Wave function collapse: Difference between revisions

Revision as of 20:00, 26 December 2024

Revision as of 20:05, 26 December 2024

Line 70:

Quantum decoherence explains why a system interacting with an environment transitions from being a [[Quantum state#Pure states as rays in a complex Hilbert space|pure state]], exhibiting superpositions, to a [[Quantum state#Mixed states|mixed state]], an incoherent combination of classical alternatives.<ref name="Stanford1" /> This transition is fundamentally reversible, as the combined state of system and environment is still pure, but for all practical purposes irreversible in the same sense as in the [[second law of thermodynamics]]: the environment is a very large and complex quantum system, and it is not feasible to reverse their interaction. Decoherence is thus very important for explaining the [[classical limit]] of quantum mechanics, but cannot explain wave function collapse, as all classical alternatives are still present in the mixed state, and wave function collapse selects only one of them.<ref name=Schlosshauer/><ref>{{cite journal |author1=Wojciech H. Zurek |title=Decoherence, einselection, and the quantum origins of the classical |journal=Reviews of Modern Physics |date=2003 |volume=75 |issue=3 |page=715 |doi=10.1103/RevModPhys.75.715 |arxiv=quant-ph/0105127 |bibcode=2003RvMP...75..715Z |s2cid=14759237 }}</ref><ref name="Stanford1" />

CalculationsThe form of decoherence known as [[quantumeinselection|environment-induced decoherencesuperselection]] showproposes that when a quantum system interacts with the environment, the superpositions ''apparently'' reduce to mixtures of classical alternatives. Significantly, theThe combined wave function of the system and environment continue to obey the Schrödinger equation throughout this ''apparent'' collapse.<ref name=Zurek>{{cite journal |last=Zurek |first=Wojciech Hubert |title=Quantum Darwinism |journal=Nature Physics |year=2009 |volume=5 |issue=3 |pages=181–188 |doi=10.1038/nphys1202 |arxiv = 0903.5082 |bibcode = 2009NatPh...5..181Z |s2cid=119205282}}</ref> More importantly, this is not enough to explain ''actual'' wave function collapse, as decoherence does not reduce it to a single eigenstate.<ref name=Schlosshauer>{{cite journal |last=Schlosshauer |first=Maximilian |title=Decoherence, the measurement problem, and interpretations of quantum mechanics |journal=Rev. Mod. Phys. |year=2005 |volume=76 |issue=4 |pages=1267–1305 |doi=10.1103/RevModPhys.76.1267 |arxiv = quant-ph/0312059 |bibcode = 2004RvMP...76.1267S |s2cid=7295619}}</ref><ref name="Stanford1">{{cite encyclopedia

| last = Fine

| first = Arthur