Wave-particle duality at Macro scale?

[bohm2]

There are some new results from the walking droplets that demonstrate how wave-like statistics arise from an underlying pilot-wave dynamics through deterministic chaos.



What do you think?

The video is summarizing most of the stuff linked above. But what is the microscopic equivalent to the vibrating bath seen in droplet experiments? I've come across papers suggesting some form of "intrinsic periodicity" as per de Brogle's idea suggesting that inside the particle there was a periodic process that was equivalent to a clock. Donatello Dolce has published a few papers on this topic, but I haven't seen it much discussed elsewhere:

We interpret the relativistic quantum behavior of elementary particles in terms of elementary cycles. This represents a generalization of the de Broglie hypothesis of intrinsically “periodic phenomenon”, also known as “de Broglie internal clock”. Similarly to a “particle in a box” or to a “vibrating string”, the constraint of intrinsic periodicity represents a semi-classical quantization condition, with remarkable formal correspondence to ordinary relativistic quantum mechanics. In this formalism the retarded local variations of four-momentum characterizing relativistic interactions can be equivalently expressed in terms of retarded local modulations of de Broglie space-time periodicity, revealing a geometrodynamical nature of gauge interaction.

On the intrinsically cyclic nature of space-time in elementary particles
http://arxiv.org/pdf/1206.1140.pdf

 

[bohm2]

This is another paper by the Gerhard Grossing et al. group that uses some of the insights gained from the bouncing/walking droplets in the experiments of Couder's group to model certain QM phenomena:

In a new approach to explain double-slit interference "from the single particle perspective" via "systemic nonlocality", we answer the question of how a particle going through one slit can "know" about the state of the other slit. We show that this comes about by changed constraints on assumed classical sub-quantum currents, which we have recently employed to derive probability distributions and Bohm-type trajectories in standard double-slit interference on the basis of a modern, 21st century classical physics. Despite claims in the literature that this scenario is to be described by a dynamical nonlocality that could best be understood in the framework of the Heisenberg picture, we show that an explanation can be cast within the framework of the intuitively appealing Schrodinger picture as well. We refer neither to potentials nor to a "quantum force" or some other dynamics, but show that a "systemic nonlocality" may be obtained as a phenomenon that emerges from an assumed sub-quantum kinematics, which is manipulated only by changing its constraints as determined by the changes of the apparatus. Consequences are discussed with respect to the prohibition of superluminal signaling by standard relativity theory...

As we employ no "quantum force", therefore, we consider "systemic nonlocality" as a phenomenon that emerges from a sub-quantum kinematics, which is manipulated only by changing its constraints as determined by the changes of the apparatus. In fact, with our approach we have in a series of papers obtained essential elements of quantum theory. They derive from the assumption that a particle of energy E = ħω is actually an oscillator of angular frequency ω phase-locked with the zero-point oscillations of the surrounding environment, the latter of which containing both regular and fluctuating components and being constrained by the boundary conditions of the experimental setup via the buildup and maintenance of standing waves. The particle in this approach is an off-equilibrium steady-state maintained by the throughput of zero-point energy from its vacuum surroundings. This is in close analogy to the bouncing/walking droplets in the experiments of Couder's group, which in many respects can serve as a classical prototype guiding our intuition.

"Systemic Nonlocality" from Changing Constraints on Sub-Quantum Kinematics
http://lanl.arxiv.org/pdf/1303.2867.pdf

 

[bohm2]

Some 2013 papers that add to this interesting work in this subject:

We demonstrate that a coherent wavelike statistical behavior emerges from the complex underlying dynamics and that the probability distribution is prescribed by the Faraday wave mode of the corral. The statistical behavior of the walking droplets is demonstrated to be analogous to that of electrons in quantum corrals.

Wavelike statistics from pilot-wave dynamics in a circular corral
http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/Harris-Corrals-2013.pdf

Interaction of walking drops and the surface waves reflected from the boundaries or from other drops leads to a variety of interesting phenomena reminiscent of quantum mechanics (Bush 2010). Examples include tunnelling across a subsurface barrier (Eddi et al. 2009b), single-particle diffraction in both single- and double-slit geometries (Couder & Fort 2006), quantized orbits analogous to Landau levels in quantum mechanics (Fort et al. 2010) and orbital level splitting (Eddi et al. 2012). Harris et al. (2013) considered a drop walking in confined geometries, and demonstrated that the resulting probability distribution function is simply related to the most unstable Faraday wave mode of the cavity. Rationalizing these remarkable macroscopic quantum-like phenomena provided the motivation for this study.

Droplets bouncing on a vibrating bath
http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/MB1-2013.pdf

Our results form the basis of the first rational hydrodynamic pilot-wave theory.

Droplets walking on a vibrating bath: Towards a hydrodynamic pilot-wave theory
http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/MB2-2013.pdf

Finally, we have highlighted a mixed state, in which the walking drop shifts between two distinct modes, a state that may serve as an analog of a superposed state in quantum mechanics.

Exotic states of bouncing and walking droplets
http://windw.dk/2013Bouncing.pdf

 

[Hernik]

Another paper on the droplets' quantum like behavour. I'm am not able to judge the paper professionally as I'm not a physicist, but it seems to me it's claiming that the behavour of the droplets are not only quantum like but equivalent to quantum mechanics when the differences of the systems are taken into consideration and if experiments reveal certain diffraction patterns. But I'm certainly not sure I'm right about that assumption?

Droplets moving on a fluid surface: interference pattern from two slits
http://arxiv.org/pdf/1307.6920v1.pdf

 

[Hernik]

..Also the paper mentions that droplets and ANTIdroplets can form from waves meeting each other. Something which seems to take place in experiments with oil as well as water. I'd never heard about that.

 

[eloheim]

So my brain had an idea while reading the latter part of this thread... (And forgive me if this has already been discussed/addressed via reference here.) Could there be interesting things to do with this setup (the walker-table) by augmenting the (classical) 'quantum simulations' with_actual_quantum components/extensions/etc.? Unfortunately I don't have any suggestions off the top of my head but it seems there might be interesting qutantum-classical hybrid interactions/experimental scenarios to be explored? ..Are there constraints working against such endeavors due to the 'table-walker' setup?

Also as a quick more general aside: It's obvious that the 'walker' experiments that are the subject of this thread produce a quite amazing variety of quantum-like effects, especially upon first blush for someone not ever having been exposed to such an experimental setup before, or ever even considered the_possibility_ of such a thing! Acknowledging that--I'm wondering if someone can tell me what 'quantumy' effects it CAN'T reproduce?? ..Also (last q): Are there any lorentz-invariance-related issues hanging around in all this?


Thanks again to those taking time to aggregate sources and reference materials and compose or participate in threads such as this one.(!)

 

[bohm2]

Acknowledging that--I'm wondering if someone can tell me what 'quantumy' effects it CAN'T reproduce??

As acknowledged by the some of these authors themselves in this slide presentation, those experiments are still far from QM for the following reasons:

- Macroscopic scale : no relation with Planck constant.
- The system is two-dimensional.
- The system is dissipative and sustained by external forcing.
- This forcing imposes a fixed frequency: the “energy” is fixed
- The waves live on a material medium: there is an “ether

A macroscopic-scale wave-particle duality
http://www.physics.utoronto.ca/~colloq/Talk2011_Couder/Couder.pdf

Another interesting paper recently published by the Grossing group on their model and Born's rule, they also touch on your latter point regarding lorentz-invariance-related issues, etc. :

It has been shown in a series of papers that phenomena of standard quantum mechanics like Gaussian dispersion of wave packets, superposition, double slit interference, Planck's energy relation, or the Schrodinger equation can be assessed as the emergent property of an underlying sub-structure of the vacuum combined with diffusion processes reflecting also the stochastic parts of the zero-point field, i.e. the zero point fluctuations. Thus we obtain the quantum mechanical results as an averaged behavior of sub-quantum processes. The inclusion of relativistic physics has not been considered yet, but should be possible in principle.

Born's Rule as Signature of a Super-Classical Current Algebra
http://arxiv.org/pdf/1308.5924.pdf

 

[audioloop]

“All our experiences tell us we shouldn't have two dramatically different conceptions of reality — there must be one huge overarching theory,” says Abhay Ashtekar, a physicist at Pennsylvania State University in University Park.

 

[bohm2]

“All our experiences tell us we shouldn't have two dramatically different conceptions of reality — there must be one huge overarching theory,” says Abhay Ashtekar, a physicist at Pennsylvania State University in University Park.

Yes, it seems that unification has been the norm in the sciences but I think that one must also recognize that this is still at most a hope that might not be realized, either because nature really is not unified/monistic, or because human cognitive capacities are not capable of discovering that unity. Either alternative is a possibility, I think.

 

[audioloop]

.

I think that one must also recognize that this is still at most a hope that might not be realized

dont despair, is the zeigeist of this epoch.

because human cognitive capacities are not capable of discovering that unity.

are you agnostic ?.

 

[Hernik]

.dont despair, is the zeigeist of this epoch..

There is hope I think. It is not quantum mechanics. But something which is not purely a wave goes through two holes at one time in a classical system. That takes some of the mystery out of quantum mechanics for me. QM might not be unexplainable after all.

And to me it is exiting to follow the attempts to see how far this droplett-analogy to QM can be stretched. How much of the weirdness from QM it might show parallels to in this limited 2-dimensional system. Entanglement of course is the big one.

- Henrik

 

[audioloop]

There is hope I think. It is not quantum mechanics. But something which is not purely a wave goes through two holes at one time in a classical system. That takes some of the mystery out of quantum mechanics for me. QM might not be unexplainable after all.

And to me it is exiting to follow the attempts to see how far this droplett-analogy to QM can be stretched. How much of the weirdness from QM it might show parallels to in this limited 2-dimensional system. Entanglement of course is the big one.

- Henrik

there are similar results from epistemic models.


.

 

[bohm2]

there are similar results from epistemic models.

But it seems to me, that given some arguably reasonable assumptions, ψ-epistemic models can be ruled out as per PBR theorem? So, if one accepts realism, we are stuck with trying to conceptualize entanglement/non-locality in ontic terms which leads to difficulties as noted by van Fraassen:

To speak of instantaneous travel from X to Y is a mixed or incoherent metaphor, for the entity in question is implied to be simultaneously at X and at Y – in which case there is no need for travel, for it is at its destination already...one should say instead that the entity has two (or more) coexisting parts, that it is spatially extended.

The reality of relations: the case from quantum physics
http://philsci-archive.pitt.edu/9959/1/Relations290813.pdf

It is interesting that quite a few authors are suggesting that our familiar space-time is something that might 'emerge' from some more fundamental stuff that is non-spatio-temporal. On the other hand, if one accepts some form of ontic dualism as some Bohmians (e.g. Bohm, Valentini) do, other problems arise:

However, one can with good reason object that simply adding a quantum force when passing from classical to quantum mechanics is an ad hoc move: that force cannot be traced back to properties of the particles, as the gravitational force can be traced back to mass and the electromagnetic force to charge. Moreover, that force cannot be treated in terms of a field defined on physical space, for it does not permit to assign values to points of space-time. If the wave-function, which is supposed to stand for the quantum force on this view, represents a field, it can only be a field on configuration space, that is, the very high dimensional mathematical space each point of which corresponds to a possible configuration of the particles in physical space. However, it is entirely mysterious how a field on configuration space could influence the motion of particles in physical space.

The reality of relations: the case from quantum physics
http://philsci-archive.pitt.edu/9959/1/Relations290813.pdf

 

[Hernik]

there are similar results from epistemic models..

Yes. I should have been more precise: QM might not be unexplainable in classical terms after all. Lots of explanations already.

 

[bohm2]

are you agnostic ?

No, I just think that like all other organisms we have cognitive limitations. There might be stuff we may never be able to fully understand/conceptualize.

 

[audioloop]

But it seems to me, that given some arguably reasonable assumptions, ψ-epistemic models can be ruled out as per PBR theorem?

imo pbr is not definitive and there are epistemic-ontic models unlike epistemic-epistemic models and ontic models..

 

[jarekd]

Indeed the Couder's experiments are amazing - giving a hope to get below the QM.
I've participated in "Emergent Quantum Mechanics" conference in Vienna two years ago - he gave the opening talk and most of speakers expressed excitation about these experiments. If someone is interested, there is second edition (free admission) in a few weeks and Coder will be there: http://srv14116.omansrv14.omanbros.com/

If we agree that this is the proper view on wave-corpuscle duality, so the next step should be finding a concrete constructions for the real particles: with some localized properties (like charge), conjugated with delocalized wave around, for example caused by an internal periodic dynamics (de Broglie's clock/zitterbewegung).
Localized constructs of the field are generally called soltions, to get e.g. charge conservation we can use topological solitons, and they often have some internal periodic dynamics, like so called breathers ...

How do you see consequences of this view on wave-corpuscle duality?

 

[jarekd]

There are available 3 new papers about these classical objects with wave-particle duality:
One is, like seen in this video, about that their trajectories average to kind of quantum orbitals: http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/Harris-Corrals-2013.pdf
and there are two general papers about their behavior: http://math.mit.edu/~bush/wordpress/wp-content/uploads/2013/07/MB1-2013.pdf , http://windw.dk/2013Bouncing.pdf

If someone is interested in taking this view on wave-corpuscle duality into real particles, there are a few issues:
- the most important should be finding concrete models for particles in this picture: see them as some localized constructs of the field (so called solitons), conjugated with waves they create due to some their internal periodic process (like breathers: http://en.wikipedia.org/wiki/Breather ) - discussion: https://www.physicsforums.com/showthread.php?t=710042
- like in the first paper above, long time thermodynamical behavior of such localized objects should agree with quantum predictions, like leading to the quantum ground state probability distribution. Standard random walks usually disagree with that, but it turns out that if we choose it right (accordingly to the maximal uncertainty principle), there is no longer disagreement of such approaches based on Maximal Entropy Random Walk - discussion: https://www.physicsforums.com/showthread.php?t=710790
- another issue is understanding approximately classical short time behavior of e.g. such electrons - we know that Bohr model does not give a good agreement with quantum predictions. But it neglects that electrons have strong magnetic dipole moment - are tiny magnets. Adding these corrections: classical spin-orbit interaction, we get free-fall atomic model with better agreement - discussion: https://www.physicsforums.com/showthread.php?t=710464

What other issues about seeing particles in this view on wave-corpuscle duality should we have in mind?

 

[Mectaresh]

This is a real cool video show this quantum-like macroscopic behaviour through the double-slit

Yves Couder . Explains Wave/Particle Duality via Silicon Droplets [Through the Wormhole]

https://www.youtube.com/watch?v=W9yWv5dqSKk

Nice video,
I couldn't help but notice that the droplet's waves propagate ahead of it which doesn't seem to be the case at the quantum level.

 

[jarekd]

Mectaresch, see also this video:

Why you think that waves (of quantum phase) does not propagate ahead of particle in QM?
In stationary Schrödinger solution phase changes periodically: exp(-iEt) ... in de Broglie's interpretation particle has some internal periodic motion - is a tiny oscillator, creating waves of quantum phase around - "piloting" the corpuscle (amplitude) e.g. while interference.
You just make Madelung transformation: take psi=R exp(iS) and write Schroedinger equations for this action (S) and density rho=R^2. For density you get standard continuity equation, while for S you get Hamilton-Jacobi equation - exactly like for classical mechanics, but modified by h^2 correction because of interaction with these "pilot" waves of quantum phase: http://en.wikipedia.org/wiki/De_Broglie–Bohm_theory#Derivations

 

[Suwailem]

Another paper on this topic that came out:

Wave-particle duality in classical mechanics
http://lanl.arxiv.org/pdf/1201.4509.pdf

bohm2: Does the "lack of information about all degrees of freedom of a soft body" explain away the Uncertainty Principle as well?

 

[bohm2]

bohm2: Does the "lack of information about all degrees of freedom of a soft body" explain away the Uncertainty Principle as well?

I'm not sure about the details of Davydov's model (in the link) but these models can derive Heisenberg's uncertainty relations. See "Derivation of the Heisenberg Uncertainty relations" in this paper by Grossling:

Sub-Quantum Thermodynamics as a Basis of Emergent Quantum Mechanics
http://www.mdpi.com/1099-4300/12/9/1975

 

[bohm2]

I thought this work on supercorrelations and Bell's theorem is interesting since it seems to be compatible with some of Couder's and Grossing's models:

In systems described by Ising-like Hamiltonians, such as spin-lattices, the Bell Inequality can be strongly violated. Surprisingly, these systems are both local and non-superdeterministic. They are local, because 1) they include only local, near-neighbor interaction, 2) they satisfy, accordingly, the Clauser-Horne factorability condition, and 3) they can violate the Bell Inequality also in dynamic Bell experiments. Starting from this result we construct an elementary hidden-variable model, based on a generalized Ising Hamiltonian, describing the interaction of the Bell-particles with a stochastic ‘background’ medium. We suggest that such a model is a simple version of a variety of recently developed ‘sub-quantum’ theories, by authors as Nelson, Adler, De la Pena, Cetto, Groessing, Khrennikov, all based on a background field. We investigate how the model might be turned into a realistic theory. Finally, it appears that background-based models can be tested and discriminated from quantum mechanics by a straightforward extension of existing experiments.

Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?
http://www.perimeterinstitute.ca/videos/can-sub-quantum-theories-based-background-field-escape-bell-s-no-go-theorem (recent video from Perimeter Institute)

Ref. [34] mentions, as one of its sources of inspiration, recent and spectacular experiments by Couder et al. [36], in which quantum behavior (e.g. double slit interference) is reproduced by macroscopic particles, namely oil droplets. The latter are excited by an external field (the vibration of an oil bed) imparting Brownian motion to the droplets. There seems to be a common denominator in these theories [33-35] and experiments [36], a kind of ‘contextuality’, namely the fact that the precise shape of the (zero-point) field (λ for us) depends on the ‘context’, i.e. the boundary conditions of the whole experimental set-up including the parameters of all, even remote, detectors.

Bell's Theorem: Two Neglected Solutions
http://arxiv.org/ftp/arxiv/papers/1203/1203.6587.pdf

Violation of the Bell-Inequality in Supercorrelated Systems
http://arxiv.org/vc/arxiv/papers/1211/1211.1411v1.pdf

 

[bohm2]

This might be a dumb question but does anybody know what happens to the interference pattern in these quantum-like macroscopic experiments if they place a detector (or some disturbance) behind the slits? Is there any effect on the interference pattern analogous to QM?

 

[bohm2]

This is another piece just written today on the Couder experiments arguing that those experiments are still far away from QM, particularly due to the non-locality/entanglement issue of QM:

One area where the walkers' analogy with quantum mechanics fails, however, is entanglement – the weirdest quantum phenomenon of all that describes how the physical state of two particles can be intricately linked no matter how far apart in the universe they are.

For this to happen, a wave must occupy a very high number of dimensions so particles can affect one another over large distances, faster than the speed of light. However, in a walker system the waves will always occupy just two dimensions, given by the length and width of the oil tank.

"If one thinks of [entanglement] as central to quantum theory, it cannot possibly be reproduced in the [walker] system," Tim Maudlin of New York University told Physics World.

Can an oil bath solve the mysteries of the quantum world?
http://phys.org/news/2013-11-oil-mysteries-quantum-world.html

Having said that, it has been shown by Allahverdyan, Khrennikov and Nieuwenhuizen, that entanglement can be realized in a classical way for a system consisting of two Brownian particles.

We have uncovered the phenomenon of brownian entanglement: a correlation effect between the coordinates and the coarse-grained velocities of two classical brownian particles, which resembles the quantum entanglement. In contrast to the latter, which is presently given a fundamental status, the brownian entanglement —as the very subject of statistical physics— arises out of coarse-graining (incomplete description) reasons. In that respect it is similar to other basic relations of the statistical physics, such as the second law . In the present situation the coarse-graining comes due to the time-scale separation: the evolution of the momenta of the brownian particles is very fast and cannot be resolved on the time-scales available to the experiment.

Brownian Entanglement
http://arxiv.org/pdf/quant-ph/0412132v1.pdf

 

[jarekd]

For this to happen, a wave must occupy a very high number of dimensions so particles can affect one another over large distances, faster than the speed of light. However, in a walker system the waves will always occupy just two dimensions, given by the length and width of the oil tank.

From one side, wave theories in e.g. two dimensions have already infinite number of degrees of freedom - how many more do they need?
From the other, I haven't seen any experiment with "faster than the speed of light" communication(?) ... sure quantum physicists love plane waves - which are spread over the whole Universe, but it doesn't mean they really are - as we know, propagation of information cannot exceed the speed of light.

 

[bohm2]

From one side, wave theories in e.g. two dimensions have already infinite number of degrees of freedom - how many more do they need?
From the other, I haven't seen any experiment with "faster than the speed of light" communication(?) ... sure quantum physicists love plane waves - which are spread over the whole Universe, but it doesn't mean they really are - as we know, propagation of information cannot exceed the speed of light.

I didn't take them as necessarily implying FTL communication. What I don't understand about Maudlin's response is that some researchers like the links above and Grossing have developed models based on Couder stuff for non-locality/entanglement:

A Classical Framework for Nonlocality and Entanglement
http://arxiv.org/pdf/1210.4406.pdf

"Systemic Nonlocality" from Changing Constraints on Sub-Quantum Kinematics
http://arxiv.org/pdf/1303.2867v1.pdf

So, as I see it, I'm not sure Maudlin's point is completely accurate?

 

[kye]

How is bohm pilot wave theory understood in the context of gauge theory? are pilot waves local symmetry gauge or global symmetry gauge entities or are they outside of gauge theory and no connection?

 

[cody1980]

I am certainly a layman, so I ask here in humility and in hopes of improving my understanding. Has anyone tried to perform a similar experiment to Couder's oil droplets but in a three-dimensional setup? I am thinking perhaps that you could have a tank full of fluid and, I dunno, maybe mechanical balls that vibrated at a certain frequency. Would they generate wave fields that would propel them around the tank? Would multiple balls exhibit these same "quantum" effects but in three dimensions? I'm sure the wave patterns could be more complex in three dimensions and might yield more quantum similarities. One advantage of having balls that vibrate instead of causing the medium to vibrate would be that you could have particles of multiple frequencies interacting with one another at the same time. Then again, gravity might throw the experiment off, so ideally it would be done in 0 G, I guess.

 

[bohm2]

Interesting hi-lites from the November 2013 issue of Physics World discussing these experiments:

Indeed, Physics World contacted a number of physicists and philosophers with a background in quantum foundations, and found that most were sceptical that the walker systems could shed light on the mysteries of the quantum world. “The reproduction of two-slit interference is impressive,” says philosopher Peter Lewis from the University of Miami in Florida, US, “but I think the disanalogies between the [walker] system and the pilot-wave theory are just as important as the analogies, and perhaps more so.”...

Most were sceptical – but not all. One exception was theoretical physicist Antony Valentini at Clemson University in South Carolina, US, who points out that walker systems are not the first to present strong analogues of a hard-to-grasp theory: the last decade has seen numerous experimental attempts to produce analogues of gravity, using fluids and light. “People are now wondering if we should look at these [analogue gravity] models and use them for inspiration when we’re looking at how our current theories of gravity might break down at short distances,” he says...

There is already good reason to think that the walkers might exhibit some sort of pseudo nonlocality. Fort and Couder find that the dynamics of walkers is governed largely by the “memory” of past waves, which gradually builds up over the oil bath into a wave field. In this way, the Paris researchers say, one walker can seem to nonlocally affect another walker on the other side of the bath, thanks to a wave – or combination of waves – it emitted previously. This “memory” effect was key to the observed quantization of walker orbits on a rotating oil bath. This year, the researchers demonstrated the memory effect in a more general sense: if a walker is left long enough, its trajectory becomes “entangled” with a wave field in the bath.

Classically quantum
http://physicsworld.com/cws/article/indepth/2013/nov/07/classically-quantum

 

[huelsnitz]

hydraulic quantum analogs

I actually wrote a blog article about this a couple weeks ago:

http://www.thefunisreal.com/2013/10/hydrodynamic-quantum-analogs/

My feeling is that the droplet experiments and quantum systems share similar dynamics. Sort of like a mass on a spring can be explained by the same equations used to describe an RLC circuit. It does not mean the two systems are identical, just that there are dynamical similarities.

So, the message I get from these hydraulic quantum analog experiments is that they can help us understand quantum systems better (particularly after they get more sophisticated). Also, they lend hope to the realist interpretations of QM that seek a conceptual understanding of what is going on, rather than a "shut up and calculate" mentality.

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

This is cool stuff! I love watching the droplet videos again and again.

 

[bohm2]

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

You might find this paper on classical entanglement as an effect of contextuality interesting:

We show that for two classical brownian particles there exists an analog of continuous-variable quantum entanglement: The common probability distribution of the two coordinates and the corresponding coarse-grained velocities cannot be prepared via mixing of any factorized distributions referring to the two particles in separate. This is possible for particles which interacted in the past, but do not interact in the present. Three factors are crucial for the effect: 1) separation of timescales of coordinate and momentum which motivates the definition of coarse-grained velocities; 2) the resulting uncertainty relations between the coordinate of the brownian particle and the change of its coarse-grained velocity; 3) the fact that the coarse-grained velocity, though pertaining to a single brownian particle, is defined on a common context of two particles. The brownian entanglement is a consequence of a coarse-grained description and disappears for a finer resolution of the Brownian motion. We discuss possibilities of its experimental realizations in examples of macroscopic brownian motion.

Brownian Entanglement.
http://arxiv.org/pdf/quant-ph/0412132v1.pdf

 

[billschnieder]

Another "double-slit" experiment using molecules, explained classically, vindicating Einsteins view.
http://prl.aps.org/abstract/PRL/v111/i10/e103201

They use the momentum-transfer-from-discrete-particles description pioneered by William Duane, rather than the wave-particle duality to explain it.

Phys. Rev. Lett. 111, 103201
Momentum Transfer to a Free Floating Double Slit: Realization of a Thought Experiment from the Einstein-Bohr Debates

We simultaneously measured the momentum transferred to a free-floating molecular double slit and the momentum change of the atom scattering from it. Our experimental results are compared to quantum mechanical and semiclassical models. The results reveal that a classical description of the slits, which was used by Einstein in his debate with Bohr, provides a surprisingly good description of the experimental results, even for a microscopic system, if momentum transfer is not ascribed to a specific pathway but shared coherently and simultaneously between both.

 

[TrickyDicky]

Someone mentioned the possibility of going from 2D to 3D fluid experiments.
Do these experiments point towards the possibility of gaining insights about QM from continuum or fluid models(as opposed to many-body models)?

 

[kye]

I actually wrote a blog article about this a couple weeks ago:

http://www.thefunisreal.com/2013/10/hydrodynamic-quantum-analogs/

My feeling is that the droplet experiments and quantum systems share similar dynamics. Sort of like a mass on a spring can be explained by the same equations used to describe an RLC circuit. It does not mean the two systems are identical, just that there are dynamical similarities.

So, the message I get from these hydraulic quantum analog experiments is that they can help us understand quantum systems better (particularly after they get more sophisticated). Also, they lend hope to the realist interpretations of QM that seek a conceptual understanding of what is going on, rather than a "shut up and calculate" mentality.

The MIT group is working on being able to demonstrate entanglement with a droplet experiment.

This is cool stuff! I love watching the droplet videos again and again.

Can the double slit illustration in the droplet videos produced intereference patterns? It's not shown in the Morgan Freeman's documentary. The particle doesn't go straight because there is other waveforms that pass thru the other slit but can they produced the same interference patterns as the quantum double slit experiment?