A boost for quantum reality
May 9, 2012 | Source: Nature News
The authors show that wavefunctions are real physical states with a joint measurement on n qubits, with the property that each outcome has probability zero on one of the input states. Such a measurement can be performed by implementing the quantum circuit shown above. (Credit: Matthew F. Pusey, Jonathan Barrett, Terry Rudolph)
In a controversial paper in Nature Physics, theorists claim they can prove that wavefunctions — the entity that determines the probability of different outcomes of measurements on quantum-mechanical particles — are real states.
The paper is thought by some to be one of the most important in quantum foundations in decades. The authors say that the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.
Matt Leifer, a physicist at University College London who works on quantum information, says that the theorem tackles a big question in a simple and clean way. He also says that it could end up being as useful as Bell’s theorem, which turned out to have applications in quantum information theory and cryptography.
But it’s incompatible with quantum mechanics, so the theorem also raises a deeper question: could quantum mechanics be wrong?
Ref.: Matthew F. Pusey, Jonathan Barrett, Terry Rudolph, On the reality of the quantum state, Nature Physics, 2012, DOI: 10.1038/nphys2309
Ref.: Matthew F. Pusey, Jonathan Barrett, Terry Rudolph, On the reality of the quantum state, 2011, arXiv:1111.3328v2
Comments (13)
by Gav
The problem is someone’s mind is not compatible
by cosmowrench
Didn’t the double slit experiment prove that waves are real? I thought there wasn’t any doubt about that. I mean, you shoot a single particle over and over at the slits and an interferance pattern shows up. What more proof do you need?
by Mattinblack
I see you are a victim of wave/particle discontinuity. Light is BOTH a wave of probabilitty and a physical particle. If you detect which slit a photon is going to pass through then the interference pattern disappears. Turn the detector off, but leave everything the same then the pattern reappears. As one early quantum physicist remarked in despair… But how does it KNOW?
by eldras
:) it looks like that form human perspectives. If you look at the world as waves everything works thru. Waves are one vibration, we haven’t scratched the surface of reality i think. But the quantum world has been returned to cause and effect with Hugh Everett’s work.
by Phil Tyson
How can waves exsist without particals. Show me a wave that isn’t made up of particals of some description. Even if the particals don’t act as we think they should to be called particals does this mean if there’s enough of them they can’t form a wave?
by George
waves in normal circumstances do NOT exist with particles.
for example electromagnetic waves.
The waves you are thinking of such as ocean waves and sound waves are not actually waves but sequences of collisions that APPEAR like waves.
by Novalis
I agree with the jist of your argument. Except photons are wave packets in electric and magnetic fields. I don’t think any waves we know of don’t have a medium.
by dougw659
The answer to both questions is pretty simple, but one which most scientists and physicists don’t want to address. We do, in fact experience the wave function. There IS in fact both an alive and a dead cat after a Schrodinger experiment. The medium of the wave is the millions (or more) of particles that exist in slight variations of space-time that are the ‘Multiverse’ spoken of by people like David Deustch and others. As Deustch points out in his most recent book, “The Beginning of Infinity” results of quantum computing alone prove that there MUST be other particles involved in the solving of the equations. the fact that we can not easily interact with those particles is no reason to deny their existence. But we DO interact with them on incredibly small levels, when we do things like quantum computing, or double slit experiments, or other quantum-level tasks. We reject the notion of the existence of these particles only because we don’t like the implications, that perhaps ‘we’ are not so unique, that perhaps millions or more copies of our consciousness also exist across the Multiverse. We don’t like the thought that one of us pulls a live cat out of a Schrodinger box while another winces as we see the dead animal inside that box, and that the two versions of ‘us’ can not interact in a way we currently can measure.
by George
WE not only interact with them on a experimental level – every cell of our body actively manipulates the quantum waves they exist in as they drag protons and electrons along predefined paths to make the chemical reaction reality that forms the material out of the quantum wave multiverse.
YOUR cells are materially measuring – and thus forming – the quantum waves multiverse and thereby creating the material they are made of millions of times a second at the atomic level.
An enzyme for example is a specific molecule which specifically manipulates the quantum waves multiverse to produce the particle needed along a continuous pathway in time-space to deliver the needed proton or electron or molecule to the needed time space destination for that needed thing.
by Mortran
How comes that we don’t experience the wave function then? We can only experience distinct states.
Just let me bring back the example of “Schroedinger’s cat”. You don’t see a half-dead/half-alive cat statistically distributed in the cage. You see either a dead or a living cat.
by George
the multiverse “you” doesn’t just experience one specific state. You are only living in one specific state that your are conscious of in the time line. You are simultaneously living and experiencing every other possible time line.
It’s like a camera with a colored filter. the film experiences all wavelengths however the colored tinted photo made with a filter (you in this multiverse) only experiences the filter multiverse that it tunes with it’s filters at that time.
your body your consciousness is awar eof at any given time is one that is filtered by it’s mutliverse filter.
This is not mumbo jumbo. It’s the way the universe works.
Your current consciousness is experiencing the quantum universe like a man with tightly narrow field glasses. . it doesn’t mean the rest of the “world” isn’t out there. It just means your particular configuration is only seeing a small part of it at one time.
by Novalis
If the wavefunction is real, what is the medium for the wave? All waves seem to have a medium. If the wave is not merely a statistical tool, wouldn’t the wave require a medium?
by George
you have it backwards. MAterial isn’t reality. the waves are reality. the sense of a material “thing” is what is “felt” or resolved when youy put another wave pattern in front of the other waves.
A two dimensional example is two crossing boat wakes make a higher point where they meet on the surface of the water.
Imagine that in three d space and you see how a “aporticle” can Seem to physically exist when you are merely feeling the force exerted by a intersection of waves.
Now I know your a thinking “water is real” but actually think of those molecules as atoms which are really tiny magenetic like waves exerting forces on each other like holding two north poles of two magnets near each other – they don’t actually pysically exist but the resiostance forces you “feel” when they interact make you “think” they “exist”.
On a small scale all large materials are merely the aligned interactions of tiny atomic forces of particles that don’t really exist but exert forces on each other through the combination of their wave forces.
(actually 5d is the correct number) of dimensions as well