Experiment makes Schrodinger's cat choose

#1
—things can be real, or certain, but not both
Experimenting within quantum theory is an extremely complex process, where common intuitions are regularly inverted within shifting reality. Over the years several quantum features and methods of their study have been identified. Now scientists have investigated a new set of assumptions and proposed a novel experiment, to test the consequences of making quantum theory more intuitive.

"While quantum theory is the science behind almost all of our technology, its disconnect with our everyday intuitions is still worrisome and actively researched," says lead author Associate Professor Daniel Terno.

"How do you find your way in a reality which is shifting, where the opposites are allowed to coexist? Moreover, how do you conduct experiments in it? These are the questions that must be answered when dealing with the floating world of quantum mechanics."

Throughout the development of quantum theory, a set of reasonable ideas has led to strange paradoxes, such as the famous Schrodinger's cat, which is neither dead nor alive.

Another of the most famous (and useful) results of quantum mechanics is that every objects can behave as a particle or as a wave, given the right conditions. Associate Professor Terno and colleagues proposed a new experiment in 2011, which was realised by dozens of research groups worldwide. This proposal made complicated experiments much simpler, such as an experiment formerly requiring 40 meters of optical cable now being performed on just a single chip.

Using this wave-particle duality as their starting point, the research team investigated a new and more comprehensible set of assumptions:

  1. Every object at any time is really a particle or a wave, but not both (objectivity)
  2. If you know enough you can predict everything (determinism)
  3. Speed of light is the ultimate limit (locality)
In taking these assumptions and applying them to an experiment, where the measuring device is controlled by a Schrodinger's cat-like state, the research team reached some perplexing paradoxes.

"Only after the cat was found to be dead or alive were we able to tell if what we did was to look for a particle or for a wave," says Associate Professor Terno. "Then these three innocent-looking ideas result in predictions that would contradict an experiment. The universe simply does not work like that: you can see things to be real, or certain, but not both."

Then the researchers tweaked their initial assumptions, replacing the third assumption with the requirement that how you set your detectors does not affect the system you study before they interact. This tweak lead to another strange result: it is not only that our quantum world is not like that, but such a combination cannot be realized in any universe.

"We can just repeat after Alice: things get curiouser and curiouser."



Read more at: http://phys.org/news/2014-09-schrodinger-cat-choosethings-real.html#jCp
 
#2
As someone who visits phys.org almost daily, I find the things you're choosing to post here to be amusing. So far they all are predicated on what I said before - "attempts to have things make more sense to standard thinking." The interesting thing that the researchers here are willing to ignore is that applied in macro QM also suggest that their conclusions themselves can be true, not true or both. ;)
 
#5
Here's the update with a bit more clarity.
http://phys.org/news/2014-07-entanglement-particle-wave-like-states-resembles.html#inlRlv

Rather than being dead and alive, however, the states correspond to the long and short arms of the interferometer through which each photon travels. It's as if a photon traveled through both arms at the same time. By performing a procedure that erases the information regarding which arm the photons travelled through, the physicists could entangle a photon with a wave-like state that they call a photon-added coherent state.
Because the new state is essentially a superposition including both particle and wave components, it can be viewed as a new type of qubit. Usually, a qubit consists of a particle that is in a superposition of two quantum states. The new idea here is that a qubit can consist of a quantum (or particle-like) state and a classical (or wave-like) one, which could effectively combine the intrinsic advantages of both. In this way, a hybrid qubit could offer unique advantages for quantum computing and quantum teleportation.
 
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#6
It's as if a photon traveled through both arms at the same time. By performing a procedure that erases the information regarding which arm the photons travelled through, the physicists could entangle a photon with a wave-like state that they call a photon-added coherent state.

That's the most interesting I think. Such a strange thing, it really is about information. As soon as that information is known it becomes manifest and part of this reality. Real but uncertain or certain and unreal ? Information is more fundamental than matter.
 
#9
Perhaps because there's a chance we get fully objective realism and determinism back? The uncomfortable results of QM can be pushed aside.
I can't get at the paper, so don't really understand what they did. The article mentions that every object can behave as a particle or a wave. That had my alarm bells ringing. The author is also quoted as indicating that QM is 'worrisome'?

On the other hand 'real' could be interpreted as spatial, and 'certain' interpreted as temporal. That one can only know one or the other, but not both doesn't seem that spectacular... in my opinion it sounds rather like Heisenberg's Principle of Uncertainty. So without reading the paper I dunno really what it's significance is.

As for why Steve posted it, who knows...? He doesn't explain why he finds it interesting.
 
#10
I can't get at the paper, so don't really understand what they did. The article mentions that every object can behave as a particle or a wave. That had my alarm bells ringing. The author is also quoted as indicating that QM is 'worrisome'?

On the other hand 'real' could be interpreted as spatial, and 'certain' interpreted as temporal. That one can only know one or the other, but not both doesn't seem that spectacular... in my opinion it sounds rather like Heisenberg's Principle of Uncertainty. So without reading the paper I dunno really what it's significance is.

As for why Steve posted it, who knows...? He doesn't explain why he finds it interesting.
The bold sends something ringing too. QM is in the words of Rosenblum and Kutner, "the most battle tested theory in science...no prediction has shown to be wrong". Of course QM is worrisome, it violates a lot of out intuition, yet it is very well tested and established.
 
#12
I'm guessing it's only worrisome to those who keep trying to understand it using classical physics.
I somehow don't think we can understand it using classical physics. Our favourite physicist Anton Zeilinger says the following about QM: "this new theory (referring to something beyond current quantum theory) will be so much stranger...people attacking quantum mechanics now will long to have it back"
 
#13
I somehow don't think we can understand it using classical physics.
Yes, recently I've become much more aware of physicists (QM and otherwise) who seem to incorporate incompatible ideas into their explanation of QM, things like 'weak measurement', and attempting to measure what is going on during the experiment before we measure, lol, and literal belief that there really is some sort of wave... etc...

I don't understand the maths of QM at all, but I sometimes feel I actually understand and therefore accept the basic overall concepts of QM better than many of the experts... which is an odd thought... Perhaps I just have an odd brain, or perhaps I'm just deluding myself. :)

Sometimes it feels that there is a massive hidden fight going on between QM and Classical Physics... It is over the top for me to say, but Classical Physics died early in the 20th Century, it was a useful approximation, but it's not how nature actually appears to work, and it feels like QM is constantly under attack from those who want classical physics back.
 
#14
Yes, recently I've become much more aware of physicists (QM and otherwise) who seem to incorporate incompatible ideas into their explanation of QM, things like 'weak measurement', and attempting to measure what is going on during the experiment before we measure, lol, and literal belief that there really is some sort of wave... etc...

I don't understand the maths of QM at all, but I sometimes feel I actually understand and therefore accept the basic overall concepts of QM better than many of the experts... which is an odd thought... Perhaps I just have an odd brain, or perhaps I'm just deluding myself. :)

Sometimes it feels that there is a massive hidden fight going on between QM and Classical Physics... It is over the top for me to say, but Classical Physics died early in the 20th Century, it was a useful approximation, but it's not how nature actually appears to work, and it feels like QM is constantly under attack from those who want classical physics back.
But it's deeply uncomfortable for people. That's why as I'm sure you agree. Zeilinger's comment "we are not just passive observers" makes many people balk at the very notion that measurement somehow effects reality. Secondly, classical physics makes things simple and easy to understand. We humans do not like uncertainty and the unknown, so imho, QM blasts away the known, and forces us to confront the startling notion than reality is not all that it seems
 
#16
As someone who visits phys.org almost daily, I find the things you're choosing to post here to be amusing. So far they all are predicated on what I said before - "attempts to have things make more sense to standard thinking." The interesting thing that the researchers here are willing to ignore is that applied in macro QM also suggest that their conclusions themselves can be true, not true or both. ;)
I give you this my good man: http://arxiv.org/pdf/1310.8343v1.pdf
 
#17
Thanks. It helps reinforce my point. ;;/?
is often perceived as a philosophical challenge to our concepts of reality, locality or space-time since it contrasts our intuitive expectations with experimental observations on isolated quantum systems
That spells it out. Apart from the misuse of "intuition" to mean "habituated" and/or "what one thinks should happen".
 
#19
One of the posters on physics forums stated that if we could isolate an asteroid enough we could place it into quantum superposition.
lol. Interesting thought. What comes to mind is an episode of SG-1. They engage hyperspace just before crashing into Earth which in essence puts Earth into a QS-like state so they pass through it.
 
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