Quantum Communication

Quantum Repeater

In conventional optical communication, information carrying light pulses can travel in near transparent optical fibres for hundreds of kilometres. In order to extend the communication range of optical telecommunication networks for global usage, optical amplifiers are used to amplify the light signals along the length of the communication line. These amplifier stations, also known as “repeater stations”, can be located along highways, under the ocean, or within an earth orbiting satellite in space.

Quantum Memory

Large scale implementations of quantum information processing technology will require a quantum memory. The process of measurement collapses a quantum state. To build a quantum memory, therefore, you need to devise a system where you can never know the state you are storing. In our experiments we store optical quantum states by mapping the light into atomic ensembles. We can reverse this mapping and recall stored light on demand. The process pioneered by groups in this centre is known as a the Gradient Echo Memory (GEM) and can work with ensembles of both two and three level atoms.

Secure Quantum Communications

The Secure Quantum Communication program of the Centre for Quantum Computation & Communication Technology aims at building Australia’s first Quantum Key Distribution Network. A Quantum Key Distribution apparatus is a device that enables two distant parties to generate a common random cryptographic key, the uniqueness and security of which is insured by the laws of quantum mechanics rather than mathematical assumptions. The program spans the different aspects of such a network, encompassing the optical and electronic physical implementation, the reconciliation, privacy amplification and other processing of the data streams, as well as the experimental modeling and theoretical proofs of security.