The ANU quantum information group have been working on many varied projects. We use lasers to create continuous variable quantum states. We then use these states to do fun things. Some of the projects we work on are listed below.
Quantum key distribution
One of the earliest application of quantum technology is quantum key distribution. By encoding information in conjugate variables of a quantum state we can detect the presence of an eavesdropper. Quantum key distribution allows for a secure information transfer even in the presence of an eavedropper.
Quantum distillation using a heralded filter
The Heisenberg uncertainty relation sets a bound on how well one can clone or amplify a quantum state. By using a heralded probabilistic filter, we can overcome this bound and obtain cloning and amplification fidelities that would otherwise violate the Heisenberg uncertainty relation.
Quantum random number generator
One of the fastest way to generate quantum random numbers is by doing homodyne measurement on the vacuum states. We operate a source of quantum random numbers in our lab. The numbers are generated from the quantum vacuum fluctuations measured using balanced homodyne detections.
We are trying to detect if an intruder is present or not. If the intruder is hiding himself in a noisy environment, how can we detect him? It turns out that by using a quantum entangled probe, the intruder can be detected with a higher probability.
How well can we measure something? After eliminating all sources of classical noise, the vacuum fluctuations will ultimately set a limit on the estimation precision. To overcome this limit, we can use non-classical states such as a squeezed or entangled state.
Squeezed state generation
A coherent state has equal uncertainty in both amplitude and phase quadratures. A squeezed state has less noise in one quadrature at the expense of more noise in the other. These states can be used to increase the phase measurement precision for example in the detection of gravity waves. They can also be used to generate entangled states and other quantum states like the cat-states.