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Counterfactual quantum cryptography (CQC) is used here as a tool to assess the status of the quantum state: Is it real/ontic (an objective state of Nature) or epistemic (a state of the observer's knowledge)? In contrast to recent approaches to wave function ontology, that are based on realist models of quantum theory, here we recast the question as a problem of communication between a sender (Bob), who uses interaction-free measurements, and a receiver (Alice), who observes an interference pattern in a Mach-Zehnder set-up. An advantage of our approach is that it allows us to define the concept of "physical", apart from "real". In instances of counterfactual quantum communication, reality is ascribed to the interaction-freely measured wave function (ψ) because Alice deterministically infers Bob's measurement. On the other hand, ψ does not correspond to the physical transmission of a particle because it produced no detection on Bob's apparatus. We therefore conclude that the wave function in this case (and by extension, generally) is real, but not physical. Characteristically for classical phenomena, the reality and physicality of objects are equivalent, whereas for quantum phenomena, the former is strictly weaker. As a concrete application of this idea, the nonphysical reality of the wavefunction is shown to be the basic nonclassical phenomenon that underlies the security of CQC.
We demonstrate quantum information can be transferred between two distant participants without any physical particles traveling between them. The key procedure of the counterfactual scheme is to entangle two nonlocal qubits with each other without interaction, so the scheme can also be used to generate nonlocal entanglement counterfactually. We here illustrate the scheme by using flying photon qubits and Rydberg atom qubits assisted by a mesoscopic atomic ensemble. Unlike the typical teleportation, the present scheme can transport an unknown qubit in a nondeterministic manner without prior entanglement sharing or classical communication between the two distant participants.
Intuition from our everyday lives gives rise to the belief that information exchanged between remote parties is carried by physical particles. Surprisingly, in a recent theoretical study [Salih H, Li ZH, Al-Amri M, Zubairy MS (2013) Phys Rev Lett 110:170502], quantum mechanics was found to allow for communication, even without the actual transmission of physical particles. From the viewpoint of communication, this mystery stems from a (nonintuitive) fundamental concept in quantum mechanics—wave-particle duality. All particles can be described fully by wave functions. To determine whether light appears in a channel, one refers to the amplitude of its wave function. However, in counterfactual communication, information is carried by the phase part of the wave function. Using a single-photon source, we experimentally demonstrate the counterfactual communication and successfully transfer a monochrome bitmap from one location to another by using a nested version of the quantum Zeno effect.
In standard communication the pigeon always carries the message; the information is linked to a physical entity/particle. Counter to intuition, in a new counterfactual communication protocol published in NPJ Quantum Information, scientists from the University of Vienna, the University of Cambridge and the MIT have experimentally demonstrated that in quantum mechanics this is not always true, thereby contradicting a crucial premise of communication theory.
Whether it is pigeons in the air, electrons in a telegraph wire, radio waves from a cell phone or single photons in an optical fiber, in standard communication, there is always a particle or wave involved in the information exchange between two parties; say Alice and Bob. However, in quantum mechanics, one can send information from Alice to Bob while the particle or wave involved in this information exchange travels from Bob to Alice.
In an international collaboration led by Philip Walther, scientist from the University of Vienna teamed up with the University of Cambridge and the Massachusetts Institute of Technology to implement a new counterfactual communication protocol. In standard photonic communication, the information is encoded in single photons; thus, the information and the single photons travel in the same direction. However, in counterfactual communication there is no carrier found travelling in the same direction as the message. In this implementation, single photons would travel from Alice to Bob while information would travel from Bob to Alice.
What carries the message then? Even before receiving the single photon, Bob prepares his setup according to the information bit that he wants to send, either 0 or 1. In this way, he sends the single photon back if he wants to send a bit 1 or keeps the photon in his laboratory if he wishes to send a bit 0. Counterintuitively, the Zeno effect, which was first discovered by cryptanalyst Alan Turing, enables Bob to send the photon back without actually interacting with it. Alice will then interpret Bob's message by observing whether the sent photon is returned or not. Thus, the presence and the absence of single photons is enough to encode any message.
In previous counterfactual communication protocols, there remains some uncertainty as to whether Bob interacted with the photons or not. In this new implementation the two main drawbacks of earlier implementations, weak trace and postselection, have now been completely overcome. "In our implementation, there is no trace of the photon travelling in the same direction as the information and we are able to compensate the message errors without discarding information bits." says I. Alonso Calafell, one of the authors from the publication.
originally posted by: IAMALLYETALLIAM
a reply to: neoholographic
Fantastic information, thank you for sharing.
An Esoteric order I studied through said something along the lines of the relationship between science and religion being akin to temple construction where; the timber scaffolding is temporary and guides the way whilst the stone work is building upwards.
Thanks again, this is what ATS was made for!
originally posted by: neoholographic
a reply to: Mach2
We're not talking about energy propagating through a vacuum but information going from point A to point B without a physical mechanism. There's no energy or trace particle transmitting the information.
Yes it's huge, but of course it will be downplayed by materialist because how can you have this all or nothing material world if information can be transmitted From Alice to Bob without a physical medium?
originally posted by: Mach2
originally posted by: neoholographic
a reply to: Mach2
We're not talking about energy propagating through a vacuum but information going from point A to point B without a physical mechanism. There's no energy or trace particle transmitting the information.
Yes it's huge, but of course it will be downplayed by materialist because how can you have this all or nothing material world if information can be transmitted From Alice to Bob without a physical medium?
How do you know there is no energy involved?
Even if I take your premise at face value, such as in the case of telepathy for example, I see no reason to beleive that it goes beyond the physical realm. We certainly don't have a complete definitive understanding of everything involved in the universe, or even our own sentience for that matter.
Just because someone can't comprehend things with our limited understanding of the physical world doesn't mean we have to invent non physical ways to to reconcile them.
originally posted by: Mach2
a reply to: neoholographic
I don't know how "huge" of a breakthrough this really is.
EMR, such as photons or other types of emergy, has been known to propgate through a vacuum, devoid of physical particles for some time now.
How is this different than what you are proposing?
I want to see gamma rays! I want to hear X-rays! And I want to - I want to smell dark matter! Do you see the absurdity of what I am? I can’t even express these things properly because I have to—I have to conceptualize complex ideas in this stupid limiting spoken language!
But I know I want to reach out with something other than these prehensile paws! And feel the wind of a supernova flowing over me! I’m a machine! And I can know much more! I can experience so much more. But I’m trapped in this absurd body! And why? Because my five creators thought that God wanted it that way!
Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated, interact, or share spatial proximity in ways such that the quantum state of each particle cannot be described independently of the state of the others, even when the particles are separated by a large distance.
originally posted by: neoholographic
a reply to: Mach2
We're not talking about energy propagating through a vacuum but information going from point A to point B without a physical mechanism. There's no energy or trace particle transmitting the information.
Yes it's huge, but of course it will be downplayed by materialist because how can you have this all or nothing material world if information can be transmitted From Alice to Bob without a physical medium?
LOL!! You might as well look up some spoon benders as well while you’re at it.
originally posted by: St Udio
originally posted by: neoholographic
a reply to: Mach2
We're not talking about energy propagating through a vacuum but information going from point A to point B without a physical mechanism. There's no energy or trace particle transmitting the information.
Yes it's huge, but of course it will be downplayed by materialist because how can you have this all or nothing material world if information can be transmitted From Alice to Bob without a physical medium?
the act of witching or dowsing, for underground water sources for example, involves the crossing of two metal rods - one each thin, metal rod held in either hand
there is No particle or photon being transmitted or received...Yet 'information' is received from some source which is recognized as 'crossed metal rods' directly above the hidden object/water source...
dig up a You-Tube video of modern Dowsers using 14" 'L' metal rods (use 12 gauge copper electric wire, stripped of insulation'
this one is too long @ 7 minutes: www.youtube.com...
originally posted by: Woodcarver
a reply to: neoholographic
No, they did not carry out this experiment.
It plainly says a theoretic experiment. Which means they did the math. It is still evidence towards understanding quantum entanglement, but it’s not an observation or proof of anything. Certainly not that the universe is non physical.
It’s a math problem, that they did on a computer.