Detail of a washboard potential in the RCSJ model for a finite bias. represents the energy barrier. denotes thermal activation (dotted line), and MQT processes with low (solid line) and high (dashed line) dissipation,15 from the ground state and the first excited state, respectively, are indicated. Microwaves can induce a transition from the ground to the first exited state.
(a) Sketch of the grain boundary structures in biepitaxial (b)-based out-of-plane biepitaxial junctions. The produces an additional 45° in-plane rotation of the YBCO axes with respect to the in-plane directions of the substrate. (b) Normalized critical current density vs. angle for two sets of c-axis tilt biepitaxial YBCO junctions, with widths of (triangles) and (stars). The solid curves connecting the symbols are guides for the eye. The dotted curve is the Sigrist-Rice-like formula assuming pure pairing symmetry in this geometry.41 (c) I–V curves as a function of the magnetic field. A Fraunhofer profile of the critical current can be seen. The misorientation angle is 60° in this case. (d) Scanning SQUID microscope image of a area, including tilt-tilt and twist-tilt in -based biepitaxial GBs. The GBs are marked by the presence of spontaneous currents. The sample was cooled and imaged at in nominally zero field. Adapted from Ref. 43.
Switching current probability distribution for at for different bath temperatures . The inset shows the switching current probability distribution measured at along with the original I–V curve. Adapted from Bauch et al. 30
The measured saturates below , indicating a crossover from the thermal to the quantum regime. The width for and the data for are shown in the inset. Adapted from Bauch et al. 30
The measured switching current probability distribution P(I) in the presence of microwaves at a frequency of and at a temperature . The applied power at the room temperature terminal varies from . The MQT processes corresponding to the switching current probability distribution P(I) are shown on the right. Adapted from Bauch et al. 31
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