Cryptography relies on two communicating parties sharing a secret key. The key is used to encode all communications between the parties making it impossible for anyone to eavesdrop on the conversation. The big challenge is getting a key that is really secret. If anyone else has the key, they could intercept and decode the communication. Quantum key distribution (QKD) uses the Heiseberg uncertainty principle to ensure the distribution of a secret key. Our work is on continuous wave systems. They potentially have much higher transmission rates than single systems. Quintessence Labs is startup company that aims to commercialise this technology. Much of this work is done in collaboration with the University of Queesnland .

Publications:

Experimental demonstration of post-selection-based continuous-variable quantum key distribution in the presence of Gaussian noise.
Phys. Rev. 76 A (R), 030303 (2007)
Thomas Symul, Daniel J Alton, Syed M Assad, Andrew M Lance, Christian Weedbrook, Timothy C Ralph, Ping Koy Lam.

 

Coherent-state quantum key distribution without random basis switching
Phys. Rev. A 73, 022316 (2006)
C. Weedbrook, A. M. Lance, W. P. Bowen, T. Symul, T. C. Ralph and P. K. Lam

 

A complete quantum cryptographic system using a continuous wave laser
SPIE 6038, 03-1 (2006)
V. Sharma, A. M. Lance, T. Symul, C. Weedbrook, T. C. Ralph, and P. K. Lam

 

No-switching quantum key distribution using broadband modulated coherent light
Phys. Rev. Lett. 95, 180503 (2005)
A. M. Lance, T. Symul, V. Sharma, C. Weedbrook, T. C. Ralph and P. K. Lam

 

Quantum Cryptography Without Switching
Phys. Rev. Lett. 93, 170504 (2004)
C. Weedbrook, A. M. Lance, W. P. Bowen, T. Symul, T. C. Ralph, and P. K. Lam

Data shared between Alice and Bob in a continuous variable QKD protocol. (details here).

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Ben Buchler (email)