High-fidelity transmission of polarization encoded qubits from an entangled source over 100 km of fiber

Abstract

We demonstrate non-degenerate down-conversion at 810 and 1550 nm for long-distance fiber based quantum communication using polarization entangled photon pairs. Measurements of the two-photon visibility, without dark count subtraction, have shown that the quantum correlations (raw visibility 89%) allow secure quantum cryptography after 100 km of non-zero dispersion shifted fiber using commercially available single photon detectors. In addition, quantum state tomography has revealed little degradation of state negativity, decreasing from 0.99 at the source to 0.93 after 100 km, indicating minimal loss in fidelity during the transmission.

arXiv comment7 pages, 4 figures

References in corpus (13)

• Quantum Cryptography
• A computable measure of entanglement
• On the Measurement of Qubits
• Security against individual attacks for realistic quantum key distribution
• Quantum state estimation
• Distribution of time-bin qubits over 50 km of optical fiber
• Security of Quantum Key Distribution with Entangled Photons Against Individual Attacks
• Entanglement of remote atomic qubits
• Practical Quantum Key Distribution with Polarization-Entangled Photons
• Long distance entanglement based quantum key distribution
• Efficient and spectrally bright source of polarization-entangled photons
• Long-distance distribution of time-bin entanglement generated in a cooled fiber
• Theory and experiment of entanglement in a quasi-phase-matched two-crystal source