Observation of -9 dB quadrature squeezing with improvement of phase stability in homodyne measurement

We observe -9.01$\pm$0.14 dB of squeezing and +15.12$\pm$0.14 dB of antisqueezing with a local oscillator phase locked in homodyne measurement. In reference [1], two main factors are pointed out which degrade the observed squeezing level: phase fluctuation in homodyne measurement and intracavity losses of an optical parametric oscillator for squeezing. We have improved the phase stability of homodyne measurement and have reduced the intracavity losses. We measure pump power dependences of the squeezing and antisqueezing levels, which show good agreement with theoretical calculations taking account of the phase fluctuation.Comment: 4 pages, 4 figure

High-fidelity teleportation beyond the no-cloning limit and entanglement swapping for continuous variables

We experimentally demonstrate continuous-variable quantum teleportation beyond the no-cloning limit. We teleport a coherent state and achieve the fidelity of 0.70$\pm$0.02 that surpasses the no-cloning limit of 2/3. Surpassing the limit is necessary to transfer the nonclassicality of an input quantum state. By using our high-fidelity teleporter, we demonstrate entanglement swapping, namely teleportation of quantum entanglement, as an example of transfer of nonclassicality.Comment: revised version, 4 pages, 4 figure

Sequential Quantum Teleportation of Optical Coherent States

We demonstrate a sequence of two quantum teleportations of optical coherent states, combining two high-fidelity teleporters for continuous variables. In our experiment, the individual teleportation fidelities are evaluated as F_1 = 0.70 \pm 0.02 and F_2 = 0.75 \pm 0.02, while the fidelity between the input and the sequentially teleported states is determined as F^{(2)} = 0.57 \pm 0.02. This still exceeds the optimal fidelity of one half for classical teleportation of arbitrary coherent states and almost attains the value of the first (unsequential) quantum teleportation experiment with optical coherent states.Comment: 5page, 4figure

A Research on School Principals’ Recognition of Current Situations and Issues in Regard to the Promotion of ICT Use at Schools

　本稿の目的は，校長を対象とした調査研究を通じて，教育の情報化の現状と課題に関する校長の認識を把握し，教育の情報化の推進に寄与しうる基礎的知見を得ることである。そのために，具体的には以下の点について検討した。① ICT の利用に関する現任校や自身の現状に対する校長の認識，②学校全体としてICT の活用を進めていくための改善の必要性に対する校長の認識，③ ICT の利用に関する現状認識の差異による改善の必要性に関する認識の差異，④教育の情報化を進めたり，ICT を活用したりするなかで，当初予想していなかった成果・効果，⑤教育の情報化を進めたり，ICT を活用したりするなかで，当初予想していなかった課題・問題