Physicists present a non-destructive technique for measuring at the atomic scale

May 12, 2013

Improving our understanding of the human brain, gathering insights into the origin of our universe through the detection of gravitational waves, or optimizing the precision of GPS systems- all are difficult challenges to master because they require the ability to visualize highly fragile elements, which can be terminally damaged by any attempt to observe them. Now, quantum physics has provided a solution. In an article published in Nature Photonics, researchers at the Institute of Photonic Sciences (ICFO) report the observation of a highly fragile and volatile body through a new quantum-mechanical measurement technique.

Researchers from the group led by Morgan Mitchell applied the so-called "quantum non-demolition measurement" to a tiny cloud of atoms. They were able to observe the spinning of the electrons in the atoms, and more importantly, the atom cloud was not disturbed in the process. It is the first time quantum non-demolition measurement has been demonstrated with any material object. The same method could be extended to permit the observation of individual atoms.

In the experiment, scientists prepared with photons in complementary states, and then sent them through the cloud of atoms, measuring their polarization on the way out. "A first measurement gives us information reflecting the action of the first light pulse. A second measurement, taken with photons in a complementary state from the first, cancels the influence of the preliminary pulse, allowing us to observe the original characteristics of the object," explains Dr. Robert Sewell, researcher at ICFO. This process has enabled the team to gather precise information on the magnetic field of the atom's surroundings.

The information obtained exceeds the so-called "standard ", which quantifies the maximum amount of information obtainable with any traditional probing. Two achievements made this possible. On one hand, researchers were able to structure the observation so that the noise resulting from the visualization was shifted away from the object being measured and into a different variable. In addition, they introduced quantum statistical correlations among the atoms so that they were able to gather in one measurement what previously they needed a collection of measurements to observe. "This experiment provides rigorous proof of the effectiveness of for measuring delicate objects" concludes Sewell.

Explore further: Viewing deeper into the quantum world

More information: Certified quantum non-demolition measurement of a macroscopic material system, DOI: 10.1038/nphoton.2013.100

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EyeNStein
2.6 / 5 (5) May 05, 2013
'quantum non-demolition measurement '
Tap the atoms with a small wrecking ball, then tap them back into place again with an anti-wrecking ball.
This can only happen in the quantum world!

The potential for this measurement / anti-measurement technique is quite high as it 'exceeds the quantum limit' for information you are normally allowed to obtain from a system without destroying it. You might even be able intercept secure quantum communications if this technique can be extended to photons.
vacuum-mechanics
1 / 5 (5) May 05, 2013
Researchers from the group led by Morgan Mitchell applied the so-called "quantum non-demolition measurement" to a tiny cloud of atoms. They were able to observe the spinning of the electrons in the atoms, and more importantly, the atom cloud was not disturbed in the process. It is the first time quantum non-demolition measurement has been demonstrated with any material object. The same method could be extended to permit the observation of individual atoms.

This seems to be another advance technology which tries to solve the measurement problem in quantum ream; anyway the real solution to the problem should come after we understand how the quantum measurement mechanism works as follow.
http://www.vacuum...19〈=en
LarryD
not rated yet May 05, 2013
Agreed is another step in the right direction but wouldn't the initial view of the 'atom cloud' disturb it also. Or maybe I have misunderstood...is the initial observation the first 'knock' on the cloud also?
EyeNStein
1.8 / 5 (5) May 06, 2013
Their point is that by doing a very specific type of measurement you know exactly how you disturbed the system to get the atom-state information out. By then doing the opposite anti-phase measurement you put the system back as it was. (Give or take any artefacts left behind by measurement features you couldn't anti-phase and do 'backwards'.)
dan42day
not rated yet May 07, 2013
Great, now scan my brain and make a backup. Once we figure out how to load the backup into my clone, I should be good for another 60 years or better. Of course it will take a great leap of faith that once the clone is up and running, my present body can be destroyed without losing the continuity of my life.

Any thoughts?

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