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OPTICAL SPECTROSCOPY OF QUANTUM DEVICES

 

Program Manager:
Prof Halina Rubinsztein-Dunlop - University of Queensland

Participating UQ Researchers:
Dr Mark Fernee
A/Prof Norman Heckenberg
Mr Jamie Warner
Mr Alexis Bishop

Collaborating Centre Researchers:
Prof Robert Clark - University of New South Wales
A/Prof Steven Prawer - University of Melbourne
Dr Ian Gentle, Chemistry Dept - University of Queensland
Dr Matt Trau, Chemistry Dept - University of Queensland

Program Description:

Coherence and coupling in Semiconductor quantum dots

Quantum dots are quantum confined structures where electrons (and holes) "feel" the effects of containment in a nanometre sized structure. Therefore, according to the laws of quantum mechanics, the energy levels of such systems are determined by the size of the quantum dot.

In a semiconductor, under conditions of strong confinement, the conduction and valence bands shift further apart and split into discreet energy states, approximating what is often referred to as an "artificial atom". These quantum dots have been shown to display significantly modified semiconductor properties such as reduced coupling to phonons and enhanced nonlinearity. Different excitonic states of a quantum dot may be used as qubit states in a quantum gate made by coupling individual quantum dots.

The effect of decoherence in such systems can be readily probed using laser systems which are themselves highly coherent.

Present and future direction for the Quantum Device Modelling Group

  • Preparation of new colloidal PbS quantum dots for use in single and coupled dot detection

  • Detection of individual and coupled quantum dots using an etched near-field nano-mask

  • Using quantum dots to model the J-gate interaction of the Kane quantum computer

  • Encoding and transfer of information via electron spin in quantum dots

  • Study of charged quantum dots and the realization of optically accessible quantum dot atoms

  • Investigation of decoherence of electronic donor levels in solid-state systems (eg. P donors in Si)

  • Optical interactions with electronic donor levels in solid-state system

 

Fluorescence activated PbS quantum dots.   A diagram of nano-mask near-field microscopy used for the detection of single and coupled quantum dots. The use of near-field excitation gives enhanced resolution and strong laser light rejection
   
Fluorescence activated PbS quantum dots. (The red sample is mainly band-edge fluorescene. The orange sample displays strong above-band-edge fluorescence.   A diagram of nano-mask near-field microscopy used for the detection of single and coupled quantum dots. The use of near-field excitation gives enhanced resolution and strong laser light rejection.

 

 


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