In 2 Dimensions - Spin Diffusion, K Miyake, Wj Mullin
Theory Of A Polarized Fermi-Liquid In 2 Dimensions - Spin Diffusion, K Miyake, Wj Mullin
William J. Mullin
The spin diffusion coefficientD of a polarized two-dimensional degenerate Fermi fluid is evaluated as a model of submonolayer3He adsorbed on a flat substrate. The problem is formulated to account fully for Fermi liquid and spin polarization effects. Because in two dimensions, for zero or weak polarization, the only allowed scattering angles are zero and pgr, the transport coefficients become expressible in terms of Landau parameters without approximation. The dependence ofD on polarizationP is given for arbitraryP. For unpolarized and weakly polarized systems, in particular, it is shown thatD –1 simT 2lnT andT 2lnP, respectively. The two-dimensional kinetic equation is found …
Spin Transport In Very Dilute He-3-He-4 At Very High B/T, H Akimoto, Js Xia, Ed Adams, D Candela, Wj Mullin, Ns Sullivan
Spin Transport In Very Dilute He-3-He-4 At Very High B/T, H Akimoto, Js Xia, Ed Adams, D Candela, Wj Mullin, Ns Sullivan
William J. Mullin
We report preliminary results for pulsed-NMR measurements on a very dilute 3 He- 4 He mixture (x 3 =900 ppm) in a 14.74 T field at temperatures down to 3 mK. The aim of the project is to investigate low temperature transverse spin relaxation and possible spin diffusion anisotropy. Spin-echo and T1-type measurements were employed to measure the transverse and longitudinal spin diffusion coefficients. At high temperatures both spin diffusion coefficients are well explained assuming a quasiparticle interaction consistent with previous experiments. Conversely, at low temperatures the measured value of |lambdaohgrtaubottom| is apparently limited to about ten by a poorly-understood …
Spin Diffusion In 2d And 3d Quantum Solids, B Cowan, Wj Mullin, E Nelson
Spin Diffusion In 2d And 3d Quantum Solids, B Cowan, Wj Mullin, E Nelson
William J. Mullin
A moment method is used to compute the anisotropic spin diffusion constant in two-dimensional (2D) adsorbed and bulk (3D) quantum solids in which the spin motion is induced by an exchange Hamiltonian. Computations are carried out in 2D for the square and triangular lattices and in 3D for the hcp lattice. It is assumed that there are pair and three-particle exchange processes only. Since, in hcp3He, exchange processes out of the basal planeJprime may occur at a different rate from processes in the planeJ, comparison with experimental results on single crystals should allow the determination ofJ andJprime. Our results are …
The Origin Of The Phase In The Interference Of Bose-Einstein Condensates, Wj Mullin, R Krotkov, F Laloe
The Origin Of The Phase In The Interference Of Bose-Einstein Condensates, Wj Mullin, R Krotkov, F Laloe
William J. Mullin
We consider the interference of two overlapping ideal Bose-Einstein condensates. The usual description of this phenomenon involves the introduction of a condensate wave function with a definite phase. We investigate the origin of this phase and the theoretical basis of treating interference. It is possible to construct a phase state for which the particle number is uncertain, but the phase is known. How such a state would be prepared before an experiment is not obvious. We show that a phase can also arise from experiments using condensates with known particle numbers. The analysis of measurements in such states also gives …
Nmr Relaxation-Times For A Dilute Polarized Fermi Gas, Wj Mullin, F Laloe, Mg Richards
Nmr Relaxation-Times For A Dilute Polarized Fermi Gas, Wj Mullin, F Laloe, Mg Richards
William J. Mullin
We calculate the longitudinal relaxation time T1 for a polarized Boltzmann Image Fermi gas. We show that T1 is independent of polarization of the gas. At high T, where the thermal wavelength a is small compared to the scattering length a, T1 is proportional Image , while at low T, such that λ is greater than a, T1 is proportional to Image . T1 thus has a minimum at some intermediate temperature confirming the numerical results of Shizgal. The existence of the minimum does not depend on the presence of an attractive part of the potential. As an example of …
On The Snider Equation, F Laloe, Wj Mullin
On The Snider Equation, F Laloe, Wj Mullin
William J. Mullin
We study the physical content of the Snider quantum transport equation and the origin of a puzzling feature of this equation, which implies contradictory values for the one-particle density operator. We discuss in detail why the two values are in fact not very different provided that the studied particles have sufficiently large wave packets and only a small interaction probability, a condition which puts a limit on the validity of the Snider equation. In order to improve its range of application, we propose a reinterpretation of the equation as a ldquomixedrdquo equation relating the real one-particle distribution function (on the …
Bose-Einstein Condensation, Fluctuations, And Recurrence Relations In Statistical Mechanics, Wj Mullin, Jp Fernandez
Bose-Einstein Condensation, Fluctuations, And Recurrence Relations In Statistical Mechanics, Wj Mullin, Jp Fernandez
William J. Mullin
We calculate certain features of Bose–Einstein condensation in the ideal gas by using recurrence relations for the partition function. The grand canonical ensemble gives inaccurate results for certain properties of the condensate that are accurately provided by the canonical ensemble. Calculations in the latter can be made tractable for finite systems by means of the recurrence relations. The ideal one-dimensional harmonic Bose gas provides a particularly simple and pedagogically useful model for which detailed results are easily derived. An analysis of the Bose system via permutation cycles yields insight into the physical meaning of the recurrence relations.
Ursell Operators In Statistical Physics .3. Thermodynamic Properties Of Degenerate Gases, P Gruter, F Laloe, Ae Meyerovich, W Mullin
Ursell Operators In Statistical Physics .3. Thermodynamic Properties Of Degenerate Gases, P Gruter, F Laloe, Ae Meyerovich, W Mullin
William J. Mullin
We study in more details the properties of the generalized Beth Uhlenbeck formula obtained in a preceding article. This formula leads to a simple integral expression of the grand potential of any dilute system, where the interaction potential appears only through the matrix elements of the second order Ursell operator U2. Our results remain valid for significant degree of degeneracy of the gas, but not when Bose Einstein (or BCS) condensation is reached, or even too close to this transition point. We apply them to the study of the thermodynamic properties of degenerate quantum gases: equation of state, magnetic susceptibility, …
Spin Diffusion In Dilute, Polarized He-3-He-4 Solutions, Wj Mullin, Jw Jeon
Spin Diffusion In Dilute, Polarized He-3-He-4 Solutions, Wj Mullin, Jw Jeon
William J. Mullin
Spin dynamics for arbitrarily polarized and very dilute solutions of 3He in liquid 4He are described. We began at a very fundamental level by deriving a kinetic equation for arbitrarily polarized dilute quantum systems based on a method due to Boercker and Dufty. This approach allows more controlled approximations than our previous derivation based on the Kadanoff-Baym technique. Our previous work is here generalized to include T-matrix interactions rather than the Born approximation. Spin hydrodynamic equations are derived. The general equations are valid for both Fermi and Bose systems. By use of a well-known phenomenological potential to describe the 3He-3He …
Longitudinal Spin Relaxation In A Dilute, Degenerate Fermi Gas At Arbitrary Polarization, Ed Nelson, Wj Mullin
Longitudinal Spin Relaxation In A Dilute, Degenerate Fermi Gas At Arbitrary Polarization, Ed Nelson, Wj Mullin
William J. Mullin
We calculate the longitudinal magnetic relaxation timeT 1 –1 for a dilute, polarized Fermi gas with short range interactions at low temperatures. In the limit of small polarizationsT 1 –1 is proportional toT –2 in agreement with earlier predictions, while in the opposite caseT 1 –1 is strongly affected by polarization, and in the limit of large polarizations becomes proportional to the square of the energy separation between the Fermi surfaces for up and down spins. The possibility of measuringT 1 in dilute solutions of 3 He in superfluid 4 He is investigated.
Answer To Question #28 Bernoulli Equation, Wj Mullin
Answer To Question #28 Bernoulli Equation, Wj Mullin
William J. Mullin
Abstract unavailable
Proposed Nmr Determination Of The Exchange Parameters In Hexagonal-Close-Packed He-3, Wj Mullin, Ed Nelson
Proposed Nmr Determination Of The Exchange Parameters In Hexagonal-Close-Packed He-3, Wj Mullin, Ed Nelson
William J. Mullin
We calculate the relaxation times for an oriented single crystal of hexagonal-close-packed solid 3He, which, according to the theory of Roger and co-workers, is dominated by triple exchange. The anisotropy of the relaxation times is a function of the ratio of exchange rates in the basal plane to those out of the plane and may be used to determine this ratio. Results are presented for T1 and T2 as a function of frequency as well as of crystal orientation.
Theory Of Motional Inhibition Of Interlayer Quantum Tunneling In Thin He-3 Films, Wj Mullin, A Landesman
Theory Of Motional Inhibition Of Interlayer Quantum Tunneling In Thin He-3 Films, Wj Mullin, A Landesman
William J. Mullin
An attempt is made to interpret NMR data on 3He films for coverages just over one monolayer in terms of motion due to the quantum exchange of particles between layers. A summary of the relevant data and of various possible relaxation mechanisms is given and it is found that a portion of the data seems amenable to an interlayer exchange interpretation. The detailed theory of this process requires the use of the exchange operator concept and a Kubo-theory treatment of the effect of second-layer motion on the exchange process. It is shown that the ldquobarerdquo interlayer exchange process characterized by …
Viscosity Increase Upon Spin Polarization Of A Dilute Fermi Gas, D Candela, Lj Wei, Dr Mcallaster, Wj Mullin
Viscosity Increase Upon Spin Polarization Of A Dilute Fermi Gas, D Candela, Lj Wei, Dr Mcallaster, Wj Mullin
William J. Mullin
A vibrating-wire technique has been used to directly measure the viscosity increase in a dilute 3-4He solution caused by brute-force spin polarization up to 40%. The viscosity of a solution with degeneracy temperature TF=19.5 mK was measured over the temperature range 6.1–100 mK in magnetic fields of 1.00 and 7.96 T. Spin polarization caused a marked decrease in the mechanical Q of the viscometer at low temperatures. The observed viscosity is compared with calculations of the transport coefficients of dilute quantum gases for all temperatures and spin polarizations.