A Refined Approach to Quantum Superposition

Quantum superposition is a bizarre, not very well understood phenomenon, and quite possibly, spooky action-ish at best.

Quantum superposition is a fundamental principle of quantum mechanics. It states that, much like waves in classical physics, any two (or more) quantum states can be added together ("superposed") and the result will be another valid quantum state; and conversely, that every quantum state can be represented as a sum of two or more other distinct states. Mathematically, it refers to a property of solutions to the Schrödinger equation; since the Schrödinger equation is linear, any linear combination of solutions will also be a solution.

As many of you are familiar, the double slit experiment introduced us to the weirdness of quantum superposition. The video provided below is a basic demonstration of the double slit experiment, should you be interested in learning about it or need a refresher.





The double slit experiment showed us this odd, dualistic nature of particles, but did not give us much to go on, as the simple action of observing seemed to "collapse" the quantum superposition.

Scientists were and remain confounded, but some are eager to devise an experiment that should give more insight into quantum superpoisition and the possible locations of photons during these moments.

For decades researchers have stalled at this apparent impasse. They cannot say exactly what a superposition is without looking at it; but if they try to look at it, it disappears. One potential solution—developed by Elitzur’s former mentor, Israeli physicist Yakir Aharonov, now at Chapman University, and his collaborators—suggests a way to deduce something about quantum particles before measuring them. Aharonov’s approach is called the two-state-vector formalism (TSVF) of quantum mechanics, and postulates quantum events are in some sense determined by quantum states not just in the past—but also in the future. That is, the TSVF assumes quantum mechanics works the same way both forward and backward in time. From this perspective, causes can seem to propagate backward in time, occurring after their effects.

Now Elitzur and Cohen have teamed up with Okamoto and Takeuchi to concoct an even more mind-boggling experiment. They believe it will enable researchers to say with certainty something about the location of a particle in a superposition at a series of different points in time—before any actual measurement has been made.

Below is a diagram of the planned experiment:

The experiment is designed so the probe photon can only show interference if it interacted with the shutter photon in a particular sequence of places and times: Namely, if the shutter photon was in both boxes A and C at some time (t1), then at a later time (t2) only in C, and at a still later time (t3) in both B and C. So interference in the probe photon would be a definitive sign the shutter photon made this bizarre, logic-defying sequence of disjointed appearances among the boxes at different times—an idea Elitzur, Cohen and Aharonov proposed as a possibility last year for a single particle spread across three boxes. “I like the way this paper frames questions about what is happening in terms of entire histories rather than instantaneous states,” says physicist Ken Wharton of San Jose State University, who is not involved in the new project. “Talking about ‘states’ is an old pervasive bias whereas full histories are generally far more rich and interesting.”

So although the traditional “two places at once” view of superposition might seem odd enough, “it’s possible a superposition is a collection of states that are even crazier,” Elitzur says. “Quantum mechanics just tells you about their average.” Post-selection then allows one to isolate and inspect just some of those states at greater resolution, he suggests. Such an interpretation of quantum behavior would be, he says, “revolutionary”—because it would entail a hitherto unguessed menagerie of real (but very odd) states underlying counterintuitive quantum phenomena.

This experiment could be groundbreaking, but could very well lead to further confounding.

Regardless, although these scientists won't be directly observing the quantum superposition, my bet is they'll be intently staring at computer monitors, waiting for their data files to pop up, a bit like this:







Source material:

www.scientificamerican.com...

en.m.wikipedia.org...

www.sciencemag.org...

I always liked Feynman's explanation



He mentions the uncertainty principle and how it relates to the experiment and how the measuring apparatus themselves can collapse the pattern.
I believe he always defined observer as 'the thing that causes the waveform to collapse.'

a reply to: CreationBro

WHOA....I do not know too terribly much about this subject but man this is fascinating.
Thanks for putting a giant of plate of stuff on my table. WOW

a reply to: CreationBro

I've been absorbing myself in this subject the last few months trying to better understand.

It sounds like this experiment is just another way to 'observe,' and thus will collapse the wave function...a fancier version of the double slit that will produce similar results?

I admit I'm too stoopid to really understand it all though.

a reply to: CreationBro

I propose the following experiment:

Essentially, it is a crossover experiment incorporating Shroedingers cat and Pavlov's dogs.

The differences are that a small spherical bell is placed in the box along with the cat and the poison gas and the isotopic release mechansim.

Eventually, the cat will discover the bell and begin playing with it, as cats do.

The dogs, trained to expect food when a bell is rung, will become increasingly anxious and hungry and will investigate the source of the bell noise, opening the box and discovering a cat.

Determinacy restored!

originally posted by: NarcolepticBuddha
a reply to: CreationBro

I've been absorbing myself in this subject the last few months trying to better understand.
It sounds like this experiment is just another way to 'observe,' and thus will collapse the wave function...a fancier version of the double slit that will produce similar results?

I admit I'm too stoopid to really understand it all though.

Youre definitely not stupid buddha. That is a totally plausible idea, that any form of observation will not "trick" the system.

originally posted by: chr0naut
a reply to: CreationBro

I propose the following experiment:

Essentially, it is a crossover experiment incorporating Shroedingers cat and Pavlov's dogs.

The differences are that a small spherical bell is placed in the box along with the cat and the poison gas and the isotopic release mechansim.

Eventually, the cat will discover the bell and begin playing with it, as cats do.

The dogs, trained to expect food when a bell is rung, will become increasingly anxious and hungry and will investigate the source of the bell noise, opening the box and discovering a cat.

Determinacy restored!

Chr0naut's CatDog Experiment (wherein a cat and dog exist as one being in superposition, perhaps?)

We'll get to the finer details of it later, but I likey!

Cat and dog (perhaps a genetically abominable amalgamation "CatDog")?
Check!

Isotopic release mechanism?
Check!

Bells?
Check!

Hunger?
Check!

Anxiety???
Check!

POISON #IN GAS?!?

YOU BET YOUR ASS CHECK!


How could this not win you the Nobel?

a reply to: chr0naut

Thank you!!

I really needed a laugh! Been a bit too serious lately (and a little judgemental), so anything to lighten my mood is welcome!

Cat vs dog is the heart of QM. Bell’s theorem being upheld makes the explanation more difficult.

Damn inverse mathematical relationships!

a reply to: CreationBro

I want to thank the OP profusely!

I earlier today came on this subject on a blog and was fascinated by this same problem that the blog highlighted
www.salon.com...

Didn’t completely understand it. Your little video explained it clearly. It's a fascinating problem.

a reply to: Willtell

Thanks man.

I know, this stuff is fascinating (and mind boggling).

a reply to: CreationBro

S+F for the OP from me as well.

I will link the Bell’s theorem link in when off mobile. Spooky action at a distance is real. And that is confusing in and of itself to spark thread wars for years to come.

a reply to: CreationBro

It certainly is.


The thing is not more than a few hours ago I was on Salon, and read the link I gave and was fascinated and then went on ATS and saw your op and immediately went to it.

The part about the phenomenon changes when they observe it has amazing implications.

Thanks again for the well-timed OP

The great thing about ATS is you learn on it often and that in itself is worth the time

a reply to: CreationBro

So although the traditional “two places at once” view of superposition might seem odd enough, “it’s possible a superposition is a collection of states that are even crazier,” Elitzur says. “Quantum mechanics just tells you about their average.”

This just sounds exactly like the Copenhagen interpretation to me and it's exactly the result I would have predicted. By attempting to pin down the location of the photon they collapse the wave function and destroy the superposition, forcing the photon to take on only one state out of a collection of possible states.

originally posted by: CreationBro

originally posted by: chr0naut
a reply to: CreationBroI propose the following experiment:

Essentially, it is a crossover experiment incorporating Shroedingers cat and Pavlov's dogs.

The differences are that a small spherical bell is placed in the box along with the cat and the poison gas and the isotopic release mechansim.

Eventually, the cat will discover the bell and begin playing with it, as cats do.

The dogs, trained to expect food when a bell is rung, will become increasingly anxious and hungry and will investigate the source of the bell noise, opening the box and discovering a cat.

Determinacy restored!

Chr0naut's CatDog Experiment (wherein a cat and dog exist as one being in superposition, perhaps?)

We'll get to the finer details of it later, but I likey!

Cat and dog (perhaps a genetically abominable amalgamation "CatDog")?
Check!

Isotopic release mechanism?
Check!

Bells?
Check!

Hunger?
Check!

Anxiety???
Check!

POISON #IN GAS?!?

YOU BET YOUR ASS CHECK!

How could this not win you the Nobel?

Sadly, the selection panel have deemed my experiment "out of scope" for a prize (apparently because the experiment mandates the use of a bell).

I will, however, be presenting it as the keynote for the 17th Mad Science awards in July.

Although, they are a tough crowd to predict.

For instance, my old paper "Boron: two insults for the price of one" recieved hardly a notice, but last year's; "Repurposing Magnetrons from Old Microwave Ovens as a Death Ray" recieved the highest accolades (it also recieved attention from Homeland Security but my benefactor paid them off made a donation that pleased them. What surprised me most was their willingness to accept payment in Roubles).

I also have a backup paper to present in case the "Cat/Dog Determinacy experiment" falls flat, "Smoke detectors: steps towards the Dirty Bomb on a Budget" (a sure crowd pleaser).