The ANU quantum information group have been working on many varied projects. We are a small experimental group led by Syed Assad and Ping Koy Lam. Mostly, we use lasers to create continuous variable quantum states. We then use these states to do fun things. Sometimes, we do random things—like thinking about what we can do if we have a time-machine. This kind of things tend to happen when Mile and Jayne come visit. We also have close collaborations with Tim Ralph from the university of Queensland, 李小英 from Tianjin University and our spin-off company QuintessenceLabs.
We're always looking for motivated and talented people to join our group. If you're interested to join us, please contact our boss: Ping Koy Lam. Some available student projects are listed on the RSPE website.
For more information on what we do, click on the headers below.
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.
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.
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.
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.