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The Equilibrium Properties of the Polarized Dipolar Fermi Gases 报告人:张静宁 导师:易俗
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Outline: Polarized Dipolar Fermi Gases Motivation and model Methods Hartree-Fock & local density approximation Minimization of the free energy functional Self-consistent field equations Results (normal phase) Zero-temperature Finite-temperature Summary
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Model Physical System Fermionic Polar Molecules ( 40 K 87 Rb ) Spin polarized Electric dipole moment polarized Normal Phase Second-quantized Hamiltonian
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Dipole-dipole Interaction Polarized dipoles (long-range & anisotropic) Tunability Fourier Transform
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Containers Box: homogenous case Harmonic potential: trapped case y z x Oblate trap: >1 Prolate trap: <1
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Theoretical tools for Fermi gases
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Energy functional: Preparation Energy functional Single-particle reduced density matrix Two-particle reduced density matrix
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Wigner distribution function zero-temperature finite temperature
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Free energy functional Total energy: Fourier transform Free energy functional (zero-temperature): Minimization: The Simulated Annealing Method
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Self-consistent field equations: Finite temperature Independent quasi-particles (HFA) Fermi-Dirac statistics Effective potential Normalization condition
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Result: Zero-temperature (1) Ellipsoidal ansatz T. Miyakawa et al., PRA 77, 061603 (2008); T. Sogo et al., NJP 11, 055017 (2009).
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Result: Zero-temperature (2) Density distribution Stability boundary Collapse Global collapse Local collapse
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Result: Zero-temperature (3) Phase-space deformation Always stretched alone the attractive direction Interaction energy (dir. + exc.)
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Result: Finite-temperature & Homogenous Dimensionless dipole-dipole interaction strength Phase-space distribution Phase-space deformation Thermodynamic properties Energy Chemical potential Entropy Specific heat Pressure
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Result: Finite-temperature & Trapped Dimensionless dipole-dipole interaction strength Stability boundary Phase-space deformation
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Summary The anisotropy of dipolar interaction induces deformation in both real and momentum space. Variational approach works well at zero-temperature when interaction is not too strong, but fails to predict the stability boundary because of the local collapse. The phase-space distribution is always stretched alone the attractive direction of the dipole-dipole interaction, while the deform is gradually eliminated as the temperature rising.
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