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 coloured square The University of Melbourne School of Physics - Optics Group

2007 Atom optics honours projects

Here are a few more words about some of the possible projects in the atom optics lab. Expect to have lots of fun, while you learn about quantum mechanics, lasers, electronics, optics, computer modelling, and data analysis and visualisation.

Squeezing

Classical measurements with light are limited by Poissonian uncertainty; that is, to measure, say, 100 photons, inevitably there is an uncertainty of +/- Sqrt[100], i.e. 10%. Light can be "squeezed" such that this uncertainty is reduced. Quantum noise limits can be much lower, but strong squeezing is notoriously difficult. Recently a new and very simple technique has been demonstrated using laser interaction with atomic vapour. In this project, we will demonstrate the method, and try a new idea which promises squeezing with very low laser power.

Non-interferometric phase imaging

Electromagnetic waves are traditionally described by an amplitude and a phase. Imaging typically uses the amplitude (or intensity), but phase imaging can offer advantages. For example, absorption (amplitude) imaging of ultra-cold atoms inherently causes heating; off-resonant phase imaging can be much less destructive.

We have developed new phase-imaging techniques based on diffraction of a laser beam by a sample of cold atoms. The intensity of the diffracted probe beam is recorded with a CCD camera, and using our understanding of diffraction and of light-atom interactions, we can extract an image of the atomic cloud.

The method allows us to investigate the atomic state, in particular to image quantum superpositions of states such as used for "slow light" and "electromagnetically induced transparency". In this project we will investigate phase shifts in slow-light configurations.

Ultracold plasma

Plasma is normally hot, because separation of electrons from atoms requires lots of energy. It is possible (in fact, quite easy) to photo-ionise atoms with a laser tuned to just the right energy to remove the electron. If the atom is initially very cold, then the ion+electron will remain cold. Thus by photo-ionising a cloud of cold atoms - atoms at a temperature of a few hundred micro-Kelvin - we can produce an ultra-cold plasma.

Such plasmas are an exciting new playground for all kinds of interesting physics, and also directly applicable as the source of ultrabright electrons. We are working towards creating an ultrabright electron source, which will later become the basis of a new compact x-ray source.

Rydberg atoms

FAT atoms: Making really big "Rydberg" atoms, in a highly excited but not quite ionised state, such that the outer electron orbital is as big as a micron in diameter.

Ghost imaging

Action at a distance, using correlated and entangled photons to image an object that isn't there.

Atomic clocks

New schemes of locking lasers to coherent quantum states in atoms, with precision measured in seconds per hundred-thousand-years.
Created: 9 August 2006
Last modified:
Authorised by: A/Prof R Scholten, School of Physics
Maintained by: A/Prof R Scholten, School of Physics