We report on the first observation of a novel type of superconducting proximity network using a superconductor-normal metal bilayer. Little-Parks oscillation measurements show that the superconducting current flows through a path enclosed by the edge
rather than by the center of the Pb/Au wire in the network. Furthermore, several peaks were observed in a power spectrum analysis. We observed that the sequence of these peaks and that of the monolayer network were connected by the power function, which is a factor of the line width, S_{B_n} = alpha^{n-2}S_{A_n}. This suggests that even in a proximity network vortices are arranged in a way identical to a monolayer network.
We study pseudogap behaviors of ultracold Fermi gases in the BCS-BEC crossover region. We calculate the density of states (DOS), as well as the single-particle spectral weight, above the superfluid transition temperature $T_{rm c}$ including pairing
fluctuations within a $T$-matrix approximation. We find that DOS exhibits a pseudogap structure in the BCS-BEC crossover region, which is most remarkable near the unitarity limit. We determine the pseudogap temperature $T^*$ at which the pseudogap structure in DOS disappears. We also introduce another temperature $T^{**}$ at which the BCS-like double-peak structure disappears in the spectral weight. While one finds $T^*>T^{**}$ in the BCS regime, $T^{**}$ becomes higher than $T^*$ in the crossover and BEC regime. We also determine the pseudogap region in the phase diagram in terms of temperature and pairing interaction.
We report measurements of Little-Parks oscillation on the hierarchical honeycomb-superconducting network for investigating possible effects of hierarchical structure in terms of spatial symmetry, parity and duality. We observed an asymmetric Little-P
arks oscillation about $Phi/Phi_0 = 1/2$, although spatial symmetry was kept in the network. In comparison with a regular honeycomb network, the asymmetric oscillation is attributed to hierarchy which induces mixture of commensurate and incommensurate regions. The asymmetric oscillation is found to indicate breaking of the duality of vortex configuration.
We investigate tunneling properties of Bogoliubov phonons in a Bose-Einstein condensate. We find the anomalous enhancement of the quasiparticle current $J_{rm q}$ carried by Bogoliubov phonons near a potential barrier, due to the supply of the excess
current from the condensate. This effect leads to the increase of quasiparticle transmission probability in the low energy region found by Kovrizhin {it et al.}. We also show that the quasiparticle current twists the phase of the condensate wavefunction across the barrier, leading to a finite Josephson supercurrent $J_{rm s}$ through the barrier. This induced supercurrent flows in the opposite direction to the quasiparticle current so as to cancel out the enhancement of $J_{rm q}$ and conserve the total current $J=J_{rm q}+J_{rm s}$.
