Quantum Darwinism

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Some Quantum Darwinists dream of  a theoretical framework that needs no classical environment, but just shows how classical reality can emerge from mutually interactive  quantum systems!

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In advanced quantum Darwinism experiment, a  nitrogen atom replaces a carbon atom in a diamond.

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Since a nitrogen atom has one more electron than carbon, this excess electron cannot pair up with neighboring carbon electrons to form a chemical bond.

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Since an unpaired electron acts as a lone “spin,” it serves as an arrow pointing up or down.

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A lone spin stays in a superposition pointing  up and/or  down.

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A nitrogen atom’s electron lone spin

can be magnetically coupled to about four carbon-13 spins.

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Carbon-13 atom,  unlike the more abundant carbon-12,  has spin due to an unpaired neutron.

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A nitrogen-vacancy spin is coupled to about four carbon-13 spins within a distance of about 1 nanometer.

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Modern lasers and radio-frequency pulses can register a change in the nitrogen spin  by changes in the nuclear spins of the environmental(carbon-13) atoms.

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In Zurek’s quantum Darwinism experiment, the state of the nitrogen spin is “recorded” as multiple copies in the nuclear spins of the environmental(carbon-13) atoms.

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The information about the nitrogen spin saturates quickly allowing the emergence of classicality as more of the environment is considered.

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Zurek’s quantum Darwinism shows  an internal self-consistency in quantum theory.

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A quantum system imprints replicas of itself on its environment.

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In quantum Darwinism experiments,

only a few particles/ a single photon serves as the quantum system, with a handful of other photons serving as the “environment” that interacts with it and broadcasts information about it.
Some laser photons combine them into multiply entangled groups. Then  the environment photons are interrogated to see what information they encode about the system photon’s pointer state – its polarization (the orientation of its oscillating electromagnetic fields), one of the quantum properties able to pass through the filter of quantum Darwinian selection.

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Since information saturates soon,
measurements of just one of the environment photons reveal a lot of the available information about the system photon’s polarization, and measuring an increasing fraction of the environment photons provided diminishing returns.

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In quantum Darwinism experiments,even a single photon can act as an environment to initiate decoherence and selection if it interacts strongly enough with the lone system photon. When interactions are weaker, a larger environment must be monitored.
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We get a classically objective “position” of a thing because its position state can imprint many identical replicas in the environment.

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An observer can’t monitor more than a fraction of the environment because  the redundancy (repetition of messages to reduce the probability of errors in transmission) of information  quickly saturates.

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Moneymaking mindset looks down upon philosophy. But  quantum physicists  often adopt philosophical interpretations to invent  quantum computers or AI.

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Information about some of the pointer states gets replicated and imprinted on environmental photons in ‘classically accessible format’. So a particular field excitation and its associated fundamental particle can contribute to the formation of atoms,molecules and people.

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Ever since Max Planck proposed quantum theory, physicists have been still trying to reconcile it to Einstein’s relativity.

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“Pointer states”  are measurable properties that researchers can “point” to with a measuring device.

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Pointer states are “sieved and selected” by the environment.

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According to Riedel and Zurek, quantum-information is “copied prolifically into the environment to take on classical-information.

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Since quantum-information is “copied prolifically into the environment, only a small amount of the environment is sufficient to infer the value of the variables. Even a single photon can act as an environment.

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A grain of dust one micrometer across, after being illuminated by the sun for just one microsecond, will have its location imprinted about 100 million times in the scattered photons.

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The redundancy of a particular information(pointer state) imprinted as many identical replicas in the environment creates classical-like properties.

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When photons scatter off an object, we can see it. Photons carry information to our retina in the form of a partial replica of certain pointer states (fundamental measurable properties) about the object, saying something about its position, shape and color.

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Lots of replicas are needed if many observers are to agree on a measured value of some pointer state — a hallmark of classicality. Only lucky pointer states get informationally multiplied in the form of copies imprinted on the environment. Pointer states struggle for classicality. To get imprinted on the environment is enough for their  classicality. Formal observer or measurement is not needed. The entire environment works as an observer.

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In Zurek’s quantum Darwinism, pointer states resemble genes or memes.

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According to Zurek’s quantum Darwinism , our concrete reality condenses(or gets transacted?) from the multiple competing options  residing fundamentally in quantum realm ( or in subjectively inaccessible  Tegmarkian objectivity/entity?).

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Quantum superposition doesn’t really mean that it is in several states at once; rather, it means that if we make a measurement we will see one of those outcomes. Our familiar existential reality is not objectively independent but  transactional/medium-born/ subjective/in-transit/signal-processed.

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An object can exist only  if a

perfectly accurate mathematical description of the universe mathematically allows it to do so. Such a description resembles Tegmark’s  mathematical universe.

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Mere existing might just  be a duality(interchangeability)  for a mathematical tool for making perfectly

accurate predictions, and vice versa. That’s why our existential  reality consists of subjective yes-no questions.

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Zurek’s quantum Darwinism attempts to explain how quantum possibilities can give rise to objective, classical reality.
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The laws of physics arranged by Isaac Newton and Einstein — according to which objects have well-defined positions and properties at all times – don’t work at atomic, subatomic and sub-sub-atomic(planckian) scales.

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At atomic, subatomic and sub-sub-atomic(planckian) scales, classical  concreteness dissolves into a soup of possibilities. An atom has no definite position but the probability of finding it in various places.

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In Zurek’s quantum Darwinism, the definite properties(position, speed, spin direction, etc. ) associated with classical physics get naturally selected from a menu of quantum possibilitie(states) since information about robust states get copied,  transmitted and reproduced   fundamentally by  electromagnetic field and apparently  by environmental photons. Since   information about a quantum system gets repeatedly imprinted on our so-called environments, many independent observers agree on a measured value — a hallmark of classicality!

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Electromagnetic field itself is ‘not a thing’ to be seen but medium/wire/default canvas / picture-tube/channel. Changes or distortions on electromagnetic field propagate as signals to make the the world ‘visible’.

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“The main idea of quantum Darwinism is that we almost never do any direct measurement on anything. [The environment] is like a big advertising billboard, which floats multiple copies of the information about our universe all over the place.”
-W. H.Zurek

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Some quantum states are robust states that can resist decoherence.Such  states have measurable and definite physical quantities like the particle’s velocity and position, equating (or creating?) classical reality. Such states are called ‘pointer states’.

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When  a quantum system interacts with the environment, only its pointer states survive. Such a pointer state  can imprint its “replica” in the environment to build classical reality.Some recent laboratory experiments support quantum Darwinism.

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Charles Darwin’s theory of evolution suggests that nature favors the fittest organism to survive.
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According to quantum mechanics, we should have many realities instead of the one we’re stuck with. Our perceived reality might be the selected one via a quantum form of Darwinism.

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Superposition is the ability of a quantum system to be in multiple states at the same time.
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“Everybody was privileged. There were only privileged people. The others would all be condemned one day. And he would be condemned, too.”

-Albert Camus

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“I don’t know whether this world has a meaning that transcends it. But I know that I cannot know that meaning and that it is impossible for me just now to know it.”

-Albert Camus

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“Nobody realizes that some people expend tremendous energy merely to be normal.”

-Albert Camus

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Only innocence is to be feared.

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“Everything is permitted’ does not mean that nothing is forbidden.”

-Albert Camus

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“Existence is illusory and it is eternal.”

-Albert Camus

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“One recognizes one’s course by discovering the paths that stray from it.”

-Albert Camus

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“A profound thought is in a constant state of becoming; it adopts the experience of a life and assumes its shape.”

-Albert Camus

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“A profound thought might be life itself.”

-Meme Updater

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Quantum-to-classical transition is a riddle at the frontier of physics.

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In traditional quantum decoherence theory, environment is a sink that washes away quantum coherence, suppressing quantum superposition in open quantum system.

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In quantum Darwinism, environment is a strainer that sieves out robust quantum states to build  classical objectivity.

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In quantum Darwinism simulation, many environmental photons are scattered from an observed quantum system. When they are collected, they reveal redundancy of system’s classical information and suppression of quantum correlation in the fragments of environmental photons.

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There is no  fundamental distinction between the familiar macroscopic (classical) and the unfamiliar microscopic (quantum) realms.
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In Wojciech Zurek’s Quantum Darwinism, classical states are actually robust quantum states that survive entanglement during decoherence.

…………………………………………In Zurek’s Quantum Darwinism, information about robust quantum states will be duplicated many times and disseminated throughout the environment. The fittest quantum states will be copied. Copied  states are same to all observers.Thus we get an objective classical reality.
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Quantum world is different from classical one to the extent that no mathematical formalism permits the rigorous passage from one world to another.

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The weirdness of quantum mechanics is telling us something.
But we are still unable to understand it.
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Wheeler used the slogan ‘it from bit’ to mean that the physical universe is made not of matter but of information.
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Quantum theory treats an observation as a yes/no question.
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“Information may not be just what we learn about the world. It may be what makes the world.”-Wheeler
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Even simple collective systems like crystals and waves exhibit causal emergence. Grouping represents a  kind of changes or patterns in monotonous default states .

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Scientists reject all notions of causes except fundamental forces acting between particles.
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Consciousness is an integrated information: bits encoded in the complex networking of neurons, which link together into larger and larger ensembles.
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Quantization of the causal power of brain states represents consciousness at macro scales.
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The best measure of causation is in bits.
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Causation depends on effective or integrated information to influence the future state of a system.
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Effective information belongs to the groups of neurons working as single units.
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A system itself or its description or observation can be viewed as coarse-grained or fine-grained. A kilometre broken into inches has finer granularity than a kilometre broken into metre.
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At a certain macroscopic scale, effective information along with causal power, predictability and consciousness peaks. Further
coarse-graining kills all .
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We’re tuned into the scales of rocks, tsunamis, planets and all other visible  objects evolutionarily because these spatiotemporal quantizations are causally emergent.
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Randomness and redundancy  in the micro or base scales go against any  causal structure.
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Instead of atomic states, a psychological or physiological description can predict an organism’s future situations .It is an example of causal emergence.
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Agency doesn’t exist among the atoms.Causal emergence strengthens agent description.

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Macro states strengthen deterministic causal structure since error-correcting codes in the form of quantization or digitalisation strengthens information channels.Hence, macroscopic entities have greater influence over the future than does the sum of their microscopic components.

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“Codes reduce noise and uncertainty in transmitted data”. — Claude Shannon’s information theory (1948)

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Error-correcting codes in the form of quantization or digitalisation strengthens top-down causation in nature.
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The universe is an information channel.
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Top-down causal structures account for many emergent phenomena such as superconductivity and topological phases of matter.

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Collective systems represent extra causal emergence.

Causal emergence is alien to the reductionist view of nature.
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The relationships between the micro and macro levels of reality come down to the notion of causation.
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Information resides in additional systems (computer memory, piece of paper, etc.) in which copies are stored in an orthogonal product state that has no record of the outcomes.
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Actionable records – information that can be acted upon – reside in orthogonal subspaces of Hilbert space.
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Pure states need to be orthogonal in order to act as originals for (even imperfect) copies. However, one could also use as originals their linear combinations – their superpositions – as long as they are orthogonal.

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Mixed states constitute actionable records –i.e., use their linear combinations as actionable records of something else.

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Only records of outcomes need to be orthogonal, as only they – and not the original quantum states of the microsystem – need to be repeatedly accessible.
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“QD putatively explains, or helps to explain, all of classicality, including everyday macroscopic objects that aren’t in a laboratory, or that existed before there were any humans.”

  • Jess Riedel
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When any two quantum systems  interact, they get “entangled” with each other, entering a shared quantum state in which their possibile properties are interdependent.
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If an atom with a superposition of spin “up” and “down”  collides and gets entangled with an air molecule , both the atom and the air molecule  take on a joint superposition. Different spin means diffrent trajectory for the air molecule.
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With more collisional entanglements   the superposition initially specific to an atom becomes ever more diffuse.
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With ever increasing diffusion, an atom’s superposition decreasingly branches out and superposed states no longer interfere coherently with one another . It looks as though the atom’s superposition has been replaced by a menu of possible classical-like outcomes that no longer interfere with one another. This is the quantum Darwinian explaination of decoherence.
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A typical dust grain floating in the air might lose the superposition in about 10−31 seconds. Even in a vacuum, we can’t look at the grain without destroying its superposition with a photon.

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Quantum systems have some states that are especially robust in the face of disruptive decoherence by the environment.

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Zurek’s robust states are called  “pointer states,” because they can be encoded in the possible states of a pointer on the dial of a measuring instrument.
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The process by which nuclear spin decoherence gives rise to classical objectivity is the same as that occurs due to photons in our macroscopic world.

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Quantum superpositions are embedded in a much larger environment, initially out of equilibrium.
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Environment selects certain preferred
states, and proliferates accessible information about them into the world,
keeping non-redundant quantum correlations to the dustbin of inaccessibility.
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Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system.
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Quantum Darwinism explains how the fragility of a state of a single quantum system can lead to the classical robustness of states of their correlated multitude.
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Quantum Darwinism shows how effective ‘wavepacket collapse’ arises as a result of proliferation throughout the environment of imprints of the states of quantum system; and provides a framework for the derivation of Born’s rule suggesting that the right way to interpret the wavy nature of quantum particles is as waves of probability.
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In quantum Darwinism,  particles leave imprints on their environment and what we experience as reality is the observation of copies of these imprints.
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In our  classical world,  we’re either here or there, but never both. In quantum mechanics , a particle can exist in more than one simultaneous state.

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In our  classical world, we can look at the same thing a billion times and it won’t suddenly become something else.
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In our  classical world, we can’t “use up all our observations” of a thing. In quantum world, particles exist in multiple states and when we interfere with them by merely observing or trying to measure them, it causes them to collapse into the state we see.
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“How is it then possible that objects we deal with [in the classical world] can be safely observed, even though their basic building blocks are quantum?”

Zurek

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In Zurek’s quantum Darwinism, our apparent classical world is an  emergence  from the fundamental  quantum substrate of our Universe.
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Zurek’s quantum Darwinism shows the role of the environment in the transition from quantum to classical.
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In Zurek’s quantum Darwinism, pointer states are the preferred sets of states that define our everyday classical reality.
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In Zurek’s quantum Darwinism, pointer states emerge as a result of the breaking of the unitary symmetry of the Hilbert space which happens when the unitarity of quantum evolutions encounters nonlinearities inherent in the process of amplification—of replicating information.

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In Zurek’s quantum Darwinism, pointer states determine and define events—without appealing to Born’s Rule for probabilities.
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The entanglement-assisted invariance, or envariance is the  symmetry of entangled quantum states.

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In Zurek’s quantum Darwinism,

information flows are responsible for decoherence.

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In Zurek’s quantum Darwinism, information flows are responsible for  the perception of objective classical reality.

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In Zurek’s quantum Darwinism, the effective amplification that information flows represent accounts for the objective existence of the einselected states of macroscopic quantum systems through the redundancy of pointer state records in their environment.

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Even theoretical foundations of quantum mechanics have an impact on contemporary society.

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In Zurek’s quantum Darwinism, observers perceive the state of the ‘rest of the Universe’ relative to their own state, or—to be more precise—relative to the state of their records. Thus, it avoids a ‘many worlds’ ontology.
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It is a great mistake to expect that a single idea should provide a complete solution.
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Explaining reality calls for several ideas  in the right order.

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Bohr’s quantum theory initially needs a classical domain.

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A  fully quantum Universe has  effectively classical but ultimately quantum states to  define what exists—branches of the universal state vector.
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Without a preferred basis, relative quantum states are just ‘too relative’, and Zurek’s relative state approach suffers from basis ambiguity.
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In open quantum systems, only certain quantum states retain stability in spite of the immersion of the system in the environment.
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In Zurek’s quantum Darwinism,  superpositions are unstable, and quickly decay into mixtures of the einselected, stable pointer states.
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Einselection is environment-induced superselection.

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In Zurek’s quantum Darwinism,  Born’s Rule can be derived from entanglement-assisted invariance, or envariance—from the symmetry of entangled quantum states.
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In Zurek’s quantum Darwinism,  envariance is a purely quantum symmetry, as it is critically dependent on the telltale quantum feature—entanglement.

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In Zurek’s quantum Darwinism,  envariance is a purely quantum symmetry that explains the origin of probabilities relevant for statistical physics and thermodynamics.
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In Zurek’s quantum Darwinism,  the fundamental derivation of objective probabilities allows one to discuss information flows in our quantum Universe, and hence understand how the perception of classical reality emerges from the quantum substrate.

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In Zurek’s quantum Darwinism, even preferred quantum states defined by einselection are still ultimately quantum.
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In Zurek’s quantum Darwinism, preferred quantum states can be found out without getting disrupted by initially ignorant observers through direct measurement by upgrading the role of the environment.

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In traditional decoherence theory, the environment is the collection of degrees of freedom where quantum coherence (and hence phase information) is lost.
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In Zurek’s quantum Darwinism,  the environment plays the role of a witness to the state of the system of interest, and a communication channel through which the information reaches us, the observers.

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While temperature is an average measure of motion, time is a cumulative measure of motion.

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Wojciech Zurek, in his ‘Quantum Darwinism’, attempts to explain why we have one reality instead of many quantum states or possibilities.

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Though things aren’t fluctuating in and out of existence in our  consistent reality ,a particle fundamentally exists in quantum superposition- in a range of possible states.
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The main idea of quantum Darwinism is that it’s how the system is interacting with its environment that causes decoherence, rather than the observation of it.
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The ubiquity (the state of being everywhere at once) of environmental influences is why we don’t see big objects to stay  in quantum states.

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Zurek says that quantum systems exhibit “pointer states” – characteristics like a particle’s location or speed that can be measured.
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During interactions with the environment around it, a particle’s superpositions (like alternative speeds or locations) decohere, with only the pointer state remanning.
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“Pointer state” is the state we can observe as it “imprints” its replica on the environment.
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Only the “fittest” state that is best adapted for the environment will come out of decoherence. Hence, Zurek’s theory is called quantum  Darwinism.
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“The main idea of quantum Darwinism is that we almost never do any direct measurement on anything.”

Dr. Wojciech Zurek

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“[The environment] is like a big advertising billboard, which floats multiple copies of the information about our universe all over the place.”

Dr. Wojciech Zurek

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Ever since Max Planck proposed quantum theory, physicists have tried to unify classical physics and quantum physics.
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Classical physics and quantum physics seemingly operate under very different sets of rules.
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The unreal workings of quantum mechanics can give rise to a tangible universe.

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In superposition, a particle can exist in a variety of quantum states. But this isn’t to say that the particle is in all these states at once.
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Superposed states are like waves rolling into a rocky beach and interacting with one another. However, once a single surfer pops  up on one of those waves, other waves disappear.
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Quantum particles always interact  with their environment.
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Particles existed before human beings were around to observe them.
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Zurek’s quantum Darwinism , at least theoretically, explains everyday macroscopic objects that aren’t in a laboratory, or that existed before there were any humans.

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Quantum Darwinism (QD) is a informationtheoretic explanation for objective reality independent of any observer.

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Quantum Darwinism attempts to unify  the works of Darwin, Einstein, and Hawking.
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In Zurek’s quantum Darwinism, reality is just the imprint left behind from quantum dices giving birth to random but robust  possibilities  like  particles, universes or  lucky observers  like us.
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In Zurek’s quantum Darwinism, our  familiar classical world is just the tip of  a quantum world. Classical physical quantities  are analogically surface level waves on a quantum sea.
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In Zurek’s quantum Darwinism, forms  are just dualistically physical expression of robust physical quantities ( possible quantum states).

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In Zurek’s quantum Darwinism, information about ‘randomly robust’ quantum states proliferates throughout the world via the environment (already entangled or diffused states ).

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In Zurek’s quantum Darwinism, redundantly imprinted information is independently accessible by ‘many already entangled or diffused states’ described well with umbrella terms like  ‘environment’ or ‘observer’.
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In Zurek’s quantum Darwinism, the objective classical world emerges from the underlying quantum substrate.

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In Zurek’s quantum Darwinism, the environment is a communication channel selectively acquiring information about the system’s decoherence-resistant pointer states to transmit it to observers.

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In Zurek’s quantum Darwinism, an initial quantum superposition
of pointer spin states, turns  into a product state with the environment spins. The superposition in the system actually “branches out” into
the environment, creating correlations with other
spins.
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Each environment spin holds a perfect record of the pointer state, i.e.  the conditional states.

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The quantum correlation between
the electronic spins and the nuclear spins is used in  the experiments of  quantum Darwinism.

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