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Investigations with various inner shielding distance tests for a novel coupler-based CPT system applied for electric vehicles using electromagnetic resonant coupling and aluminium shielding material
Contactless power transfer (CPT) technology development has been driven rapidly over the past decade by the world-wide trends towards new energy explorations, and numerous reports have been presented in this area. This paper focuses on passive magnetic shielding, which acts as one of the major factors mainly determining the overall CPT system performance when discussing electromagnetic field flux distribution and its real-time effects on magnetic resonant coupling. As a well performance conductive metallic material, aluminium has been adopted to be a passive shielding material in the designed novel H-shape coupler CPT system in this paper, in order to evaluate and find out the optimal inner shielding distance in between the coil and the inner shielding shell. Three inner shielding distances are applied and analyzed across a critical range of system operating frequency, by which the actual CPT system performance differences from perspectives of electromagnetics and power electronics have been illustrated and compared. As a result, it can be noticed that the 15-mm inner shielding gap CPT model is able to yield an optimal system performance with a maximum system efficiency, peak system output RMS power of over 36% and 22 kW, respectively, which also shows an optimal capability to address major concerns over electric vehicle contactless charging. Besides, along with the electromagnetic field parameters generated in the model, such as actual real-time values of flux linkage, magnetic flux density and field strength, it can be found that the 15-mm inner shielding gap prototype is able to achieve better overall magnetic field performance than 5-mm and 25-mm inner shielding distance CPT models
Conditions for entanglement transformation between a class of multipartite pure states with generalized Schmidt decompositions
In this note we generalize Nielsen's marjoization criterion for the
convertibility of bipartite pure states [Phys. Rev. Lett \textbf{83},
436(1999)] to a special class of multipartite pure states which have
generalized Schmidt decompositions.Comment: 3 pages (Revetex 4), no figures. A brief note on entanglement
transformation. Comments are welcom
Dynamical Response of Fermi Condensate to Varying Magnetic Fields
We investigate the dynamical response of strongly interacting ultra-cold
fermionic atoms near Feshbach resonance to varying magnetic fields. Following
the experimental practices, we calculate the response of the atoms to
oscillating and to linearly ramped magnetic fields respectively. For
oscillating magnetic fields, depending on the frequencies and the amplitudes of
the oscillations, the response of the pair excitation gap shows either linear
or rich non-linear behaviour. In addition, both the spectral studies through
the linear response theory and the time-domain simulations suggest the
existence of a resonant frequency corresponding to the pair dissociation
threshold. For linearly ramped magnetic fields, the response of the excitation
gap shows damped oscillations. The final value of the excitation gap depends on
the rate of the field sweep.Comment: 6 pages, 6 figure
Detecting the breached pair phase in a polarized ultracold Fermi gas
We propose a method for the experimental detection of a new quantum phase,
the breached pair state, in a strongly interacting ultracold Fermi gas with
population imbalance. We show that through the time-of-flight Raman imaging,
the presence of such a phase can be unambiguously determined with a measurement
of the momentum-space phase separation of the minority spin component. To guide
the experimental efforts, the momentum-space density profiles are calculated
under typical experimental conditions.Comment: 4 pages, 3 figures, replaced with the published versio
Trapped Fermions across a Feshbach resonance with population imbalance
We investigate the phase separation of resonantly interacting fermions in a
trap with imbalanced spin populations, both at zero and at finite temperatures.
We directly minimize the thermodynamical potential under the local density
approximation instead of using the gap equation, as the latter may give
unstable solutions. On the BEC side of the resonance, one may cross three
different phases from the trap center to the edge; while on the BCS side or at
resonance, typically only two phases show up. We compare our results with the
recent experiment, and the agreement is remarkable.Comment: 4 pages, 3 figures, replaced with the published versio
BCS-BEC crossover and quantum phase transition for 6Li and 40K atoms across Feshbach resonance
We systematically study the BCS-BEC crossover and the quantum phase
transition in ultracold 6Li and 40K atoms across a wide Feshbach resonance. The
background scattering lengths for 6Li and 40K have opposite signs, which lead
to very different behaviors for these two types of atoms. For 40K, both the
two-body and the many-body calculations show that the system always has two
branches of solutions: one corresponds to a deeply bound molecule state; and
the other, the one accessed by the current experiments, corresponds to a weakly
bound state with population always dominantly in the open channel. For 6Li,
there is only a unique solution with the standard crossover from the weakly
bound Cooper pairs to the deeply bound molecules as one sweeps the magnetic
field through the crossover region. Because of this difference, for the
experimentally accessible state of 40K, there is a quantum phase transition at
zero temperature from the superfluid to the normal fermi gas at the positive
detuning of the magnetic field where the s-wave scattering length passes its
zero point. For 6Li, however, the system changes continuously across the zero
point of the scattering length. For both types of atoms, we also give detailed
comparison between the results from the two-channel and the single-channel
model over the whole region of the magnetic field detuning.Comment: 7 pages, 6 figure
Effective Hamiltonian for fermions in an optical lattice across Feshbach resonance
We derive the Hamiltonian for cold fermionic atoms in an optical lattice
across a broad Feshbach resonance, taking into account of both multiband
occupations and neighboring-site collisions. Under typical configurations, the
resulting Hamiltonian can be dramatically simplified to an effective
single-band model, which describes a new type of resonance between the local
dressed molecules and the valence bond states of fermionic atoms at neighboring
sites. On different sides of such a resonance, the effective Hamiltonian is
reduced to either a t-J model for the fermionic atoms or an XXZ model for the
dressed molecules. The parameters in these models are experimentally tunable in
the full range, which allows for observation of various phase transitions.Comment: 5 pages, 2 figure
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