Yet another story of great Australian minds at work!
Why we don’t have a flourishing commercial science & technology industry in this country is beyond me!
Maybe it has something to do with our governments/taxes/regulations/red tape/hopeless bureaucrats?
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http://www.abc.net.au/science/articles/2013/02/04/3681478.htm
Stephen Pincock
ABC
For the first time, Australian scientists have explored the inner workings of a living cell using a new kind of laser microscopy that harnesses the laws of quantum physics.
The technique could shed light on new biological processes, the motion of microscopic particles, and even allow quantum mechanics to be studied at a scale visible to the naked eye, says the study’s lead author, physicist Dr Warwick Bowen from the University of Queensland.
When scientists want to study the miniscule goings-on within a living cell, they come up against a limit known as “quantum shot noise,” Bowen and colleagues explain in the latest issue of the journal Nature Photonics.
This phenomenon is a result of the fact that light particles, or photons, hit the microscope’s detection device randomly.
“You can get the idea if you imagine the photons are raindrops falling on a square of ground, and you were to count the number hitting the ground in a given time interval,” Bowen explains. “Obviously, there’ll be some randomness in the number hitting the ground in a given time – this is shot noise.”
To study biological systems such as cells, scientists aim to detect very small levels of scattered light from an object within the biological specimen. Because the level of scattering from these tiny objects is so small, it can easily be obscured by shot noise.
“You can solve this by increasing your laser power,” says Bowen. “Then, since you’re measuring more photons per time interval, the error in your measurement improves. However, in living systems you simply cannot keep increasing the optical power – very soon you fry the cell.”
The team of researchers from the University of Queensland and the Australian National University overcame this problem by “quantum correlating” photons, a phenomenon also known as entanglement. In effect, this allows them to control the photons so they hit the detector in bunches with a well defined number. This is the first time this has been shown to work in a biological sample, Bowen says.
Squeezing light
To generate their quantum-correlated light, the researchers used a process called optical parametric oscillation. They took single photons, and “broke” them into pairs of photons, each with half the energy of the original photon.
The quantum correlations also allowed the researchers to “squeeze” the fluctuations of the amplitude of the light by 75 per cent. “This should allow, in principle, a factor of four improvement in sensitivity in our measurements. However some imperfections in the measurements themselves meant that we achieved only a factor of two or so improvement,” Bowen says.
The technique is technically challenging, and at this stage it is unclear how important it will be, he notes.
“If there turns out to be important biological processes occurring that cannot be observed without quantum correlations, then the technique could be very important to understand those processes. We don’t know the answer to this yet – it remains to be discovered.”
“We do know that the technique could be very helpful in observing phenomena in the microscopic motion of small particles that have yet to be observed and were predicted many decades ago.”
“We also know that this technique could be important for studying truly fundamental physics – where the quantum correlations between photons could be transferred onto particles consisting of 10^16 atoms or so.”
“This would push the theory of quantum mechanics out of the microscopic world and into massive objects that you can see by eye – testing the theory in a regime never before accessed.
“Many groups in the world are trying to achieve this goal but I can’t emphasis enough how challenging it is.”