Schrodinger's Cat Closer To Reality?

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Schrodinger's Cat Closer To Reality?

Posted by simoniker on Wednesday October 1, 2003 @07:28PM from the mew-mew-mewmew dept.

Shipud writes "A group from the University of Oxford is proposing a scheme to achieve quantum superposition in a large object, according to Nature - not as large as Schrodinger's cat, but about ten-thousandth of a square millimiter, some 10^14 atoms. Quantum superposition is the phenomenon in which a photon passing through a beam splitter to takes two paths at once, inconceivable in the macroscopic world. William Marshall and co-workers suggest to mount a tiny mirror on a springy arm, so that the power of a single photon will be enough to oscillate it. When that photon is superposed, it transfers its superposition to the mirror, which will be quantum superposed: at two places at once. Wave particle duality has already been shown in Buckminster fullerenes, a 60 atom compound. Are we getting closer to quantum computers?"

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Yeah... by Kiriwas · 2003-10-01 19:34 · Score: 3, Interesting

Achieving superposition is great, but how long is it maintainable? To get truly useful quantum computers, we need states that can be maintained that way, for longer periods of time (or so at least some proposed versions say). fp?
1. Re:Yeah... by drkich · 2003-10-01 19:48 · Score: 3, Insightful
  
  The researchers propose to calm this stormy background by cooling the apparatus to less than two thousandths of a degree above absolute zero. The mirrors would also be in a very high vacuum so as not to be disturbed by colliding gas molecules.
  It does not sound like it will be in a case near you any time soon.
  Plus it will be in a high vacuum, not a perfect vacuum. So even though the probability of the mirror hitting any gas molecules is low, how reliable are their results?
  
  --
  Mid-Eastern Pennsylvania Gaming Convention
2. Re:Yeah... by Nickybob · 2003-10-01 19:53 · Score: 2, Insightful
  
  I don't mean to be a spoil sport, but even if they accomplish superposition, we still have Heisenberg to consider, right?
3. Re:Yeah... by drkich · 2003-10-01 23:58 · Score: 1
  
  Don't you know anything? That is where we pull out the Heisenberg Compensator out.
  
  --
  Mid-Eastern Pennsylvania Gaming Convention
4. Re:Yeah... by Mattcelt · 2003-10-02 00:09 · Score: 1
  
  a photon passing through a beam splitter to takes two paths at once, inconceivable in the macroscopic world
  
  Forgive me if I'm being dense, but don't all particles and waves travel all possible paths all the time? It was my understanding that when a photon travels from point A to point B it does so using every possible path until the waveform coalesces. This works for electrons as well, due to wave-particle duality. I think I disagree with the poster that this *does* actually happen in the macroscopic world all the time, but the waveforms coalesce so fast we never see anything "out of the ordinary".
  
  Does that make sense?
5. Re:Yeah... by russellh · 2003-10-02 01:28 · Score: 1
  
  Achieving superposition is great, but how long is it maintainable?
  I've heard yoga and meditation can help.
  
  --
  must... stay... awake...
6. Re:Yeah... by isaac · 2003-10-02 01:43 · Score: 4, Funny
  
  I don't mean to be a spoil sport, but even if they accomplish superposition, we still have Heisenberg to consider, right?
  
  I'm not sure. Maybe we do, and maybe we don't. We'll probably never know for certain.
  
  --
  I am not a lawyer, and this is not legal advice. For Entertainment Purposes Only.
7. Re:Yeah... by AKAImBatman · 2003-10-02 02:29 · Score: 1
  
  but don't all particles and waves travel all possible paths all the time? It was my understanding that when a photon travels from point A to point B it does so using every possible path until the waveform coalesces.
  
  Ok, my turn to be dense. Aren't you referring to the fourth dimension? A given object/particle will fill every point between its start and its destination. The only reason these points don't collide is that they are plotted along the forth dimension instead of the third. The third dimension is merely a point in the fourth dimension that we perceive. It's not too surprising that we can't interpret the fourth dimension tho. Our brains/bodies rely on the "travel" of energies and matter through the fourth dimension. Thus through a set of sensors (light, vibration, friction, chemical analysis, etc.) we are able to deduce a point in the fourth dimension that existed several "moments" before we finished processing the data.
  
  --
  Javascript + Nintendo DSi = DSiCade
8. Re:Yeah... by QEDog · 2003-10-02 03:48 · Score: 1
  
  It was my understanding that when a photon travels from point A to point B it does so using every possible path until the waveform coalesces.
  The Path Integral interpretation says that the photon travels every possible path if you do not meausure it while is traveling. The double-slit experiment, in this case, can be understood as limiting the possible paths to only 2 at a particular line (you assume it can only go through one slit or the other).
  
  --
  "There is no teacher but the enemy."-Mazer Rackham
9. Re:Yeah... by fifedrum · 2003-10-02 04:37 · Score: 1
  
  oh for a fist full of mod points, +5 funny that one
10. Re:Yeah... by Jerf · 2003-10-02 05:14 · Score: 2, Informative
  
  So even though the probability of the mirror hitting any gas molecules is low, how reliable are their results?
  
  All experiments have a reliability less then 100%. Techniques to handle that have been around for a long time.
  
  Rest assured the experiment will be performed many, many more times then just "once". (It seems to me you have that as part of your mental image.) Supercollider experiments are run into the hundreds or thousands of times (not certain, not part of that community, could easily be millions for all I know; corrections welcomed).
Can they... by drkich · 2003-10-01 19:34 · Score: 3, Funny

I would love to be able to stay up really freakin' late and sleep at the same time. Now that would be a break through!

--
Mid-Eastern Pennsylvania Gaming Convention
1. Re:Can they... by orasio · 2003-10-03 08:11 · Score: 1
  
  I can do that while coding college projects. Come to think of it, quantum logic might have something to do with the results, like when I spot awful pieces of code that I would swear I didnt write.
Lets get this out of the way by Anonymous Coward · 2003-10-01 19:52 · Score: 0

In Soviet Russia, photons superpose you!
Well... by nsebban · 2003-10-01 20:01 · Score: 1

Are we getting closer to quantum computers ?

Well, that question can only be answered by a quantom computer :(

--
____
nico
Nico-Live
Interesting! by floydigus · 2003-10-01 20:17 · Score: 4, Funny

Quantum superposition is the phenomenon in which a photon passing through a beam splitter to takes two paths at once, inconceivable in the macroscopic world.

Whereas Slashdot is the phenomenon in which a sentence takes two paths at once.

--
All things in moderation; including moderation
1. Re:Interesting! by richie2000 · 2003-10-02 19:03 · Score: 1
  
  Mod Parent Up!
  
  --
  Money for nothing, pix for free
2. Re:Interesting! by floydigus · 2003-10-02 20:05 · Score: 1
  
  You are so not original.
  
  --
  All things in moderation; including moderation
Open the box and see by Dancin_Santa · 2003-10-01 20:17 · Score: 5, Funny

Are we getting closer to quantum computers?

Maybe.
1. Re:Open the box and see by KDan · 2003-10-01 20:28 · Score: 2, Insightful
  
  Why do people posting about cool physics stuff invariably feel the need to pepper it with buzzwords like "quantum computers" and what not? This article is interesting and cool and fun without the buzz-reference...
  
  Daniel
  
  --
  Carpe Diem
2. Re:Open the box and see by vudufixit · 2003-10-01 22:01 · Score: 1
  
  Are we getting closer to quantum computing? Yes and no.
3. Re:Open the box and see by bruthasj · 2003-10-01 23:38 · Score: 1
  
  Sir,
  
  Your answer as requested:
  
  Imagine a beowulf cluster of these!
  
  Thank you,
  Slashdot Reader
4. Re:Open the box and see by Anonymous Coward · 2003-10-02 03:25 · Score: 0
  
  Can't you guys come up with funnier quantum related jokes? Christ.
5. Re:Open the box and see by QEDog · 2003-10-02 03:51 · Score: 1
  
  "Can't you guys come up with funnier quantum related jokes? Christ."
  The /. uncertainty principle prohibits to talk about QM and joke too much at the same time.
  
  --
  "There is no teacher but the enemy."-Mazer Rackham
The are copying other media. by DrSkwid · 2003-10-01 21:43 · Score: 1

I find it really annoying

"scientists say that if successful this project could end world hunger and all wars forever"

--
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
Are we getting closer to quantum computers? by Anonymous Coward · 2003-10-01 21:54 · Score: 0

Are we getting closer to quantum computers?

Yes..........and no.
1. Re:Are we getting closer to quantum computers? by Anonymous Coward · 2003-10-02 14:06 · Score: 0
  
  The answer of course is:
  
  42!
Closer to reality? by henrygb · 2003-10-01 21:59 · Score: 3, Insightful

Not until they have done the experiment.
This is a hypothetical experiment at this stage. Until they actually try, they will not know if they can actually detect the effect of "the system [cycling] back and forth between a superposition of photon states (in which case one can detect an interference pattern) and a superposition of mirror positions (for which there is no photon interference pattern)." It is possible that it cannot be detected (either since observing whether or not there is an interference pattern may destroy the cycling process or because the cycling is not happening at all), in which case it becomes a philosphical question rather than a scientific one.
No Clue by Anonymous Coward · 2003-10-01 23:34 · Score: 0

Are we getting closer to quantum computers?
Translation: the poster hasn't a fucking clue what this has to do with quantum computers, if anything.
1. Re:No Clue by Anonymous Coward · 2003-10-02 07:06 · Score: 0
  
  You are right. He does
Smoke and mirrors by Froggie · 2003-10-01 23:39 · Score: 1

Great, not only can we have quantum computers that calculate all the possible answers at once, but now that we can superpose mirrors,we can display them *all at the same time*!
Canonical answer by jolshefsky · 2003-10-01 23:44 · Score: 4, Funny

The question:
Are we getting closer to quantum computers?

The answer:
Yes and no.

--
--- Jason Olshefsky
Karma: Poser (mostly affected by adding this line long after everyone else did)
1. Re:Canonical answer by ENOENT · 2003-10-02 07:37 · Score: 1
  
  Classic. Almost as good as the classic definition:
  
  Recursion: see Recursion
  
  --
  That's "Mr. Soulless Automaton" to you, Bub.
2. Re:Canonical answer by Anonymous Coward · 2003-10-02 23:38 · Score: 0
  
  Wanted: Schrodinger's Cat, dead and alive.
Obligatory quote by ManxStef · 2003-10-02 00:21 · Score: 2, Funny

inconceivable in the macroscopic world.
You keep using that word. I do not think it means what you think it means.
1. Re:Obligatory quote by Cyno01 · 2003-10-02 00:58 · Score: 1
  
  Inconceivable!
  
  --
  "Sic Semper Tyrannosaurus Rex."
2. Re:Obligatory quote by anim8 · 2003-10-02 03:50 · Score: 1
  
  You keep using that word. I do not think it means what you think it means.
  +2 Funny. A reference to "Princess Bride". Moderators: go rent the movie.
3. Re:Obligatory quote by hangingonwords · 2003-10-02 15:35 · Score: 0
  
  Hello, my name is Inigo Montoya, you killed my father, prepare to die.
  
  --
  fact: microsoft > linux
heating up counts as a measurement by QEDog · 2003-10-02 00:32 · Score: 3, Interesting

The cantilever (vibrating arm) is connected to something (the outside). Even if you cool it down a lot, to prevent thermal effects from the outside, the vibrations of the cantilever will heat up the system, and this counts as an observation. The paper doesn't mention how to correct this.

--
"There is no teacher but the enemy."-Mazer Rackham
1. Re:heating up counts as a measurement by radtea · 2003-10-02 01:37 · Score: 4, Insightful
  
  This is a good point, but I'm sure the researchers have considered it. The limiting factor will be inelastic flexion of the cantilever, which can be made small in a number of ways, not least of which is keeping the amplitude of vibration small. Given that they're talking about setting the thing vibrating using the momentum transfer from a single photon, this shouldn't be a huge problem!
  
  But it does bring up an important common misunderstanding that the headline of the article repeats: quantum effects have absolutely nothing to do with size and everything to do with complexity. A photon that passes through both slits of a double-slit apparatus demonstrates quantum effects on a scale of a fraction of a millimeter (the separation distance of the slits) and large multi-path interferometers of one kind or another involve photons that take paths that are tens of centimeters or more apart.
  
  Size doesn't matter. What matters is the number of modes available, because interference between modes destroys our ability to observe quantum effects. Systems of many particles (particularly at higher temperatures) have so many modes available that the coherence time is extremely small, although even then we can under the right circumstances observe things like the Mossbauer Effect in which an entire block of material acts as a single quantum-mechanical entity.
  
  --Tom
  
  --
  Blasphemy is a human right. Blasphemophobia kills.
2. Re:heating up counts as a measurement by QEDog · 2003-10-02 03:19 · Score: 1
  
  This is a good point, but I'm sure the researchers have considered it.
  The paper doesn't address this issue, nor the references.
  The limiting factor will be inelastic flexion of the cantilever, which can be made small in a number of ways, not least of which is keeping the amplitude of vibration small.
  Even if you use small amplitudes or an almost ideal cantilever, the cantilever is still part of a bigger system with a thermal source (the outside, infinite degrees of freedom, yaddy yaddy yadda). My questions is not only considering thermal exchange, but also just the fact of leaking the wave fuction of the cantilever to "the outside".
  It is well known that since "the outside" has so many degrees of freedom, they will somehow measure the cantilever, collapsing it to some eigenstate.
  The only idea around this that I can think of is a floating, isolated mirror in a vacuum chamber. And even then you have to watch out for the force you use to "float" the mirror, make sure it doesn't couple with the mirror state Hamiltonian. Other wise, once again, it would make "the outside" and the mirror part of the same system, ruining the isolation.
  The hard part of doing QM effects on cats (big systems) is that it gets harder and harder to close the system to the rest of the universe. A lot of people have suggested that this is what makes everything look so classical in our everyday experience.
  
  --
  "There is no teacher but the enemy."-Mazer Rackham
3. Re:heating up counts as a measurement by Anonymous Coward · 2003-10-02 03:34 · Score: 0
  
  Every once in a while I see a discussion that reminds me why I love Slashdot :)
4. Re:heating up counts as a measurement by R2.0 · 2003-10-02 05:00 · Score: 1
  
  "Size doesn't matter."
  
  Women always say that. They lie.
  
  --
  "As God is my witness, I thought turkeys could fly." A. Carlson
5. Re:heating up counts as a measurement by jafuser · 2003-10-02 06:09 · Score: 1
  
  The limiting factor will be inelastic flexion of the cantilever [...]
  
  Perhaps the limits could be expanded if you used a nanopulsed hyperinversion polarity tachyon field to reharmonize the chronometric particles?
  
  --
  Please consider making an automatic monthly recurring donation to the EFF
6. Re:heating up counts as a measurement by radtea · 2003-10-02 11:39 · Score: 1
  
  Even if you use small amplitudes or an almost ideal cantilever, the cantilever is still part of a bigger system with a thermal source (the outside, infinite degrees of freedom, yaddy yaddy yadda). My questions is not only considering thermal exchange, but also just the fact of leaking the wave fuction of the cantilever to "the outside".
  
  The note in Nature says they're going to keep everything very cold, which addresses this problem. Cooling can be viewed as "pumping away degrees of freedom", at least in a quantum solid where a given mode becomes exponentially unavailable below its excitation energy.
  
  If simply being in contact with something that was connected with the warm, mode-rich outside world via a cooling apparatus was a problem for an experiment like this, then it would also be a problem for superposition experiments with superfluids and superconductors. Given that cooling solves the problem in those cases, it will solve the problem in this case as well.
  
  The hard part of doing QM effects on cats (big systems) is that it gets harder and harder to close the system to the rest of the universe.
  I believe the more important effect is that cats (complex systems) have many modes themselves, which are strongly coupled to each other, so that that any effect that depends on the long-term or long-range coherence of any given mode (i.e. any quantum effect) is obliterated. My own cat, Yogurt, is trying to help me type this, and he agrees with me.
  
  --Tom
  
  --
  Blasphemy is a human right. Blasphemophobia kills.
7. Re:heating up counts as a measurement by 11223 · 2003-10-02 17:04 · Score: 1
  
  Please go back and watch TNG. They had better jargon than Voyager.
"Are we getting closer to quantum computers?" by psyconaut · 2003-10-02 03:20 · Score: 1

Quantum mechanics research doesn't necessarily parle into bringing us closer to quantum computing! There is much heavy-lifting required in many, many areas...not just duality/entanglement and other popular areas.

-psy
1. Re:"Are we getting closer to quantum computers?" by 2marcus · 2003-10-02 03:34 · Score: 1
  
  I still like using NMR and hydrogen spin states in common organic molecules to do quantum computing. The number of Q-bits is equal to the number of different hydrogens on a single molecule, and you can target each hydrogen with a separate magnetic pulse to manipulate that bit.
  
  Making a "macroscopic" object enter a quantum state is really cool, but I don't foresee it being a step directly towards quantum computing. (Though there may be spin-off learning).
  
  Of course, one would imagine that the wavefunction of an object that large would collapse very quickly as it will be hard to prevent interaction with the environment.
No Heisenberg here by QEDog · 2003-10-02 03:45 · Score: 1

Heisenberg's uncertainity principle only applies to Non-Commuting variables (like position and momentum). The interference effect here is not trying to measure one in terms of the other, so it is not an importat effect.

--
"There is no teacher but the enemy."-Mazer Rackham
Seems like we've been here before... by malakai · 2003-10-02 04:05 · Score: 1

Didn't Fenyman have experiments done with two holes in a divider between a photon emmiter and detector? Every attempt to measure which hole a photon went through on it's way to a detector collapsed the system such that the photon took only one path. No Interference.

Sounds to me like nature has code to see if a debugger is attached to her processes, and if so, she ain't going to show you what she really does when you aren't looking.

--
-Malakai
A Dragon Lives in my Garage
1. Re:Seems like we've been here before... by 11223 · 2003-10-02 17:11 · Score: 1
  
  I wonder how many people actually get your sig. Perhaps if you took out the quotes, you'd get a response to it?
  
  Can I see the footprints? :-)
Thank you for the biggest laugh of the day so far by SolemnDragon · 2003-10-02 04:19 · Score: 1

And i mean that for real; i almost fell off my chair. Obvious, but somehow.... hysterical.

--
"I'd say 'Have a good time,' but arson is still illegal.
My Own Experiment by jameskojiro · 2003-10-02 04:29 · Score: 0

Well, I for one tried something simular.

I took a black cat and threw it at a mirror to see if it would take two paths, unfourtunately it broke the mirror (7 years bad luck), bounced off afformentioned broken mirror, knocked over the salt shaker on the kitchen table (more bad luck), crossed my path while running away from (bad luck), I chased it under a ladder as it fled my house (even more bad luck).

Right now i am cowering under my desk with a four leaf clover. And I thought practical physics was safe....

--
Tsukasa: All I really want, is to be left alone...
Hacking the Matrix, err.. I mean reality... by Anonymous Coward · 2003-10-02 12:51 · Score: 0

Sounds to me like nature has code to see if a debugger is attached to her processes, and if so, she ain't going to show you what she really does when you aren't looking.

This is an amusing observation/metaphor. It certainly does make one pause and ask some interesting questions.

Luckily, however, we humans are pretty good hackers/crackers... We seem to be learning how to observe without observing... But perhaps, there is an even deeper counter-measure putting the brakes on these methods of hacking The Matrix, err.. I mean... reality... ;-)

Your observation does beg this question, no? (The existance of observational countermeasures provides evidence of the possibility of deeper countermeasures)

Alright, I know... Conspiracy theories on the nature of the universe are just a little to slashdot, and Occum's Razor does come to the rescue... But it sure is a fun idea to toy with...
On solving Shroedinger's cat. by azav · 2003-10-02 14:43 · Score: 1

It's amazing that people haven't figured this out already.

If the rules state that you can not directly observe the cat, then you indirectly observe the cat.

You observe byproducts or effects of the cat. Observing the things that the cat influences - be it live or dead will tell you the state of the cat.

Sooo, in a stretch, it is possible to get closer to that which Shroedinger and Heisenberg stated were not possible.

--
- Zav - Imagine a Beowulf cluster of insensitive clods...
1. Re:On solving Shroedinger's cat. by howlingfrog · 2003-10-02 17:33 · Score: 1
  
  If the rules state that you can not directly observe the cat, then you indirectly observe the cat.
  
  The distinction between "direct" and "indirect" observation is meaningless in this context. Observation is observation. Whenever ANYTHING requires the cat's waveform to collapse, it will collapse.
  
  --
  The original Howling Frog is a fictional character and has no UID.
2. Re:On solving Shroedinger's cat. by azav · 2003-10-02 19:38 · Score: 1
  
  After a nice little New Scientist search, I see evidence that quantum states can be determined by observation of what they affect without influencing their state. Soooo, I just might be right in the case below.
  
  http://www.newscientist.com/news/news.jsp?id=ns9 99 93384
  
  "Jian-Wei Pan and colleagues from Anton Zeilinger's group at the University of Vienna had already shown that, in theory, teleportation can be confirmed by monitoring the outcome of the interaction that teleports the qubit. If both photons are detected as expected, it is safe to assume that the quantum state has been teleported."
  
  --
  - Zav - Imagine a Beowulf cluster of insensitive clods...
3. Re:On solving Shroedinger's cat. by Anonymous Coward · 2003-10-03 00:32 · Score: 0
  
  Well thank you, mister Spoil-Sport, for bringing the whole thread to a screeching halt.
4. Re:On solving Shroedinger's cat. by bWareiWare.co.uk · 2003-10-03 00:37 · Score: 1
  
  They where saying you could infer that the quantum state had been teleported by observing the results system after the collapse of the quantum strait. This is not the same as being able to indirectly inferring the quantum state of the system without collapsing it (Schrodinger did not expect any difficulties in telling if the cat was alive once the box was opened). If we could not infer anything about quantum straits and could not measure them then I think it would be safe to say the do not exists. Interestingly you seem to have gotten the New Scientist site very close to a superposition (It is a page telling you that this page is unavailable.)