QKD experiment uses entangled photon pairs

June 1, 2007
Although entangled-photon pairs have been generated in the 1550 nm telecommunications band within optical fiber for research into secure quantum-key distribution (QKD), previous experiments have only estimated the quantum bit-error rate (QBER) and sifted-key generation rate from prestage results.

Although entangled-photon pairs have been generated in the 1550 nm telecommunications band within optical fiber for research into secure quantum-key distribution (QKD), previous experiments have only estimated the quantum bit-error rate (QBER) and sifted-key generation rate from prestage results. But now, sifted keys-defined as keys created after reconciliation of the measurement basis-have been generated for the first time in an entanglement-based differential-phase QKD experiment by researchers at NTT (Atsugi, Japan) and Osaka University (Osaka, Japan).

Light from an external-cavity semiconductor laser at 1551.11 nm is converted into a pulse stream by a lithium niobate modulator followed by an erbium-doped fiber amplifier and launched into a cooled 500 m length of dispersion-shifted fiber with 1551 nm zero-dispersion wavelength. Spontaneous four-wave mixing produces a series of time-correlated entangled-photon pairs that are then actively phase-modulated by a lithium niobate modulator followed by a planar-lightwave-circuit Mach-Zehnder interferometer. Sifted keys with a length of 133 bits were generated, and the QBER was measured at 8.3% with a key generation rate of 0.3 bit/s, good enough to be distilled to a secure key through error correction and privacy amplification. Contact Toshimori Honjo at [email protected].

Sponsored Recommendations

March 31, 2025
Enhance your remote sensing capabilities with Chroma's precision-engineered optical filters, designed for applications such as environmental monitoring, geospatial mapping, and...
March 31, 2025
Designed for compatibility with a wide range of systems, Chroma's UV filters are engineered to feature high transmission, superior out-of-band blocking, steep edge transitions...
March 31, 2025
Discover strategies to balance component performance and system design, reducing development time and costs while maximizing efficiency.
March 31, 2025
Explore the essential role of optical filters in enhancing Raman spectroscopy measurements including the various filter types and their applications in improving signal-to-noise...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!