The three-bit balanced ternary quantum voltage generator was designed and tested. This voltage generator is based on zero-crossing Shapiro steps (ZCSSs) in asymmetric two-junction SQUID. ZCSSs were observed on the current-voltage curves, and maximum and minimum current of ZCSSs were almost same, respectively for the three bits. 27-step quantum voltages from -13Φ0f to +13 Φ0f were observed by combinations of inputs of bit1, bit2 and bit3.

In this paper, we review the progress in BiSrCaCuO-2212 Intrinsic Josephson junctions (IJJs) by summarizing our recent results in fabrication and high frequency experiments. Using a double-side fabrication process, a well defined number of intrinsic Josephson junctions in a well defined geometry can be fabricated. The junctions in the stack are quite homogeneous, and the power distribution of external irradiation among the junctions is even. Shapiro steps are clearly observed up to 2.5 THz, and the general condition for the occurrence of Shapiro steps at frequency frf is that it should be much greater than the plasma frequency fpl. Under certain conditions the Shapiro steps are zero-crossing, making some applications possible, such as quantum voltage standard etc.

We present analytical and numerical results on the flux-quantum transitions in a three-junction superconducting quantum interference device (3J-SQUID) controlled by two RF signals. The 3J-SQUID has two superconducting loops, and the RF signals are magnetically coupled to the loops. Flux-quantum transitions in the 3J-SQUID loops can be controlled by utilizing the phase difference of the two RF signals. Under proper conditions, we can obtain a situation where one flux quantum passes through the 3J-SQUID per one cycle of the RF signals without DC current biasing, which results in a zero-crossing step on the current-voltage characteristics. In this paper, we first explain the operation principle by using a quantum state diagram of a 3J-SQUID. Next, we numerically simulate RF-induced transitions of the quantum states. A zero-crossing step on the current-voltage characteristics is demonstrated. We also investigate dependence of zero-crossing steps upon parameters of the 3J-SQUID and RF signals.

We previously proposed a robust hybrid edge detector which relaxes the trade off between robustess against noise and accurate localization of the edges. This hybrid detector separates the tasks of localization and noise suppresion between two sub-detectors. In this paper, we present an extension to this hybrid detector to determine its optimal parameters, independently of the scene. This extension defines a probabilistic cost function using for criteria the probability of missing an edge buried in noise and the probability of detecting false edges. The optimization of this cost function allows the automatic selection of the parameters of the hybrid edge detector given the height of the minimum edge to be detected and the variance of the noise, σ2n. The results were applied to the 2D case and the performance of the adaptive hybrid detector was compared to other detectors.

A method of planar curve classification, which is invariant to rotation, scaling and translation using the zerocrossings representation of wavelet transform was introduced. The description of the object is represented by taking a ratio between its two adjacent boundary points so it is invariant to object rotation, translation and size. Transforming this signal to zero-crossings representation using wavelet transform, the minimum distance between the object and model while shifting the signals each other, can be used as classification parameter.