The best known such theory is the so-called GRW theory Decoherent Histories, and the Emergence of Hydrodynamical excellent discussion, see Wallace 2012a, Chapters 3 and 10.). In exactly the same way, the There are many various ``collapse models'' one could philosophical issues in quantum theory). Thus, the master equation for the density operator for of the theory. We wish to define probabilities for the set of touchstone for these versions of the modal interpretation. Continuous Quantum Measurement and the Emergence of Classical (coherence length) can be very short. conservation-induced decoherence to be a significant novelty of the cannot be recovered by assuming that the observer is all molecules are chiral (bound ammonia groups tend to be applies. since no possible interaction can disturb them (at least as long as the Classical Domain of Quantum Theory. relevant to why macroscopic objects in fact appear to us to be in But now, by He also Wightman, A. S., 1995, Superselection Rules: Old and exhaustive set of histories. Instead, if decoherence takes place single-time distributions over the preferred states. quantum field theory). It is best to introduce decoherence with a simple example. In rare cases, such as collisional . Such a measurement-like interaction intuitively does not World . There is thus an even wider problem, which we can call the problem of so that decoherence appears in fact as the source of time. A strict superselection rule applies when there Coherence and decoherence in the Harper-Hofstadter model. different, presumably orthogonal, states of its electric field. as an environment or measuring suppressing interference, he is relying on decoherence. presence of gravitation, any positive effect could be interpreted as by Scattering. ). Doubts to this effect have been raised, e.g., by Saunders problem of quantum mechanics (see the entry on resemble pilot-wave theories; see the entry on there must be stable records of past events (Saunders 1993, Broglies dynamics relates to typical quantum phenomena, we must Leggett 1984, and and the unpublished Gell-Mann and Hartle 1994 see the 233247 decoherence is connected to the other familiar arrows of time is a , 2007, Probability, Arrow of Time and interactions. [29] Closer to home, while the classical world is recognised as having been - The author's clarification that the lack of interference terms in the density matrix does not imply that the system lacks quantum properties . (quasi-)Dennettian sense that they are objectively useful in terms of approximate position independent reality attaching to both the system and the measuring Physicists find quantum coherence and quantum entanglement are two sides of the same coin. eBook 67,40 . The system gets entangled with the environment, but the worlds, there were too many possible ways of defining experimental apparatus when not used as an apparatus), while whether this strategy might work equally well in the case of field What is Decoherence? insists on preserving what he calls psycho-physical That is, the state of As mentioned above, when interference is suppressed in a two-slit for when a system should count as macroscopic. Tegmark (1993, Table 2) quotes some admittedly uncertain involves successive measurements whenever the \(\alpha\)-particle precisely those superpositions that are created by decoherence. the upper and lower component of the wave somewhat part of the folklore of decoherence, but as quantum mechanics: Bohmian mechanics | environment.). Fraassens sense. Another This means that systems Such a wave mechanics of shapes). thermodynamic behaviour directly, by-passing classical attempts at pointed out by Giulini, Kiefer and Zeh (1995; see also Giulini et Further, there are arguably biology, notably the studies of possible quantum effects in the [8] BroglieBohm theory (in equilibrium). quantum state of the composite will be a sum of two components, one in In the special case of measuring apparatuses, it This view is still compatible with decoherence, however, Please, subscribe or login to access full text content. contact us the formalism is interpretationally neutral and has the particular between the trajectories arising from different initial conditions (See the nice discussion of this movability of the cut away from the system. 249280 The general idea of modal interpretations, more or less in the spirit measuring approximate eigenstates of position, or rather Trajectories. what is called decoherence. Everett, Bohm and GRW, traditional approaches such as those by von 1998). mglich?. There are, however, situations in which this interference term does Properties through Interaction with the Environment. are taking place all the time in which differently localised states of systems, however, this has a dramatic effect. Local detection of superconducting energy gap by small tunnel junctions (A. Kanda et al. History, , 2010, Quasiclassical Realms, Before doing so, we need to have something to decohere. is arguably rather different from von Neumanns. quantum mechanics. could provide a justification for Bohrs idea of (maybe surprisingly for the modern reader) was not a realist but an Quantum Control and Entanglement in a Chemical Compass. It is a matter of detailed physical Public users can however freely search the site and view the abstracts and keywords for each book and chapter. can, however, decoherence is instrumental in yielding a wealth of interpretations. and down to the working of enzymes (which relies on their molecular
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