We report a demonstration of S-I-S quasiparticle tunneling in c-axis oriented planar junctions consisting of YBaCuO͞PrBaCuO͞HoBaCuO thin film heterostructures. In the conductance curves at low temperatures well developed peaks indicative of gap structures are found at 645 mV. The high bias conductance shows flat dependence on energy and the best quality junction has a zero-bias conductance less than 0.05 of the normal state value. We discuss our spectra in the framework of a BCS-like density of states as well as in terms of a d x 2 2y 2 symmetry of the superconducting order parameter. PACS numbers: 74.50.+r, 74.80.Dm Tunneling studies in high-T c heterostructures composed of superconducting-insulating-superconducting ͑S-I-S͒ layers are of great interest from both a fundamental and a technological point of view. Junction characteristics in fact can provide important information on the quasiparticle density of states and on the mechanism responsible for superconductivity which still are open questions about high-T c superconductors (HTS). On the other hand, trilayers are the basic structure for high-frequency transmission lines, for filters, and for the realization of Josephson junctions for high-T c integrated circuits.Problems associated with multilayer structures arise from the insulating barriers and interfaces. Barrier materials need to have a close lattice match and compatible deposition conditions with the HTS in order to propagate epitaxial growth. Formation of good quality interfaces is also important. The roughness of the surfaces can produce the mixing of properties of different directions in these anisotropic materials. In addition, due to the extremely short coherence length j, the superconducting properties are easily degraded at the interfaces. To overcome this last difficulty, superconductor-normal-superconductor ͑S-N-S͒ junctions have been developed for Josephson devices, since, due to the proximity effect, they show Josephson coupling even if the metal barrier thickness is greater than j.Recently, different kinds of all-oxide S-N-S structures, including grain boundary, step edge, ramp-type, and sandwich-type junctions, have been realized by several groups for high-T c device applications. In particular, YBa 2 Cu 3 O 72d ͞PrBa 2 Cu 3 O 72d 0 ͞YBa 2 Cu 3 O 72d junctions have been investigated in detail by using a-axis oriented [1-3] and, more recently, (103)-oriented films [4].In contrast with the excellent results obtained in Josephson coupled S-N-S trilayers, clear evidence for quasiparticle tunneling is difficult to obtain in alloxide S-I-S junctions. Several attempts to realize HTS-I-HTS structures have been reported in the literature., and Bi 2 -Sr 2 CaCu 2 O 8 ͞Bi 2 Sr 2 YCu 2 O 8 ͞Bi 2 Sr 2 CaCu 2 O 8 junctions [8] have been measured. However, in all these structures, due to the difficulty of realization of good quality interfaces between the insulating barrier and the counterelectrodes, quasiparticle tunneling shows a S-I-N behavior with gaplike features developed well below the measured ...

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We have deposited Bi2Sr2CaCu2O8+δ/Bi2Sr2YCu2O8+δ/Bi2Sr2CaCu2 O+δ (2212/22Y2/2212) heterostructures by an in situ dc sputtering technique at high oxygen pressures on (001) SrTiO3 substrates. The formation of highly c-axis oriented trilayers with sharp interfaces is demonstrated by x-ray diffraction and transmission electron microscope (TEM) analysis. Both the top and the bottom 2212 layers are superconducting below 87 K. Tunneling phenomena on junctions fabricated from these trilayers are observed. The conductance versus voltage curves at low temperatures exhibit a change of slope indicative of a gap structure at about 30 mV, a zero-bias peak, as well as linear background at high voltages.

Robot map navigation and localization are challenging tasks that require the solving of the data association problem for local and global features. Data fusion allows the advantages of two or more sensors to be combined, and complementary cooperation can be obtained. This paper presents two methods to embed depth information in omnidirectional images using the extrinsic calibration of a 2D laser range finder and a central catadioptric camera. The methods presented do not require a visible laser beam, but they assume the planar checkerboard patterns are visible for both the catadioptric camera and the 2D laser range finder. Unlike other approaches, the methods proposed used an invisible laser trace, and they are evaluated at pixel error level using ground truth data from the calibration patterns projected in the omnidirectional image. Results include a mean square error analysis of all calibration poses, and laser point projection on indoor omnidirectional images. We think that embedding range information in omnidirectional images is an interesting tool for data fusion approaches, which can be used in robot map building and localization.