Photon-bunching measurement after two 25-km-long optical fibers

被引:39
作者
Halder, M [1 ]
Tanzilli, S [1 ]
de Riedmatten, H [1 ]
Beveratos, A [1 ]
Zbinden, H [1 ]
Gisin, N [1 ]
机构
[1] Univ Geneva, Appl Phys Grp, CH-1211 Geneva, Switzerland
来源
PHYSICAL REVIEW A | 2005年 / 71卷 / 04期
关键词
D O I
10.1103/PhysRevA.71.042335
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
To show the feasibility of a long-distance partial Bell-state measurement, a Hong-Ou-Mandel experiment with coherent photons is reported. Pairs of degenerate photons at telecommunication wavelength are created by parametric down-conversion in a periodically poled lithium niobate waveguide. The photon pairs are separated in a beam splitter and transmitted via two fibers of 25 km. The wave packets are relatively delayed and recombined on a second beam splitter, forming a large Mach-Zehnder interferometer. Coincidence counts between the photons at the two output modes are registered. The main challenge consists in the trade-off between low count rates due to narrow filtering and length fluctuations of the 25-km-long arms during the measurement. For balanced paths a Hong-Ou-Mandel dip with a net visibility of 47.3% is observed, which is close to the maximal theoretical value of 50% developed here. This proves the practicability of a long-distance Bell-state measurement with two independent sources, as, e.g., required in an entanglement swapping configuration in the scale of tens of kilometers.
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页数:5
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