arXiv subjects

S. Kurihara

Publications and source records attributed to S. Kurihara.

3 recordsLinked to original sources

arXiv2000

Quantum Phase Transition in Extended Attractive Hubbard Model

We have made a variational analysis on an evolution of superconductivity from weak to strong coupling regime. In contrast to a crossover without thermodynamic anomaly found in a dilute system, we show the existence of a quantum phase transition near half filling. The transition is driven by charge density waves instabilities. We have found that superconductivity and charge density waves coexist in the presence of a weak intersite repulsion. The ground state phase diagram is determined and the quantum phase transition is an attractive version of the Mott transition.

cond-mat.supr-con↗

arXiv1999

Intrinsic Resistivity via Quantum Nucleation of Phase Slips in a One-Dimensional Josephson Junction Array

The resistivity of a one-dimensional Josephson junction array at zero temperature is calculated by estimating the nucleation rate of quantum phase slips. We choose a certain collective coordinate which describes the nucleation process and estimate the corresponding effective mass. In the strong coupling regime, where Josephson coupling energy exceeds the charging energy, we calculate the nucleation rate by means of WKB method. Our estimation is in good agreement with recent experimental data. The superconductor-insulator transition point is also discussed.

cond-mat.supr-con↗

arXiv1999

Decay of Superflow Confined in Thin Torus: A Realization of Tunneling Quantum Fields

The quantum nucleation of phase slips in neutral superfluids confined in a thin torus is investigated by means of the collective coordinate method. We have devised, with numerical justification, a certain collective coordinate to describe the quantum nucleation process of a phase slip. Considering the quantum fluctuation around the local minimum of the action, we calculate the effective mass of the phase slip. Due to the coherence of the condensate throughout the torus, the effective mass is proportional to the circumference L of the torus, and the decay rate has a strong exponential L-dependence.

cond-mat↗