60 research outputs found
Experimental demonstration of quantum teleportation of a squeezed state
We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe -0.8 ± 0.2dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of broadband entanglement. Our teleporter achieves sufficiently high fidelity to allow the teleportation to be cascaded, enabling, in principle, the construction of deterministic non-Gaussian operations
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 0.700.02 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
Observation of -9 dB quadrature squeezing with improvement of phase stability in homodyne measurement
We observe -9.010.14 dB of squeezing and +15.120.14 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
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
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