共查询到20条相似文献,搜索用时 10 毫秒
1.
We consider a superfluid of trapped fermionic atoms and study the single vortex solution in the Ginzburg-Landau regime. We define simple analytical estimates for the main characteristics of the system, such as the vortex core size, temperature regimes for the existence of a vortex, and the effects of rotation and interactions with normal fermions. The parameter dependence of the vortex core size (healing length) is found to be essentially different from that of the healing length in metallic superconductors or in trapped atomic Bose-Einstein condensation in the Thomas-Fermi limit. This is an indication of the importance of the confining geometry for the properties of fermionic superfluids. 相似文献
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We study the dynamic structure factor for density and spin within the crossover from BCS superfluidity of atomic fermions to the Bose-Einstein condensation of molecules. Both structure factors are experimentally accessible via Bragg spectroscopy and allow for the identification of the pairing mechanism: the spin structure factor allows for the determination of the two particle gap, while the collective sound mode in the density structure reveals the superfluid state. 相似文献
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M. Benarous H. Chachou-Samet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(2):125-132
We rely on a variational approach to derive a set of equations governing a trapped self-interacting Bose gas at finite temperature.
In this work, we analyze the static situation both at zero and finite temperature in the Thomas-Fermi limit for the repulsive
case. We derive simple analytic expressions for the condensate properties at finite temperature. The noncondensate and anomalous
density profiles are also analyzed in terms of the condensate fraction. The results are quite encouraging owing to the simplicity
of the formalism. 相似文献
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We present majority and minority radio frequency spectra of strongly interacting imbalanced Fermi gases of 6Li. We observed a smooth evolution in the nature of pairing correlations from pairing in the superfluid region to polaron binding in the highly polarized normal region. The imbalance induces quasiparticles in the superfluid region even at very low temperature. This leads to a local bimodal spectral response, which allowed us to determine the superfluid gap Delta and the Hartree energy U. 相似文献
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The quantum pressure correction to the excitation spectrum of the trapped superfluid Fermi gases in a BEC-BCS crossover
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Using quantum hydrodynamic approaches, we study the quantum pressure
correction to the collective excitation spectrum of the interacting
trapped superfluid Fermi gases in the BEC-BCS crossover. Based on a
phenomenological equation of state, we derive hydrodynamic equations
of the system in the whole BEC-BCS crossover regime. Beyond the
Thomas--Fermi approximation, expressions of the frequency
corrections of collective modes for both spherical and axial
symmetric traps excited in the BEC-BCS crossover are given
explicitly. The corrections of the eigenfrequencies due to the
quantum pressure and their dependence on the inverse interaction
strength, anisotropic parameter and particle numbers of the
condensate are discussed in detail. 相似文献
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Many-body atomic potentials, ?, are functions of the nuclear coordinates, and are defined by differences of ground state energies, E, e.g., ?(1, 2) ≡ E(1, 2) ? E(1) ? E(2). We prove that in Thomas-Fermi theory the n-body potential always has the sign (?1)n for all coordinates. We also prove that the remainder in the expansion of the total energy E in terms of the ?'s, when truncated at the n-body terms, has the sign (?1)n+1. 相似文献
11.
A one-configuration approximation is used to analyze the possibility of employing the frozen ion core model to calculate excited states with low-lying configurations of the same symmetry when the wave functions of the excited states are orthogonal to the function of the ground state. The nonorthogonality of the wave functions of different excited configurations is then weak. A calculation is made for certain Isns1S and 1s22sns1S terms of two-and four-electron ions, respectively, and the relaxation effects in the core are investigated for these excited states. This approximation is employed to obtain a variational equation for virtual orbitals allowing for the core relaxation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 71–77, June, 1980. 相似文献
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We theoretically analyze a single vortex in a spin polarized 3D trapped atomic Fermi gas near a broad Feshbach resonance. Above a critical polarization the Andreev-like bound states inside the core become occupied by the majority spin component. As a result, the local density difference at the core center suddenly rises at low temperatures. This provides a way to visualize the lowest bound state using phase-contrast imaging. As the polarization increases, the core expands gradually and the energy of the lowest bound state decreases. 相似文献
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Leadbeater M Winiecki T Samuels DC Barenghi CF Adams CS 《Physical review letters》2001,86(8):1410-1413
By performing numerical simulations based on the Gross-Pitaevskii equation, we make direct quantitative measurements of the sound energy released due to superfluid vortex reconnections. We show that the energy radiated expressed in terms of the loss of vortex line length is a simple function of the reconnection angle. In addition, we study the temporal and spatial distribution of the radiation and show that energy is emitted in the form of a sound pulse with a wavelength of a few healing lengths. 相似文献
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We have performed exact numerical calculations for a hydrogen atom perturbed by a uniform electric field for some Stark sublevels with n = 12, 13, 14, 15. The results are compared with recent experimental data for excited states of sodium. 相似文献
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We prove that the interaction among neutral atoms in Thomas-Fermi theory behaves, for large separationl, likel
–7. The constant is independent of the atomic nuclear charges, but does depend on the relative positions of the nuclei. We also show that is not a simple sum of pair terms, i.e. in TF theory three and higher body terms persist into the asymptotic (inl) region.Work partially supported by U.S. National Science Foundation grant MCS 75 21684 A02 相似文献
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E. V. Thuneberg 《Physica B: Condensed Matter》1995,210(3-4):287-299
It is well known that superfluids respond to rotation by forming vortex lines. It has been recently discovered that a different type of state consisting of a vortex sheet, instead of lines, can be created in the A phase of superfluid 3He. This paper presents an introduction to the vortex sheet. We first discuss 4He, where a vortex sheet is unstable. The way to realize a stable sheet in 3He-A is called a vortex soliton. It consists of a topologically stable domain wall to which nonsingular vorticity is bound. The vortex soliton has been observed by nuclear magnetic resonance, and its most prominent experimental properties are explained. The macroscopic shape of the sheet and the superfluid flow in a rotating container are discussed. 相似文献
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We discuss the energy eigenstates, ground and spin mixing dynamics of a spin-1 spinor Bose–Einstein condensate for a dilute atomic vapor confined in an optical trap. Our results go beyond the mean field picture and are developed within a fully quantized framework. 相似文献
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We examine the contribution of pairing fluctuations to the superfluid order parameter for harmonically trapped atomic Fermi gases in the BCS regime. In the limit of small systems we consider, both analytically and numerically, their space and temperature dependence. We predict a parity effect, i.e., that pairing fluctuations show a maximum or a minimum at the center of the trap, depending on the value of the last occupied shell being even or odd. We propose to detect pairing fluctuations by measuring the density-density correlation function after a ballistic expansion of the gas. 相似文献
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We discuss Bose-Einstein condensation in a trapped gas of bosonic particles interacting dominantly via dipole-dipole forces. We find that in this case the mean-field interparticle interaction and, hence, the stability diagram are governed by the trapping geometry. Possible physical realizations include ultracold heteronuclear molecules, or atoms with laser induced electric dipole moments. 相似文献