Spooky Physics --"Quantum Mechanics can Mimic an Influence of Future Actions on Past Events"

 

                          

Physicists at the Institute for Quantum Optics and Quantum Information, the University of Vienna, and the Vienna Center for Quantum Science and Technology have demonstrated in an experiment that the decision whether two particles were in an entangled or in a separable quantum state can be made even after these particles have been measured and may no longer exist. 

According to the Austrian physicist Erwin Schrödinger, entanglement is the characteristic trait of quantum mechanics. In addition to its crucial role for the foundations of physics, entanglement is also a key resource for upcoming quantum information technologies such as quantum cryptography and quantum computation. Entangled particles exhibit correlations which are stronger and more intricate than those allowed by the laws of classical physics. 

If two particles are in an entangled quantum state, they have perfectly defined joint properties at the expense of losing their individual properties. This is like having two dice which have no orientation until they are subject to measurement, upon which they certainly show the same (random) side up. 

In contrast, so-called separable quantum states allow for a classical description, because every particle has well-defined properties on its own. Two dice, each one of them with its own well-defined orientation, are in a separable state. Now, one would think that at least the nature of the quantum state must be an objective fact of reality. Either the dice are entangled or not. Zeilinger's team has now demonstrated in an experiment that this is not always the case.

The authors experimentally realized a "Gedankenexperiment" called "delayed-choice entanglement swapping", formulated by Asher Peres in the year 2000. Two pairs of entangled photons are produced, and one photon from each pair is sent to a party called Victor. Of the two remaining photons, one photon is sent to the party Alice and one is sent to the party Bob. Victor can now choose between two kinds of measurements. If he decides to measure his two photons in a way such that they are forced to be in an entangled state, then also Alice's and Bob's photon pair becomes entangled. If Victor chooses to measure his particles individually, Alice's and Bob's photon pair ends up in a separable state. 

Modern quantum optics technology allowed the team to delay Victor's choice and measurement with respect to the measurements which Alice and Bob perform on their photons. 

"We found that whether Alice's and Bob's photons are entangled and show quantum correlations or are separable and show classical correlations can be decided after they have been measured", explains Xiao-song Ma, lead author of the study.

According to the famous words of Albert Einstein, the effects of quantum entanglement appear as "spooky action at a distance". The recent experiment has gone one remarkable step further.

"Within a naïve classical word view, quantum mechanics can even mimic an influence of future actions on past events", says Anton Zeilinger at the Institute for Quantum Optics and Quantum Information, the University of Vienna

The results will be published this week in the journal Nature Physics: Experimental delayed-choice entanglement swapping: Xiao-song Ma, Stefan Zotter, Johannes Kofler, Rupert Ursin, Thomas Jennewein, Časlav Brukner, and Anton Zeilinger. Nature Physics (2012) DOI: 10.1038/NPHYS2294

The Daily Galaxy via University of Vienna

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Comments

[Noochy]

wow, intense. i still don't really get it.

[radii]

entanglement and nonlocality - blah blah ... what a waste of time, literally ... particles exist in several states simultaneously since they are oscillating - duh ... so these conclusions about influencing the future and all that is bunk - we're talking particles and constituent parts of particles .. the observer affects the outcome

[j]

in lay-mans terms, a sufficiently advanced device using this technology could determine what you see, after you have seen it.

[dr burke]

Entanglement is the 'root' cause for gravity. Electron entanglement is directly
proportional to the square of electron mass; hence, gravity. The
greater the entanglement of electron interaction, the greater gravity is

Electron entanglement X D = Gravity squared. .

[the past means nothing then]

Are you saying that what has happened might not have happened after all? If we choose to change it latter(and have the technology). And that you can alter your past by actions you take in the future? I'm confused (or am I).

[nudrool]

I'll decide if I already knew that later.

[Gaugain Perpignac]

don`t worry, there`s no implications in real life, what happens at quantum level stays in quantum level.

[Dave]

I can't figure out if Noochy is an awesomely intelligent troll having a go, or a complete moron. I'm going to go with "he's a bored physics student."

[Bob Greenwade]

This, to my mind, is a step toward using quantum entanglement for communication, which would eliminate the necessary delay when communicating over interplanetary -- and, eventually, interstellar -- distances. I'm not quite sure how it would work (if I did, I'd be in the running for a Nobel in Physics, and I'd rather go for the Literature one), but I do think we're working toward that whether we know it or not.

[somebody]

@ Bob Greenwade
cannot be used for communication, information cannot be transferred faster then speed of light. When you measure a property of entangled particle (spin etc) what you get is one of the random states.
you cannot influence what particular state should be ( no information transfer).
think about as two dices- they both spinning and then you decide to stop one( measure a property). it could be any side of dice (the other dice will show the same entangled side ) but you cannot make dice to be stopped on particular side.

[smartypants]

somebody
I believe Bob was speaking about how some particles "pair up" and seem to communicate instantly no matter how far apart they are (quantum entanglement). Here is a page on it if you are interested.

http://io9.com/5277700/scientists-measure-communication-between-quantum-entangled-atoms

[somebody]

@smartypants
well as I mentioned, they are entangled -it just you cannot be used to transfer information. communication is "instantaneous" but random

[smartypants]

I just hope they are not so entangled they dont trip over each other all the time.

And yes, with our current technology we cannot use them to move information. But we are smart and sooner or later we will.

[Jack Butler]

Since supposedly just before the big bang all matter and energy were contained in a single undifferentiated unthinkably dense particle, how come everything in the universe is not entangled?

Or--(ominous booming music over) IS IT?

[Gabriel A. C.]

How about this. Receiver in the past receives either separate photon or entangled photon. Let separate photon be equal to bit 1. Let entangled photon be bit 0. Transmitter in the future codes the message in ASCII using zeros and ones following that equivalency. There you go. You are sending information from the future to the past.