Quantum Darwinism
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Quantum Darwinism is a theory meant to explain the emergence of the
A study in 2010 is claimed to provide preliminary supporting evidence of quantum Darwinism with scars of a quantum dot "becoming a family of mother-daughter states" indicating they could "stabilize into multiple pointer states";[3] additionally, a similar kind of scene has been suggested with perturbation-induced scarring in disordered quantum dots[4][5][6][7][8] (see scars). However, the claimed evidence is also subject to the circularity criticism by Ruth Kastner (see Implications below). Basically, the de facto phenomenon of decoherence that underlies the claims of Quantum Darwinism may not really arise in a unitary-only dynamics. Thus, even if there is decoherence, this does not show that macroscopic pointer states naturally emerge without some form of collapse.
Implications
Along with Zurek's related theory of envariance (invariance due to quantum entanglement), quantum Darwinism seeks to explain how the classical world emerges from the quantum world and proposes to answer the quantum measurement problem, the main interpretational challenge for quantum theory. The measurement problem arises because the quantum state vector, the source of all knowledge concerning quantum systems, evolves according to the Schrödinger equation into a linear superposition of different states, predicting paradoxical situations such as "Schrödinger's cat"; situations never experienced in our classical world. Quantum theory has traditionally treated this problem as being resolved by a non-unitary transformation of the state vector at the time of measurement into a definite state. It provides an extremely accurate means of predicting the value of the definite state that will be measured in the form of a probability for each possible measurement value. The physical nature of the transition from the quantum superposition of states to the definite classical state measured is not explained by the traditional theory but is usually assumed as an axiom and was at the basis of the debate between Niels Bohr and Albert Einstein concerning the completeness of quantum theory.
Quantum Darwinism seeks to explain the transition of quantum systems from the vast potentiality of superposed states to the greatly reduced set of
As a quantum system's interactions with its environment results in the recording of many redundant copies of information regarding its pointer states, this information is available to numerous observers able to achieve consensual agreement concerning their information of the quantum state. This aspect of einselection, called by Zurek 'Environment as a Witness', results in the potential for objective knowledge.
Darwinian significance
Perhaps of equal significance to the light this theory shines on quantum explanations is its identification of a Darwinian process operating as the selective mechanism establishing our classical reality. As numerous researchers have made clear any system employing a Darwinian process will evolve. As argued by the thesis of Universal Darwinism, Darwinian processes are not confined to biology but are all following the simple Darwinian algorithm:
- Reproduction/Heredity; the ability to make copies and thereby produce descendants.
- Selection; A process that preferentially selects one trait over another trait, leading to one trait being more numerous after sufficient generations.
- Variation; differences in heritable traits that affect "Fitness" or the ability to survive and reproduce leading to differential survival.
Quantum Darwinism appears to conform to this algorithm and thus is aptly named:
- Numerous copies are made of pointer states
- Successive interactions between pointer states and their environment reveal them to evolve and those states to survive which conform to the predictions of classical physics within the macroscopic world. This happens in a continuous, predictable manner; that is descendants inherit many of their traits from ancestor states.
- The analogy to the Variation principle of "simple Darwinism" does not exist since the Pointer states do not mutate and the selection by the environment is among the pointer states preferred by the environment (e.g. location states).
From this view quantum Darwinism provides a Darwinian explanation at the basis of our reality, explaining the unfolding or evolution of our classical macroscopic world.
Notes
- S2CID 119205282.
- ^ S2CID 14759237. Archived from the original(PDF) on February 21, 2009. Retrieved 2008-08-05.
- PMID 20482124.
- Lisa Zyga (May 10, 2010). "New evidence for quantum Darwinism found in quantum dots". Phys.org.
- S2CID 208248295.
- PMID 27892510.
- S2CID 119083672.
- S2CID 51693305.
- ISBN 978-952-03-1699-0.
- S2CID 20719455.
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References
- S. Haroche, J.-M. Raimond, Exploring the Quantum: Atoms, Cavities, and Photons, Oxford University Press (2006), ISBN 0-19-850914-6, p. 77
- M. Schlosshauer, Decoherence and the Quantum-to-Classical Transition, Springer 2007, ISBN 3-540-35773-4, Chapter 2.9, p. 85.
- Zurek, Wojciech Hubert (2009). "Quantum Darwinism". Nature Physics. 5 (3): 181–188. S2CID 119205282.
- Blume-Kohout, Robin; Zurek, W. H. (2006). "Quantum Darwinism: Entanglement, branches, and the emergent classicality of redundantly stored quantum information". Physical Review A. 73 (6): 062310. S2CID 11786634.
- Zurek, W. H. (2003). "Quantum Darwinism and Envariance". arXiv:quant-ph/0308163.
- Blume-Kohout, Robin; Zurek, W. H. (2006). "Quantum Darwinism: Entanglement, branches, and the emergent classicality of redundantly stored quantum information". Physical Review A. 73 (6): 062310. S2CID 11786634.
- Ollivier, Harold; Poulin, David; Zurek, Wojciech H. (2005). "Environment as a Witness: Selective Proliferation of Information and Emergence of Objectivity in a Quantum Universe". Physical Review A. 72 (4): 042113. S2CID 56301210.
- Zurek, W. H. (2005). "Probabilities from Entanglement, Born's Rule from Envariance". Physical Review A. 71 (5): 052105. S2CID 18210481.
- Wojciech Hubert Zurek (2018). "Quantum theory of the classical: Quantum jumps, Born's Rule and objective classical reality via quantum Darwinism". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 376 (2123). PMID 29807905.
- Wojciech Hubert Zurek (2007). "Relative States and the Environment: Einselection, Envariance, Quantum Darwinism, and the Existential Interpretation". ].