On translational superfluidity and the Landau criterion for Bose gases in the Gross-Pitaevski limit

The two-fluid and Landau criteria for superfluidity are compared for trapped Bose gases. While the two-fluid criterion predicts translational superfluidity, it is suggested, on the basis of the homogeneous Gross-Pitaevski limit, that a necessary part of Landau`s criterion, adequate for non-translationally invariant systems, does not hold for trapped Bose gases in the GP limit. As a consequence, if the compressibility is detected to be very large (infinite by experimental standards), the two-fluid criterion is seen to be the relevant one in case the system is a translational superfluid, while the Landau criterion is the relevant one if translational superfluidity is absent.

Coherence dynamics of two-mode condensates in asymmetric potentials

Detection of weak forces with an accuracy beyond the standard quantum limit holds promise both for fundamental research and for technological applications. Schemes involving ultracold atoms for such measurements are now considered to be prime candidates for increased sensitivity. In this paper we use a combination of analytical and numerical techniques to investigate the possible subshot-noise estimation of applied force fields through detection of coherence dynamics of Bose-condensed atoms in asymmetric double-well traps. Following a semiclassical description of the system dynamics and fringe visibility, we present numerical simulations of the full quantum dynamics that demonstrate the dynamical production of phase squeezing beyond the standard quantum limit. Nonlinear interactions are found to limit the achievable amount to a finite value determined by the external weak force.

Einstein Relation in n-Channel Inversion Layers of Nonlinear Optical, Optoelectronic and Related Materials: Simplified Theory, Relative Comparison and Suggestion for an Experimental Determination

In this paper, we study the Einstein relation for the diffusivity to mobility ratio (DMR) in n-channel inversion layers of non-linear optical materials on the basis of a newly formulated electron dispersion relation by considering their special properties within the frame work of k.p formalism. The results for the n-channel inversion layers of III-V, ternary and quaternary materials form a special case of our generalized analysis. The DMR for n-channel inversion layers of II-VI, IV-VI and stressed materials has been investigated by formulating the respective 2D electron dispersion laws. It has been found, taking n-channel inversion layers of CdGeAs2, Cd(3)AS(2), InAs, InSb, Hg1-xCdxTe, In1-xGaxAsyP1-y lattice matched to InP, CdS, PbTe, PbSnTe, Pb1-xSnxSe and stressed InSb as examples, that the DMR increases with the increasing surface electric field with different numerical values and the nature of the variations are totally band structure dependent. The well-known expression of the DMR for wide gap materials has been obtained as a special case under certain limiting conditions and this compatibility is an indirect test for our generalized formalism. Besides, an experimental method of determining the 2D DMR for n-channel inversion layers having arbitrary dispersion laws has been suggested.

Albert Einstein sitting on porch in rocking chair Portraits; Men

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Albert Einstein with violin, Josef Schwarz at piano, and Boris Schwarz in background; Haberlandstrasse 5, Berlin Portraits Groups; Men

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Albert Einstein with his son-in-law Rudolf Kayser Portraits Groups; Men

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Albert Einstein (front row, third from right) in school group portrait Portraits Groups

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Jakob Guggenheimer and his daughter Irene Einstein walking past antisemitic graffiti "Juden in Ulm nicht errwuenscht!" (Jews are not welcome in Ulm); Stuttgarterstrasse; Ulm/Donau Antisemitica

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Portrait of Albert Einstein in tempera (black and white) on cardboard Artworks

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Albert Einstein sitting on porch in rocking chair Portraits; Men

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Albert Einstein with his son-in-law Rudolf Kayser Portraits Groups; Men

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Jakob Guggenheimer and his daughter Irene Einstein walking past antisemitic graffiti "Juden in Ulm nicht errwuenscht!" (Jews are not welcome in Ulm); Stuttgarterstrasse; Ulm/Donau Antisemitica

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Albert Einstein in his study; Haberlandstrasse 5, Berlin Portraits Men

Signed Jacobi

Portrait of Albert Einstein in the Southern California desert Portraits; Men

Verso: "Er sinnt in der Wueste"

Albert Einstein laying on grass in a field Portraits; Men

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