Higher-Dimensional Quantum Cryptography

We report on a high-speed quantum cryptography system that utilizes simultaneous entanglement in polarization and in “time-bins". With multiple degrees of freedom contributing to the secret key, we can achieve over ten bits of random entropy per detected coincidence. In addition, we collect from multiple spots o the downconversion cone to further amplify the data rate, allowing usto achieve over 10 Mbits of secure key per second.




References:
[1] Julio T. Barreiro, et. al., Phys. Rev. Lett. 95, 26051 (2005).
[2] I. Ali-Khan, C. J. Broadbent, and J. C. Howell, Phys. Rev. Lett. 98,
060503 (2007).
[3] H.-K. Lo, H. F. Chau, and M. Ardehali, J. Cryptol. 18, 133 (2005).