Transfer of autocollimator calibration for use with scanning gantry profilometers for accurate determination of surface slope and curvature of state of the art x ray mirrors

X ray optics, desired for beamlines at free electron laser and diffraction limited storage ring x ray light sources, must have almost perfect surfaces, capable of delivering light to experiments without significant degradation of brightness and coherence. To accurately characterize such optics at an optical metrology lab, two basic types of surface slope profilometers are used the long trace profilers LTPs and nanometer optical measuring NOM like angular deflectometers, based on electronic autocollimator AC ELCOMAT 3000. The inherent systematic errors of the instrument s optical sensors set the principle limit to their measuring performance. Where autocollimator of a NOM like profiler may be calibrated at a unique dedicated facility, this is for a particular configuration of distance, aperture size, and angular range that does not always match the exact use in a scanning measurement with the profiler. Here we discuss the developed methodology, experimental set up, and numerical methods of transferring the calibration of one reference AC to the scanning AC of the Optical Surface Measuring System OSMS , recently brought to operation at the ALS Xray Optics Laboratory. We show that precision calibration of the OSMS performed in three steps, allows us to provide high confidence and accuracy low spatial frequency metrology and not print into measurements the inherent systematic error of tool in use. With the examples of the OSMS measurements with a state of the art x ray aspherical mirror, available from one of the most advanced vendors of X ray optics, we demonstrate the high efficacy of the developed calibration procedure. The results of our work are important for obtaining high reliability data, needed for sophisticated numerical simulations of beamline performance and optimization of beamline usage of the optics. This work was supported by the U. S. Department of Energy under contract number DE AC02 05CH1123

Counting statistics of coherent population trapping in quantum dots

Destructive interference of single-electron tunneling between three quantum dots can trap an electron in a coherent superposition of charge on two of the dots. Coupling to external charges causes decoherence of this superposition, and in the presence of a large bias voltage each decoherence event transfers a certain number of electrons through the device. We calculate the counting statistics of the transferred charges, finding a crossover from sub-Poissonian to super-Poissonian statistics with increasing ratio of tunnel and decoherence rates.Comment: 4 pages, 2 figure

Verkalkung der Falx cerebri: Ein pathognomonisches Zeichen beim Gorlin-Goltz-Syndrom

Zusammenfassung: Hintergrund: Das Gorlin-Goltz-Syndrom (syn. Basalzellnävussyndrom) ist ein autosomal-dominant vererbtes Krankheitsbild, das sich in charakteristischer Weise anhand von Keratozysten der Kiefer, multiplen Basaliomen, skelettalen Deformationen und intrakraniellen Kalzifizierungen manifestiert. Methode: In der vorliegenden Studie wurden 4787 Röntgenaufnahmen mit okzipitomentalem Strahlengang aus dem Archiv der Klinik für Zahn-, Mund- und Kieferheilkunde der Christian-Albrechts-Universität Kiel auf das Vorliegen von Kalzifikationen im Bereich der Falx cerebri geprüft. Ergebnisse: Dabei kristallisierten sich charakteristische Erscheinungsbilder dieser Abweichungen heraus, die 4 lamellaren Strukturgruppen zugeordnet werden konnten. Die Strukturen der Gruppe4 konnten nur bei Gorlin-Goltz-Syndrom-Patienten gefunden werden und unterschieden sich in Form und Ausmaß von den restlichen 3Gruppen. Schlussfolgerung: Das plurilamellare Erscheinungsbild dieser Gruppe konnte als pathognomonisches Zeichen für das Basalzellnävussyndrom gewertet werde

The temperature-jump problem in rarefied-gas dynamics

An analytical version of the discrete-ordinates method is used here to solve the classical temperature-jump problem based on the BGK model in rarefied-gas dynamics. In addition to a complete development of the discrete-ordinates method for the application considered, the computational algorithm is implemented to yield very accurate results for the temperature jump and the complete temperature and density distributions in the gas. The algorithm is easy to use, and the developed code runs typically in less than a second on a 400 MHz Pentium-based PC.</jats:p

Three-tangle for mixtures of generalized GHZ and generalized W states

We give a complete solution for the three-tangle of mixed three-qubit states composed of a generalized GHZ state, a|000>+b|111>, and a generalized W state, c|001>+d|010>+f|100>. Using the methods introduced by Lohmayer et al. we provide explicit expressions for the mixed-state three-tangle and the corresponding optimal decompositions for this more general case. Moreover, as a special case we obtain a general solution for a family of states consisting of a generalized GHZ state and an orthogonal product state

Double Quantum Dots as Detectors of High-Frequency Quantum Noise in Mesoscopic Conductors

We propose a measurement set-up for detecting quantum noise over a wide frequency range using inelastic transitions in a tunable two-level system as a detector. The frequency-resolving detector consists of a double quantum dot which is capacitively coupled to the leads of a nearby mesoscopic conductor. The inelastic current through the double quantum dot is calculated in response to equilibrium and non-equilibrium current fluctuations in the nearby conductor, including vacuum fluctuations at very low temperatures. As a specific example, the fluctuations across a quantum point contact are discussed.Comment: 4 pages, 4 figures. Final version to appear in Physical Review Letter

Field Emission Studies of Heat Treated Mo Substrates

Molybdenum can be used as a substrate for the bi alkali antimonide photocathodes utilized for the generation of high brightness electron beams in a superconducting radio frequency SRF photoinjector cavities. Operation at high field strength is required to obtain a low emittance beam, thus increasing the probability of field emission FE from the cathode surface. Usually, substrates are heated in situ before alkali de position to remove oxide layers from the surface. FE on Mo substrates was measured by means of a field emission scanning microscope FESM . It turned out that in situ heat treatment HT of the Mo surface significantly changes the FE behaviour by activation of new emitters. For a better understanding of the mechanism for enhanced emission after in situ heating a witness Mo sample was investigated using x ray photoelectron spectroscop

Fidelity and leakage of Josephson qubits

The unit of quantum information is the qubit, a vector in a two-dimensional Hilbert space. On the other hand, quantum hardware often operates in two-dimensional subspaces of vector spaces of higher dimensionality. The presence of higher quantum states may affect the accuracy of quantum information processing. In this Letter we show how to cope with {\em quantum leakage} in devices based on small Josephson junctions. While the presence of higher charge states of the junction reduces the fidelity during gate operations we demonstrate that errors can be minimized by appropriately designing and operating the gates.Comment: 9 pages, Revtex, 2 eps figure

Hole burning in a nanomechanical resonator coupled to a Cooper pair box

We propose a scheme to create holes in the statistical distribution of excitations of a nanomechanical resonator. It employs a controllable coupling between this system and a Cooper pair box. The success probability and the fidelity are calculated and compared with those obtained in the atom-field system via distinct schemes. As an application we show how to use the hole-burning scheme to prepare (low excited) Fock states.Comment: 7 pages, 10 figure

Charge Transport Processes in a Superconducting Single-Electron Transistor Coupled to a Microstrip Transmission Line

We have investigated charge transport processes in a superconducting single-electron transistor (S-SET) fabricated in close proximity to a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The macroscopic bonding pads of the S-SET along with the 2DEG form a microstrip transmission line. We observe a variety of current-carrying cycles in the S-SET which we attribute to simultaneous tunneling of Cooper pairs and emission of photons into the microstrip. We find good agreement between these experimental results and simulations including both photon emission and photon-assisted tunneling due to the electromagnetic environment.Comment: 4 pages, 4 figures, REVTeX