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We demonstrate the operation of a coincidence photon detector with a short timing jitter consisting of two superconducting nanowire single photon detectors (SSPDs) and a single flux quantum (SFQ) circuit. By utilizing the timing discrimination capability of the SFQ coincidence circuit, the full width at half maximum timing jitter of the entire coincidence photon detector was evaluated as 32.3 ps, which is 36 ps less than that of the standard commercial time correlated single photon counting module, and the timing jitter of the SSPD was estimated as ∼15 ps. Owing to the short timing jitter characteristics, our coincidence photon detector could correctly capture the effect of pulse-width broadening by insertion of an optical bandpass filter. We have also demonstrated that our coincidence photon detection clearly shows Hong-Ou-Mandel interference with a weak coherent pulse. These results are a crucial step to realizing high timing resolution coincidence measurements, ushering in a technology for timing measurement based multi-photon quantum interference. [ABSTRACT FROM AUTHOR]

The control of the critical current density (J[sub c]) and the junction resistance (R[sub N]) along the c axis of intrinsic Josephson junctions (IJJs) on a high-T[sub c] superconductor is very important for applying the IJJs to electronic devices. For controlling these junction parameters, we have clarified the relationship of J[sub c], R[sub N], and the carrier density in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+δ] (Bi-2212) whiskers by changing the carrier density with an annealing process. As a result, the J[sub c] decreased, and the R[sub N] increased systematically when the carrier density decreased. The values of J[sub c] and R[sub N] could be controlled by a change in the carrier density. [ABSTRACT FROM AUTHOR]

Using a double-side fabrication method, a stack of intrinsic Josephson junctions plus a bow-tie antenna and chokes were made in a slice 200 nm thick and singled out from inside a bulk Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] single crystal. The junctions in the fabricated stack were very uniform, and the number of junctions involved was rather controllable. Potentially it would be possible to use this method to fabricate integrated circuits based on intrinsic Josephson junctions in high T[sub C] superconductors. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Reports on the fabrication of submicron-sized intrinsic Josephson junctions by the focused-ion-beam etching method. Reduction of the in-plane junction area without degradation in the critical transition temperature; Gap structure and normal state resistance observed; Coulumb staircase structure.

The distributions of optical emission intensity along the discharge axis in multiple-parallel-plate ac glow discharges were measured in the presence of a magnetic field perpendicular to the discharge electric field. In a SiH4(10%)/Ar discharge, time-averaged spectroscopic measurements showed that profile control of not only plasmas but also SiH* was possible by varying the field strength. The emission intensity of SiH* was increased with the field strength. These results suggest that the present new configuration with cross magnetic field can make thin films on a large-area substrate outside the multielectrodes uniform and can enhance the deposition rate. [ABSTRACT FROM AUTHOR]

Examines the transport characteristics of grain boundary junctions in Tl[sub 2]Ba[sub 2]CaCu[sub 2]O[sub 8] bicrystals. Details on current densities and current-voltage curves; Mechanism of patterning microbridges at grain boundaries; Relation of critical current density to misorientation angles.

The Ag-coated superconducting Bi2 Sr2 CaCu2 Ox glass-ceramic fibers were successfully prepared. The glass fibers with a length of 50 cm, a width of 100–200 μm, and a thickness of about 20 μm were first drawn from glass plates with a thickness of 1 mm and then silver pastes were coated on the smooth surface of glass fibers. The Ag-coated glass fibers were converted into superconductors after annealing at temperatures of 820–860 °C. The main crystalline phase in the glass-ceramic fibers was the superconducting low Tc phase. The Ag-coated glass-ceramic fibers obtained by annealing at 840 °C for 5 h in air exhibited superconductivity with a Tc (zero)=70 K and a critical current density (60 K, zero magnetic field) of more than 40 A/cm2 . [ABSTRACT FROM AUTHOR]

Superconducting glass ceramics of Bi0.8Pb0.2SrCaCu1.5Oy (sample A) and BiPb0.2SrCaCu1.5Oy (sample B) have been prepared by using the melt quenching method. It was found that the volume fraction of the high Tc phases in sample A annealed at 830 or 840 °C for 250 h was much higher than that in sample B. The annealed (840 °C, 250 h) sample A exhibited superconductivity with a Tc (zero) of 100 K and a critical current density (77 K, zero magnetic field) of 120 A/cm2. [ABSTRACT FROM AUTHOR]

We reveal the intrinsic Josephson effect in a La[sub 2-x]Sr[sub x]CuO[sub 4] (LSCO) high-T[sub c] superconductor. Nb counterelectrodes are deposited on top of mesas, which are formed on surfaces either parallel or perpendicular to the ab plane of LSCO single crystals. Nb/LSCO interfaces behave as SNS Josephson junctions. For the junctions parallel to the ab plane, we observe many branches in the current–voltage characteristics due to intrinsic Josephson effects. The voltage gaps between the branches are typically 0.1 mV, which is much smaller than the superconducting energy gap 2Δ≅11 mV expected for LSCO from Bardeen–Cooper–Schrieffer theory. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]