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originally posted by: PhyllidaDavenport
Surely this is just another wave/particle observer effect carried out years ago? Sounds exactly the same regurgitated
originally posted by: PhyllidaDavenport
Surely this is just another wave/particle observer effect carried out years ago? Sounds exactly the same regurgitated
Consider a single photon in a superposition of horizontal |hi and vertical polarization |vi, measured in the h, v basis by an observer—Wigner’s friend—in an isolated lab, see Figs. 1a and b. According to quantum theory, the friend randomly observes one of the two possible outcomes in every run of the experiment. The friend’s record, h or v, can be stored in one of two possible orthogonal states of some physical memory, labeled either |“photon is h”i or |“photon is v”i, and constitutes a “fact” from the friend’s point of view. Wigner observes from outside the isolated laboratory and has no information about his friend’s measurement outcome. According to quantum theory Wigner must describe the friend’s measurement as a unitary interaction that leaves the photon and friend’s record in the entangled state (with implicit tensor products):
Wigner can now perform an interference experiment in this entangled basis to verify that the photon and his friend’s record are indeed in superposition—a “fact” from his point of view, from which he concludes that his friend cannot have recorded a definite outcome. Concurrently however, the friend does always record a definite outcome, which suggests that the original superposition was destroyed and Wigner should not observe any interference. The friend can even tell Wigner that she recorded a definite outcome (without revealing the result), yet Wigner and his friend’s respective descriptions remain unchanged [6]. This calls into question the objective status of the facts established by the two observers. Can one reconcile their different records, or are they fundamentally incompatible—so that they cannot be considered objective, observer-independent “facts of the world”
Once the person in the lab measures the photon, the particle assumes a fixed polarization. But for someone outside that closed laboratory who doesn't know the result of the measurements, the unmeasured photon is still in a state of superposition.
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Alice and Bob could arrive at conclusions about the photons that were correct and provable and that yet still differed from the observations of their friends — which were also correct and provable, according to the study.
originally posted by: Woodcarver
a reply to: neoholographic
The universe is not quantum though. Quantum is a specific scale of observation. It is a scale where regular physics does not apply. The scale that you and I can observe from has been shown to react in a way that could be described by what we would call general physics.
Everything is quantum, however the reason quantum behaviors are not typically observed on everyday human scales is because decoherence causes the quantum system to effectively behave like a classical system. The idea is in one sentence from this abstract proposing an advancement in the theory:
originally posted by: neoholographic
Why wouldn't the universe be quantum if all is quantum? Like I said, I don't think you know what that means. This is why you haven't answered any questions I've asked you 3 times now.
Now, the quantum to classical transition is considered to occur via decoherence caused by stochastic interaction with an environment.
Do you have calculations or experimental measurements to back that up?
originally posted by: neoholographic
Like I said in another thread, this would be a small but noticeable effect.
In particular, according to a study released Monday in Nature Chemistry, an international team of scientists showed that molecules involved in photosynthesis display quantum mechanical behavior. Even though we’d suspected as much before, this is the first time we’ve seen quantum effects in living systems. Not only will it help us better understand plants, sunlight and everything in between, but it could also mean cool new tech in the future.
You might have heard of Schrödinger’s Cat, which is both alive and dead at the same time thanks to quantum weirdness — in particular, because electrons can be in two states at the same time. It’s only when we observe the system that the weirdness collapses and reality “picks” one state: the cat’s actually alive (or dead), the electron’s actually at this end of the room (or that end).
But quantum effects are typically limited to the very small, and only really observable in perfect, laboratory conditions. A living being, with its wet, messy systems, would be a tough place to find some quantum weirdness lurking — and yet we have.
Scientists zoomed in on the Fenna-Matthews-Olson (FMO) complex, a key component of green sulfur bacteria’s machinery for photosynthesis. It’s been a historical favorite for such research because we’ve long known its structure and it’s fairly easy to work with.
And observe it they did! With a technique called two-dimensional electronic spectroscopy, researchers saw molecules in simultaneous excited states — quantum weirdness akin to a cat being alive and dead at the same time. What’s more, the effect lasted exactly as long as theories predicted it, suggesting this evidence of quantum biology will last. As the authors succinctly put it, “Thus, our measurements provide an unambiguous experimental observation of excited-state vibronic coherence in the FMO complex.”
As little as a decade ago, scientists were sure that the chemistry of life and the weird chemistry of the quantum world were completely separate things. Quantum effects were usually observed only on the nanometer scale, surrounded by hard vacuum, ultra-low temperatures, and a tightly controlled laboratory environment. Biology, however, is a macroscopic world that is warm, messy, and anything but controlled. It seemed elementary that a quantum phenomenon such as 'coherence', in which the wave patterns of every part of a system stay in step, wouldn't last a microsecond in the tumultuous realm of the cell. It would be simply unthinkable.
Or so we thought…
Recent years have seen scientists finding coherent quantum processes all across the natural world. And it’s not just in some exotic halobacteria or flying marsupial, it turns out quantum biology is pretty much ubiquitous. In fact, it appears to be a central part in the most important chemical reactions on Earth: photosynthesis and cellular respiration.
A recent experiment may have placed living organisms in a state of quantum entanglement
The cells were harvested after 3 days of cultivation, by centrifugation at 6000 g, resuspended and broken using EmulsiFlex C5 (Avestin Inc., Canada) at 20000 psi. Unbroken cells were removed by low speed centrifugation and the membrane fragments present in the resulting supernatant were collected by ultracentrifugation at 200000 g for 2 hours and then resuspended in isolation buffer. FMO was released from membranes by 0.4 M Na2CO3 added in two steps over the course of 2 days (at 4 ◦ C in the dark) to release FMO. The soluble protein fraction was cleared of debris by ultracentrifugation, dialysed against the isolation buffer for 72 hours, concentrated and purified using size exclusion and anion exchange chromatography until OD271 / OD371 ratio decreased below 0.6. Prior 2DES experiments the sample was dissolved in a 2:1 glycerol:buffer solution, and was held at 77K in a nitrogen flow cryostat during the entire experiment.
They did not show how much of a role it plays at 77K because they didn't measure any photosynthesis at 77K nor did they calculate or measure or otherwise show how much it contributes to photosynthesis.
originally posted by: neoholographic
They found that quantum beats from vibrational coherence were long enough to play a role in photosynthesis.
Does it need to be 77k for photosynthesis to occur?
So then, is photosynthesis “quantum” or not? “The observations show that there is correlation between the wavefunctions of the states involved in energy or electron transfer,” says Romero. “But these effects are not considered by some scientists as truly quantum coherence in the sense that entangled states of quantum computing are understood.” And Engel agrees that to compare the two is to invoke “the wrong language”.
Miller argues that the strength of the vibrational coupling is far too low to enhance energy transport. He sees an imprint of evolved optimality in the very absence of quantum coherence – in the fact that it is very rapidly lost after photo absorption through decoherence. “It turns out that nature has evolved to not beat decoherence but exploit it,” he says. It’s precisely because decoherence causes the dissipation of energy that the energy transfer can find its way gradually downhill along the most energy-efficient path, guided by how electronic properties vary from place to place in the molecular environment...
maybe these correlations and coherences, mediated by vibrations, are in any case too weak to have any biological relevance, and we still have to think of exciton states in the photosystem as being more or less localized to particular molecular groups, with incoherent transfer of energy between them. That’s what Miller and Thorwart think. “We have come full circle,” Miller says, “and it seems that the early picture of energy transport as a largely incoherent process has withstood the challenge.”
Photons can have quantum entanglement but they have never been measured to have any charge so it's generally presumed they don't, or if they do, it's too small to measure.
originally posted by: blackcrowe
Is QE a relationship between particles?
Or.
Is it a relationship between charges from "particles"?
Oh my #ing god!!!
Decoherence has been used to understand the collapse of the wave function in quantum mechanics. Decoherence does not generate actual wave-function collapse. It only provides an explanation for the observation of wave-function collapse, as the quantum nature of the system "leaks" into the environment. That is, components of the wave function are decoupled from a coherent system and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the "realization" of precisely one state in the "ensemble".
We find that although calculations predict a prolongation of this coherence due to vibronic coupling, the combination of dynamic disorder and vibrational relaxation leads to a coherence decay on a timescale comparable to the electronic dephasing time.
Yet Scholes concedes that his new results do support the original contention that “the molecules in the FMO protein are coupled in a special way and this may aid energy transport by directing it or making it quicker”. According to Romero, this tuning of molecular vibrations to the right frequencies for transferring energy makes the photosystem what she calls a “quantum-designed light trap”. When you look at photosynthetic reaction centres for a range of organisms, she says, “there is only one design that is conserved, which suggests that nature has found a design able to perform efficient charge separation and has maintained it”. In other words, she says, natural selection seems to have favoured this quantum-optimized process.