Demonstration of a universal one-way quantum quadratic phase gate

We demonstrate a quadratic phase gate for one-way quantum computation in the continuous-variable regime. This canonical gate, together with phase-space displacements and Fourier rotations, completes the set of universal gates for realizing any single-mode Gaussian transformation such as arbitrary squeezing. As opposed to previous implementations of measurement-based squeezers, the current gate is fully controlled by the local oscillator phase of the homodyne detector. Verifying this controllability, we give an experimental demonstration of the principles of one-way quantum computation over continuous variables. Moreover, we can observe sub-shot-noise quadrature variances in the output states, confirming that nonclassical states are created through cluster computation.Comment: 5 pages, 4 figure

Schwarzschild radius from Monte Carlo calculation of the Wilson loop in supersymmetric matrix quantum mechanics

In the string/gauge duality it is important to understand how the space-time geometry is encoded in gauge theory observables. We address this issue in the case of the D0-brane system at finite temperature T. Based on the duality, the temporal Wilson loop operator W in gauge theory is expected to contain the information of the Schwarzschild radius R_{Sch} of the dual black hole geometry as log = R_{Sch} / (2 pi alpha' T). This translates to the power-law behavior log = 1.89 (T/lambda^{1/3})^{-3/5}, where lambda is the 't Hooft coupling constant. We calculate the Wilson loop on the gauge theory side in the strongly coupled regime by performing Monte Carlo simulation of supersymmetric matrix quantum mechanics with 16 supercharges. The results reproduce the expected power-law behavior up to a constant shift, which is explainable as alpha' corrections on the gravity side.Comment: REVTeX4, 4 pages, 1 figur

Neon isotopic composition of carbon residues from the Canyon Diablo iron meteorite

We analyzed noble gases in acid residues extracted from the Canyon Diablo iron meteorite by density and colloidal separation. The results do not indicate any significant variation among the samples although spallogenic noble gases were effectively removed by the treatment. The isotopic compositions of the heavy noble gases are close to those of the terrestrial atmosphere, suggesting that the samples were seriously contaminated by atmospheric noble gases during the treatment. However, the Ne isotopic ratios fall between atmospheric Ne and planetary Ne, suggesting that the primordial component of the noble gases in carbonaceous material in Canyon Diablo is planetary rather than solar

Evaluation of the Seismic Behavior on Sandy Ground with Built-Up Pore Water Pressures by Effective Stress Analysis

It is important to consider the non-linear behavior of the soil in evaluating the seismic behavior of the ground during the large ground motion. Pore water pressures, in the order of 75% of the initial mean confining pressures, were observed at the liquefaction observation sites near the Lake Utonai in Hokkaido, Japan during the 1993 Kushiro-oki earthquake. In the current study, effective stress analysis and total stress non-linear analysis were carried out incorporating both strain-dependent non-linearity and non-linear built-up of pore pressures. The following conclusions were reached: (1) Seismic behavior of the ground, acceleration of the surface ground, transfer functions etc., obtained from the effective analysis were sufficient to predict the observed records; (2) It was found from these analyses that shear strain was reached to 1 or 2x10-3 and pore water pressure ratio was built up to between 0.2 and 0.4 during the earthquake; (3) The amplitude and phase of the acceleration at the ground surface by effective and total stress analyses agreed well; and (4) The influence of the excess pore water pressure on the seismic behavior of the ground surface is not so significant when the excess pore water pressure ratio was less than 0.4 in general

Development of homogeneous and high-performance REBCO bulks with flexibility in shapes by the single-direction melt growth (SDMG) method

We have developed a single-direction melt growth method in which REBCO melt-textured bulks grow only vertically from a seed plate utilizing the difference in peritectic temperatures of REBCO. Entirely c-grown YBCO, DyBCO and GdBCO bulks with various sizes and shapes were successfully fabricated with high reproducibility. Disk-shaped bulks showed high trapped fields with almost concentric field distributions, reflecting homogeneous and boundaryless bulky crystal. In particular, a YBCO bulk with a 32 mm diameter trapped a high field more than 1 T at 77 K. Furthermore, rectangular and joined hexagonal REBCO bulks were successfully fabricated, showing designed field-trapping distributions reflecting their shapes through well-connected superconducting joints among bulks.Comment: 8 pages, 6 figures, 2 table

Demonstration of a quantum nondemolition sum gate

The sum gate is the canonical two-mode gate for universal quantum computation based on continuous quantum variables. It represents the natural analogue to a qubit C-NOT gate. In addition, the continuous-variable gate describes a quantum nondemolition (QND) interaction between the quadrature components of two light fields. We experimentally demonstrate a QND sum gate, employing the scheme by R. Filip, P. Marek, and U.L. Andersen [\pra {\bf 71}, 042308 (2005)], solely based on offline squeezed states, homodyne measurements, and feedforward. The results are verified by simultaneously satisfying the criteria for QND measurements in both conjugate quadratures.Comment: 4 pages, 4 figure