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キーワード:
Quantum Physics, quant-ph
要旨:
We report the realization of an Einstein-Podolsky-Rosen (EPR) entanglement
source for gaussian continuous-variable quantum key distribution at 1550 nm.
Our source is based on a single continuous-wave squeezed vacuum mode with 11.1
\pm 0.1 dB squeezing, combined with vacuum at a balanced beam splitter. The
conditional variance product (Reid criterion, Phys. Rev. A 40 913, 1989) of
this source is 0.31 \pm 0.01, well below the classical threshold 1. The maximal
achievable key rate with security against collective attacks is of 0.38
bits/measurement. Although only a single squeezed beam was used, the
conditional variance product is comparable to the best reported values using
two squeezed beams.
