Continuous Variable Quantum Encryption using Short Laser Pulses

The use of optical technology in communication links has compelling advantages in terms of data rate, power consumption, weight, and size of the system. However, with the adoption of such technology, we have become heavily reliant on optical communication systems for our economy and national security. It is thus prudent to give careful consideration to the reliability, robustness to attack, and security of such data transmissions. Recently, a new method to protect the secrecy of optical transmissions against unauthorized eavesdropping has been proposed and demonstrated. This method, called AlphaEta, uses the quantum noise inherent in the light to create a highly secure physical layer encryption system which performs comparably, in terms of metrics such as propagation distance and sensitivity, to a conventional system. We propose to augment an AlphaEta-like system by using a short pulse source to add the capability for spectral phase encoding, which increases the security due to increasing the inherent random quantum noise, increasing the encryption complexity, and forcing wide-band measurements (~1THz) on an attacker. These properties augment the security of encryption, and when paired with traditional key generation algorithms can substantially increase key generation security without the severe performance degradation associated with quantum key distribution.