Looking over experimental equipment at the University of
Otago Light and Matter Laboratory are (from left) physicist
Dr Niels Kjaergaard, physics student Kris Roberts and
postdoctoral fellow Dr Amita Deb. Photo by Gregor
Two University of Otago physics students have pushed the
frontiers of quantum technology by helping develop
laser-operated ''optical tweezers'' that precisely split clouds
of ultracold atoms and smash them together.
Kris Roberts and Thomas McKellar have added significantly to
cutting-edge research on ultracold atoms, which interact at
temperatures of less than a millionth of a degree above
Absolute zero is about minus 273.15C.
Danish-born Otago lead researcher and physicist Dr Niels
Kjaergaard said there were many potential applications from
the new research.
These included developing tools for probing microscopic
structures and sensors that could map minute variations in
In 1998, Otago physicists became the first scientists in the
southern hemisphere to create a novel state of matter - known
as Bose-Einstein Condensate - in which thousands of atoms
enter a quantum state and often behave as if they were a
This state of matter was predicted in 1925 but was created
for the first time by US researchers only in 1995.
Scientists at the Jack Dodd Centre for Quantum Technology
at the Otago physics department have, over the years, made many
novel international research findings involving ultracold
Dr Kjaergaard was ''very proud'' of the ''notable
achievements'' of Mr Roberts, who developed a novel steerable
optical tweezers unit as part of his BSc (Hons) work and Mr
McKellar, an MSc student, who built a related control unit.
Both students are now part of Dr Kjaergaard's research group.
Mr Roberts was yesterday still coming to terms with the fact
he was now the lead author of a scientific paper on the new
cutting-edge system, which was published yesterday in the
United States journal Optics Letters.
Scientists said Mr McKellar had developed his control unit
using some improvised equipment valued about $700, which
nevertheless proved effective.
The Otago researchers used their new approach to split a
''single ultracold cloud of rubidium atoms sequentially into
32 daughter clouds, spreading them out over nearly half a
This kind of precise control was ''like being able to pull a
delicate snowflake into two clean halves with your bare
hands'', Dr Kjaergaard said.
The research was supported by a Marsden Fund grant.