Research team challenges the limits of famous quantum principle

Phys dot org ^ | February 05, 2014 | University of Queensland

[SunkenCiv]

Almost a century ago, renowned quantum theorist Werner Heisenberg found fundamental limits on how well a quantum system can be prepared and measured, known as Heisenberg's uncertainty principle.

However, only the limit that pertains to the preparation of quantum systems has been quantified; the other two, relating to measurements, have long been a matter of debate, lacking a formal treatment.

These limits are: That it is impossible to jointly measure incompatible quantities, for instance, location and speed of a quantum object, with perfect accuracy; and that a measurement of one of these quantities necessarily disturbs the other.

Last year, UQ's Cyril Branciard proposed a new set of "uncertainty relations", for the joint measurement of incompatible quantities, which describe the minimal disturbance that will occur for a given measurement accuracy.

"Branciard's relations quantify how accurately we can measure," Mr Ringbauer said.

"Testing these relations, we are now able to show in the lab that we can actually reach this ultimate limit of accuracy," he said.

The study was published in January in the journal Physical Review Letters. A related work by Kaneda et al. in the same journal, has found similar results.

[SunkenCiv]

Heisenberg’s uncertainty limits how sharp measurements can be performed on quantum systems. UQ researchers have now performed joint measurements of single photons, challenging the limits of quantum theory. Credit: Martin Ringbauer

[SunkenCiv]

Physicists scoop information from Schrodinger’s cat box [Quantum Mechanics]
Christian Science Monitor | January 21, 2014 | Eoin O’Carroll
Posted on 1/22/2014 5:53:50 PM by ETL
http://www.freerepublic.com/focus/chat/3114541/posts

[SunkenCiv]

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[gusopol3]

Apparently, there is enough uncertainty in measuring the diameter of a proton , about a factor of five. Maybe we shouldn’t ooh and ahh so much. Especially when scientists, for whom I have great respect, weaponize their prestige to influence public perception and debate in untestable and even unknowable areas.

[Talisker]

All scientific knowledge is nothing BUT defining statistical measurement thresholds.

In this case however, it seems that they’re addressing the issue of even HAVING a statistical measurement threshold, not refining it.

So I guess that counts as a discovery!

[bigbob]

I would reply to this thread but the act of doing so would alter what I was going to say

[gorush]

[mikrofon]

"Testing these relations, we are now able to show in the lab that we can actually reach this ultimate limit of accuracy," he said.

OK, but how certain are they of their findings ??

[Usagi_yo]

My cat died.

[faithhopecharity]

Article speaks of “incompatible” quantities whereas Heisenberg spoke of conjugate quantities ( like position and momentum). ——?