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Jason Wolfe: on 12/21/17 at 6:09am UTC, wrote I'm pretty sure that Schrodinger equation describes energy states, momentum...

Joe Fisher: on 10/11/17 at 14:25pm UTC, wrote Dear Bashir Yusuf. The real earth existed millions of years before real...

Steve Agnew: on 10/11/17 at 4:30am UTC, wrote Well, it is chemists and not communication engineers who use quantum theory...

Bashir Yusuf: on 10/11/17 at 2:08am UTC, wrote Dear Scientist! Are you aware that recently Physics discoveris have the...

Bashir Yusuf: on 10/11/17 at 1:24am UTC, wrote Dear Steve. The Gravity and Charge, seems to me to be same natural...

Thomas Ray: on 9/10/17 at 23:28pm UTC, wrote Rob, I agree. Unless one deconstructs the equations, however, the case is...

Robert McEachern: on 9/10/17 at 19:26pm UTC, wrote Tom, As I have said many time before, it is the initial conditions and the...

RAHUL DEV: on 9/10/17 at 8:28am UTC, wrote After completing register procedure, Roblox will certainly offer new gamer...


Lorraine Ford: "(continued) 2. Physics has assumed that bottom-up causation IS top-down..." in The Present State of...

Lorraine Ford: "1. Physics can’t tell you why the world ever moves, i.e. physics assumes..." in The Present State of...

Georgina Woodward: "Max? Why?" in Anatomy of spacetime and...

Steve Agnew: "Mueller opens his essay with... "As the argument goes, there are truths..." in Undecidability,...

Dr Narayan Bhadra: "All the Honourable Scientists are cordially requested to feedback that we..." in Undecidability,...

Georgina Woodward: "The mass of the lion entity is not divided between different areas of high..." in Anatomy of spacetime and...

Jim Snowdon: "Since evolving on our rapidly rotating planet, we have used it`s rotational..." in The Quantum Clock-Maker...

Steve Dufourny: "a general universal clock of evolution irreversible correlated for me with..." in The Quantum Clock-Maker...

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Sally Shrapnel, a quantum physicist and medical practitioner, on her experiments into cause-and-effect that could help us understand time’s arrow—and build better healthcare algorithms.

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September 20, 2021

CATEGORY: Blog [back]
TOPIC: Schrödinger’s Cat Meowing Between Many Worlds and Collapse Models [refresh]
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Blogger Catalina Curceanu wrote on Jul. 28, 2017 @ 16:59 GMT
This post is co-written by FQXi members Catalina Curceanu (LNF-INFN, Italy) and Angelo Bassi (Univ. of Trieste and INFN, Italy):

In May, we organised an FQXi-sponsored workshop dedicated to Quantum Foundations at the Laboratori Nazionali di Frascati, LNF-INFN, in Italy, on "'Events' as we see them: experimental test of the collapse models as a solution of the measurement problem." (The event was co-organised with our colleague Kristian Piscicchia, of the Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi Roma, and LNF-INFN Frascati, Italy.)

The aim of the workshop was to discuss the possible limits of the validity of "standard quantum mechanics" and, related to this, collapse models and, more generally, theories which go beyond standard quantum theory and the experiments aiming to test them. In this context, the role which gravity might play was vividly discussed.

From the theoretical point of view, since the almost 100 years old Einstein-Bohr debate, quantum mechanics never stopped raising questions about its interpretation and possible limits. In particular, the transition from the microscopic world, where systems are observed in a superposition of different quantum states, to the macroscopic world, where systems have well defined properties (the so-called "measurement problem"), continues to puzzle (at least part of) the scientific community. For this reason theories/models beyond the standard quantum formulation are explored.

From the experimental point of view quantum theory is certainly the best verified available theory. It is therefore a very compelling challenge to look for possible small violations predicted by alternative theories/models. The aim of ambitious experiments is either to put stronger observational bounds on the new models, i.e. on the models parameters, or, much more exciting, to find violations of standard quantum mechanical predictions. In this framework, a deeper understanding of the possible limits of the validity of the quantum superposition principle is a real experimental challenge.

40 experts and young scientists, theoreticians and experimentalists, and also some philosophers, took part to the workshop and had vivid discussions.

In what follows, we present some of the items discussed during the workshop: Schrödinger’s cat meowing.

How well can we find out whether a wave function has collapsed? asks Roderich Tumulka of Eberhard-Karls University. If the GRW (Ghirardi-Rimini-Weber) theory were true, then how could we measure the number of collapses that have occurred for a given physical system in a given time interval? Roderich provided a mathematical analysis of some simple cases. It turns out that there are limitations to knowledge—that is, that some well-defined quantities cannot be reliably measured empirically.

Matteo Morganti of University of Roma Tre, Roma, discussed the attempt(s) to solve the measurement problem by making quantum mechanics a ‘many-world theory’. Starting from the naïve idea that measurement events literally cause the universe to branch, he moved back to the original ‘relative-state’ proposal made by Everett, and assessed to what extent it really qualifies as a many-world formulation of quantum mechanics. In the process, he considered, albeit briefly, some important issues concerning probabilities, empirical adequacy, decoherence and the philosophical status of the theory (or theories) in question.

Experimental bounds on collapse models from gravitational wave detectors were illustrated by Matteo Carlesso, Univ. of Trieste, Italy. Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder and AURIGA were shown in the framework of the Continuous Spontaneous Localization (CSL) model. These experiments exclude a large portion of the CSL parameter space at high correlation length, or rc, values.

Kristian Piscicchia has shown that for low values of rc, including that originally proposed by GRW, the best constraints come from the measurement of the spontaneous radiation. The interaction with the collapsing stochastic “noise” causes the emission of electromagnetic radiation for charged particles, which is not predicted by standard quantum mechanics, an effect known as spontaneous radiation emission. Comparing the X-ray emitted spectrum measured with ultra-pure Germanium detectors with the expected spontaneous radiation prediction allows to obtain the most stringent limit on the lambda collapse parameter for values of rc below the micron range, and in the near future orders of magnitude better limits are reachable.

An interesting presentation about Cosmic Inflation and Quantum Mechanics was held by Jerome Martin of CNRS, France. According to cosmic inflation, the inhomogeneities in our universe are of quantum mechanical origin. This scenario was recently spectacularly confirmed by the data obtained by the European Space Agency (ESA) Planck satellite. In fact, cosmic inflation represents the unique situation in physics where quantum mechanics and general relativity are needed to establish the predictions of the theory and where, at the same time, we have high accuracy data at our disposal to test the resulting framework. So inflation is not only a phenomenologically very appealing theory but it is also an ideal playground to discuss deep questions in a cosmological context. Jerome reviewed and discussed those quantum-mechanical aspects of inflation. He explained why inflationary quantum perturbations represent a system which is very similar to systems found in quantum optics. He also pointed out the limitations of this approach and investigated whether the large squeezing of the perturbations can allow us to observe a genuine observational signature in the sky of the quantum origin of the cosmological fluctuations.

Hendrik Ulbricht of the University of Southampton, UK, presented recent results on manipulation of levitated optomechanics for tests of fundamental physics, in particular the trapping and cooling experiments of optically levitated nanoparticles. The cooling of all translational motional degrees of freedom of a single trapped silica particle to ~1mK simultaneously at vacuum of 10-5 mbar using a parabolic mirror to form the optical trap were reported, together with the squeezing of a thermal motional state of the trapped particle by rapid switch of the trap frequency. Such experiments are relevant to pave the way towards an experimental test of both the quantum superposition principle and the interplay between gravity and quantum mechanics.

Towards a platform for macroscopic quantum experiments in space, was the subject discussed by Rainer Kaltenbaek of University of Vienna, Vienna Center for Quantum Science and Technology, Faculty of Physics, Austria. Recent developments have rendered space an increasingly attractive platform for quantum-enhanced sensing and for fundamental tests of physics using quantum technology. In particular, there already have been significant efforts towards realizing atom interferometry and atomic clocks in space as well as efforts to harness space as an environment for fundamental tests of physics using quantum optomechanics and high-mass matter-wave interferometry. Rainer presented recent efforts in mission planning, spacecraft design and technology development towards this latter goal in the context of the mission proposal MAQRO and ESA's recent call for New Science Ideas.

Yaakov Fein of the University of Vienna, Austria, discussed the progress at LUMI: the Long Baseline Universal Matter-Wave. At LUMI a Kapitza-Dirac-Talbot-Lau interferometer scheme with a one-meter grating separation is exploited. The aim is to detect interference at a mass scale beyond 100,000 amu, as well as to investigate massive and complex biomolecules, including bounds which can be placed on (certain) spontaneous collapse models.

Mauro Paternostro of CTAMOP, Queen's University Belfast, Ireland, introduced the entanglement between masses as a probe of the quantum nature of gravity. Interactions between two material objects are mediated by fields. If quantum entanglement is created between two such objects due to their interaction, then it follows that the "mediating" field must have been a quantum entity. Mauro first showed that the states of two micron dimension test masses in adjacent matter-wave interferometers could be detectably entangled solely through their mutual gravitational interaction. Then he argued that the purely gravitational mechanism for this entanglement implies that witnessing it is equivalent to certifying the quantum nature of the gravitational field that mediates the entanglement.

The workshop testifies that we are moving from a fruitful present in Quantum Foundation towards an even more exciting future: not only for a better understanding of the quantum universe we live in, but also to set the basis for future quantum technologies on earth and in space.

More information, including the files of the various presentations, can be found on the workshop dedicated web-page.

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Robert H McEachern wrote on Jul. 28, 2017 @ 18:53 GMT
There is nothing peculiar about Schrödinger's cat and Bell Inequality tests, other than the mystery of why the physics community has taken so long to see the obvious.

To start with, consider three types of classical objects, a pair of balls (white and black) a pair of gloves (right and left handed) and a pair of coins. If one of the balls, gloves and coins is given to Alice and the other,...

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attachments: One_Time_Pad_Coins.jpeg

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Steve Agnew wrote on Aug. 5, 2017 @ 19:52 GMT
This conference was very interesting and very topical. Phase decay is a well known part of our quantum universe and it is a natural consequence to use phase decay to limit measurement and entanglement.

This makes gravity different from charge because gravity does not depend on phase while charge does. Continuous spontaneous localization is the latest method science uses to collapse wavefunctions and make sense out of reality. Since coins and other macro objects do not show phase coherence, it is hard to make macro determinate sense from quantum effects.

One thing that is still true is that very smart people continue to argue about the nature of physical reality. Determinists argue for a reality without phase with certain futures without free choice while quantavanglists argue for uncertain futures with free choice.

Now the challenge is to explain how space and time emerge from a simpler reality of matter and action...

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Robert H McEachern replied on Aug. 5, 2017 @ 21:17 GMT
"it is hard to make macro determinate sense from quantum effects." Only because few people have ever looked in the right places. David Bohm had figured much of it out, in his 1951 book "Quantum Theory." For example, he demonstrated that a particle would scatter off any potential with a sharp edge (like that produced by a slit) in a way that would produce a rippled, scattering cross-section (AKA interference pattern). However, being unfamiliar with newly developed Information Theory, he had not been able to figure out why quantum scattering by a field, seems to only happen at discrete points, rather than as a continuous trajectory, like a planet in a classical, gravitational field. But the quantized nature of the information, associated with the scattered particles, provides an answer to that question.

Here are some related thoughts about this

Rob McEachern

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Steve Agnew replied on Aug. 6, 2017 @ 16:52 GMT
You have certainly put a lot of time and effort into this and the DeBroglie-Bohm equation is one way to determine quantum phase by supposing there are hidden variables and pilot waves. There are many very smart people who agree with you but there are many more who disagree.

You do not mention that continuous spontaneous localization (CSL) is yet another way to make wavefunctions collapse and therefore determinate, but still preserve quantum uncertainty. The CSL introduces a quantum noise function that kicks in at some distance from an atom with some very low probability as well.

The CSL seems to be equivalent to the gravitational fluctuations expected due to the motions of atomic charges. Even though such quantum phase fluctuations have not yet been measured, they will be as soon as science gets a few more orders of magnitude of sensitivity. Apparently the LISA Pathfinder noise measurement at L1 still needed a couple of more orders of magnitude of sensitivity to show the CSL effect.

In fact, science has measured CSL quantum phase decay noise, but the chaos of classical Shannon noise so far precludes an unambiguous interpretation. The indeterminate and uncertain quantum phase noise is a part of our universe just as is the determinate Shannon noise of classical chaos.

That fact that very smart people argue about the nature of noise is actually due to the inability of current science to measure quantum phase noise in the background of the classical noise of chaos...but science is getting closer to the truth...

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Robert H McEachern replied on Aug. 6, 2017 @ 18:13 GMT
"The CSL introduces a quantum noise function that kicks in at some distance from an atom with some very low probability as well."

Classically, noise is intrinsic to the very definition of observable information. So there is no need for it to "kick in". It is always present, intrinsic to the entities being observed, because:

Nature does not know how to manufacture truly identical particles. Consequently, the differences between otherwise identical particles, manifest themselves as classical noise, which in turn manifests itself, as the so-called quantum correlations.

Rob McEachern

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Thomas Howard Ray wrote on Sep. 9, 2017 @ 22:13 GMT
I'm looking at the picture 1 /2 |live cat> + 1 / /2 |dead cat> .

If the expression implies an equation, the solution is positive 2. Two equally likely states, life and death.

Are they equally likely?

pp. 7-8

Can one start the Schroedinger cat experiment with a dead cat, and wait an infinitely long time for the result? One knows the result already.

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Robert H McEachern replied on Sep. 10, 2017 @ 19:26 GMT

As I have said many time before, it is the initial conditions and the exploitation of a priori knowledge, not the equations of physics, that dictate the outcome of most events in this world.

Rob McEachern

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Thomas Howard Ray replied on Sep. 10, 2017 @ 23:28 GMT
Rob, I agree.

Unless one deconstructs the equations, however, the case is not convincing.

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Bashir Yusuf wrote on Oct. 11, 2017 @ 01:24 GMT
Dear Steve.

The Gravity and Charge, seems to me to be same natural phenomenon.

You may wonder why?

The answer ia so aimple if you change the way you think into Newtonian Mechanics.

Best wishes.


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Bashir Yusuf wrote on Oct. 11, 2017 @ 02:08 GMT
Dear Scientist!

Are you aware that recently Physics discoveris have the answers of most fundamental questions of science?

And that my theory (essay) in 2010, predicted them, and more other?

But the most serious problem is the way the todays mainstream Physics view the fundamental structure of the Nature.

Since the most fundamental theory (Simple Truth ) is so...

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Joe Fisher wrote on Oct. 11, 2017 @ 14:25 GMT
Dear Bashir Yusuf.

The real earth existed millions of years before real men appeared to live upon its surface. It logically follows that Nature must have produced the only real physical condition allowable.

My Research has concluded that NATURE must have constructed the simplest visible physical Universe obtainable, because reality existed for millions of years before man appeared on earth and started guessing where earth might have came from. The real Universe must consist of only one single unified visible infinite surface occurring eternally in one single infinite dimension that am always illuminated by infinite non-surface light.

Your theory only consists of copied finite misinformation. Isaac Newton only ever produced finite misinformation.

Joe Fisher, ORCID ID 0000-0003-3988-8687. Unaffiliated

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Jason Mark Wolfe wrote on Dec. 21, 2017 @ 06:09 GMT
I'm pretty sure that Schrodinger equation describes energy states, momentum states, places to put energy. Wave functions are probably real things that can't be proven to exist. That's the way it goes.

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