Nonuniversal Magnetic-Field Correlation of Conductance Fluctuations in Quantum Cavities Attached to a Superconductor

抄録

We investigate the magnetic-field-induced transmission resonance in two-dimensional-electron-gas--superconductor junctions. The magnetic-field correlation of the conductance fluctuations is nonuniversal at low magnetic fields provided the normal region has a certain kind of rectangular-shape. The anomalous magnetoconductance fluctuations are robust against the imperfection of the quantum cavity geometry and the occupation of multiple modes in the normal lead. However, the anomalous fluctuations are suppressed if the cavity size is not sufficiently large in comparison to the lead width. This indicates the importance of multiple Andreev reflection for the anomalous behavior. The wave function at the resonance in the anomalous fluctuations regime reveals scars by regular classical orbits. Hierarchical nature of the anomalous conductance fluctuations is evidenced by the distributions of the current and the charge.