uncertainty principle with measurement device recoil

[Jamie M]

Hi,

I read about a modification to the uncertainty principle that takes
into account "recoil" in the measurement device, so that more
information about the system is actually available than the uncertainty
principle would predict:

http://www.nature.com/nphys/journal/v8/n3/abs/nphys2194.html

Here is another article that verified the measurement device recoil
impact on measurement uncertainty from above:

http://phys.org/news/2012-10-certainty-uncertainty-quantum-mechanical-role.html

So if the measurement device inertia is very small then it will have
more recoil so more information can be extracted? Also doesn't this
imply that entanglement is incorrect?

cheers,
Jamie

 

[Sylvia Else]

Hi,

I read about a modification to the uncertainty principle that takes
into account "recoil" in the measurement device, so that more
information about the system is actually available than the uncertainty
principle would predict:

http://www.nature.com/nphys/journal/v8/n3/abs/nphys2194.html

Here is another article that verified the measurement device recoil
impact on measurement uncertainty from above:

http://phys.org/news/2012-10-certainty-uncertainty-quantum-mechanical-role.html


So if the measurement device inertia is very small then it will have
more recoil so more information can be extracted? Also doesn't this
imply that entanglement is incorrect?

cheers,
Jamie

These experiments relate to error-disturbance relations, rather than the
fundamental uncertainty relation.

See

http://www.scientificamerican.com/article.cfm?id=heisenbergs-uncertainty-principle-is-not-dead

This is heavy-duty stuff, but my best take on it is that there is the
underlying uncertainty relation on the one hand, and on the other hand,
another relation that represents a theoretical limit on how close one
can get to the underlying relation experimentally. It is this latter
relation that is under test experimentally, and the experiments show
that the originally supposed limit was too severe, and falsified, and
that a more recent formulation of the limit remains a candidate for
being the actual limit.

But the uncertainty principle remains intact, and phase entanglement is
untouched.

Sylvia.