Topological Excitations in Spinor Bose-Einstein Condensates

We investigate the properties of skyrmion in the ferromagnetic state of spin-1 Bose-Einstein condensates by means of the mean-field theory and show that the size of skyrmion is fixed to the order of the healing length. It is shown that the interaction between two skyrmions with oppositely rotating spin textures is attractive when their separation is large, following a unique power-law behavior with a power of -7/2.Comment: 4 pages, 5 figure

Josephson Current between Triplet and Singlet Superconductors

The Josephson effect between triplet and singlet superconductors is studied. Josephson current can flow between triplet and singlet superconductors due to the spin-orbit coupling in the spin-triplet superconductor but it is finite only when triplet superconductor has $L_z=-S_z=\pm 1$, where $L_z$ and $S_z$ are the perpendicular components of orbital angular momentum and spin angular momentum of the triplet Cooper pairs, respectively. The recently observed temperature and orientational dependence of the critical current through a Josephson junction between UPt$_3$ and Nb is investigated by considering a non-unitary triplet state.Comment: 4 pages, no figure

The effect of test system misalignment in the dynamic tension test

The effects of test system misalignment are analyzed for dynamic tension tests using sheet type rectangular 1100-0 aluminum specimens. The strain rate is assumed constant only on the natural axis of the specimen even though the specimen is subjected to a constant strain rate test. The results include: (1) the lower the strain rate, the more significant the misalignment errors become; (2) misalignment errors of 50% are found at the extreme fibers of the specimen; (3) the strain rate variation in the cross section decreases with increasing plastic strain and vanishes at plastic strain equal to 0.8% at the midspan of the specimen; and (4) the neutral axis shifts toward the centerline of the specimen as the plastic strain increases, but it reaches a limit and does not completely move back to the centerline

Asymmetric Fermi superfluid in a harmonic trap

We consider a dilute two-component atomic fermion gas with unequal populations in a harmonic trap potential using the mean field theory and the local density approximation. We show that the system is phase separated into concentric shells with the superfluid in the core surrounded by the normal fermion gas in both the weak-coupling BCS side and near the Feshbach resonance. In the strong-coupling BEC side, the composite bosons and left-over fermions can be mixed. We calculate the cloud radii and compare axial density profiles systemically for the BCS, near resonance and BEC regimes.Comment: 15 pages, 5 figure

A Pairing-free Provable Secure and Efficient Identity-based Identification Scheme with Anonymity

In this paper, we propose a Blind Identity-Based Identification (Blind IBI) scheme based on the Guillou-Quisquater (GQ) scheme. Our proposed scheme combines the benefits of traditional Identity-Based Identification (IBI) schemes that can authenticate a user’s identity without rely ing on a trusted third party with the Blind Signature (BS) scheme that provides anonymity. As a result, the proposed scheme assures absolute user privacy during the authentication process. It does not rely on a third party, yet the verifier can still be assured of the user’s identity with out the user actually revealing it. In our work, we show that the proposed scheme is provably secure under the random oracle model, with the assumption that the one-more-RSA-inversion problem is difficult. Furthermore, we demonstrate that the proposed scheme is secure against passive, active, and concurrent impersonation attacks. In conclusion, the proposed scheme is able to achieve the desired blindness property without compromising the security of the GQ-IBI scheme it is based upon

Electronic State and Magnetic Susceptibility in Orbitally Degenerate (J=5/2) Periodic Anderson Model

Magnetic susceptibility in a heavy fermion systemis composed of the Pauli term (\chi_P) and the Van-Vleck term (\chi_V). The latter comes from the interband excitation, where f-orbital degeneracy is essential. In this work, we study \chi_P and \chi_V in the orbitally degenerate (J=5/2) periodic Anderson model for both the metallic and insulating cases. The effect of the correlation between f-electrons is investigated using the self-consistent second-order perturbation theory. The main results are as follows. (i) Sixfold degenerate model: both \chi_P and \chi_V are enhanced by a factor of 1/z (z is the renormalization constant). (ii) Nondegenerate model: only \chi_P is enhanced by 1/z. Thus, orbital degeneracy is indispensable for enhancement of \chi_V. Moreover, orbital degeneracy reduces the Wilson ratio and stabilizes a nonmagnetic Fermi liquid state.Comment: 4 pages, revtex, to be published in J. Phys. Soc. Jpn. (No.8