Decoherence of Quantum States  

In General > s.a. Coherence; history of quantum theory; interpretations of quantum mechanics; models of decoherence; quantum chaos.
* Idea: The decay of correlations in the evolution of a system; In quantum theory, the evolution of a pure state into an effectively mixed one due to system-bath interaction; An important concept in the emergence of classical behavior from quantum states for macroscopic systems; Decoherence destroys quantum correlations and interference in Wigner distributions and washes out fine structure in classical distributions, bringing the two distributions and the expectation values closer together.
* Rem: Decoherence does not solve the measurement problem, because it does not solve the so-called "problem of outcomes".
* Decoherence function: The function d(α, β) measures the quantum interference between history propositions α and β.
* Decoherence time scale: τd is the time over which quantum coherence of the system is lost.

Related Topics > s.a. arrow of time; experiments in quantum mechanics; probability; quantum effects [quantum jumps]; vacuum.
* Origin of decoherence: It is often attributed to the system-environment entanglement, but this is not the only source of decoherence; There can also be an intrinsic or fundamental decoherence, and one due to the interaction with the measuring apparatus.
* And classicality: Although decoherence is an important concept in the foundations of quantum theory, it does not by itself solve the measurement problem or the issue of the emergence of classicality; Weinstein suggests that decoherence is best regarded as explaining the persistence of true classicality, rather than the emergence of quasiclassicality.
* Quantum darwinism: A "quantum form of natural selection", an information-theoretic framework for the emergence of the objective, classical world from the quantum substrate, based on the redundant recording of information about a decohering system by its environment, where observers can then intercept it.
@ Decoherence-free subspace: Mundarain & Orszag PRA(07)qp/06 [two-level system in squeezed bath]; Brooke et al PRA(08)-a0806 [N qubits]; > s.a. stochastic processes [Markov].
@ Quantum darwinism: Blume-Kohout & Zurek PRL(08)-a0704 [in brownian motion]; Zwolak et al PRL(09) + news arst(09)sep; Zwolak et al PRA(10)-a0911 [non-ideal environments]; Burke et al PRL(10) [evidence]; Fields IJTP(10)-a1003, Ax(14)-a1102; Brandão et al nComm(15)-a1310; Poostindouz et al a1311-conf; Zurek PT(14)oct-a1412 [rev]; Kastner a1603-in [criticism]; > s.a. consistent histories approach.
@ And pilot-wave interpretation: Sanz & Borondo EPJD(07)qp/03 [decoherence does not imply classical limit].
@ And measurement: Namiki et al 98; Schlosshauer RMP(04); d'Espagnat FP(05) [and Wigner's friend]; Ghose ASL-a1103; Wallace a1111-PTRS [role in measurement]; Mack et al PRP(14) [generalized measurement and the quantum Zeno paradox]; Hobson PT(15)dec; > s.a. types of measurements.
@ Self-induced: Castagnino & Lombardi IJTP(03)qp/02 [in cosmology], SHPMP(04) [general]; Schlosshauer PRA(05)qp [spin bath model]; Castagnino & Lombardi PRA(05)qp [time], PhSc(05)dec [and classical limit]; Castagnino qp/05 [non-integrable systems].
@ And classicality: Weinstein a0807 [emergence of classicality is not generic]; Romanelli PRA(09)-a0905 [without classicality, resonant quantum kicked rotor]; Kofler et al a0906 [no continuous spatiotemporal description]; Weinstein a0906 [decoherence as persistence of classicality]; Mazzola et al PRL(10)-a1001 [quantum vs classical decoherence]; Schlosshauer & Camilleri AIP(11)-a1009 [Bohr's classical concepts]; Okon & Sudarsky FP(16)-a1512.
@ And Lorentz invariance: Milburn PRA(91), gq/03, NJP(06); Bertlmann LNP(06)qp/04 [particle physics]; Cai et al PRA(07) [suppressed dephasing].
@ Time scale, rate of decoherence: Terra Cunha et al qp/04; Dalton JMO(05)qp/04 [macroscopic systems]; Roa et al PLA(07) [stability]; Rodríguez-Rosario et al PRL(11)-a1004 [bound]; Vattay et al PLOS(14)-a1202 [the edge of quantum chaos, coherence and quantum biology]; Bužek et al PRA(12) [direct estimation]; Wang et al PRA(16)-a1601 [degradation under relativistic motion]; > s.a. wave-function collapse.
@ Thermodynamic limit: Lugiewicz & Olkiewicz JPA(02) [spin system]; Frasca PLA(03)qp/02; Frasca in(05)cm/04 [fully polarized states].
@ With energy conservation: Unruh & Wald PRD(95)ht [and causality]; Alicki OSID(04)-a0801 [pure decoherence without dissipation]; Unruh PTRS(12)-a1205.
@ Other topics: Schulman PRA(98)qp/97 [interaction with walls, and error]; Halliwell PRD(99)qp [fate of information]; Omnès qp/01 [as irreversible process]; Camacho IJMPD(01)gq [equivalence principle violations]; Frasca PLA(01), PLA(03) [in thermodynamic limit]; Mohrhoff qp/01 [meaning]; Berman et al PRA(04)qp [survival of quantum properties]; Schützhold & Tiersch JOB(05)qp/04 [and Casimir effect]; Alicki ChemP(06)qp/05-in [decoherence control]; Halliwell PRA(05) [commuting X and P, emergent classicality]; Castagnino et al MPLA(10)-a0907 [effect of random coupling coefficients]; Milburn PTRS(12)-a1201 [and classical control of quantum systems]; Tiersch & Briegel PTRS(12)-a1204 [constructive role in driving quantum dynamics]; > s.a. quantum phase transitions.

References > s.a. entanglement; histories-based quantum mechanics; quantum-to-classical transition.
@ Reviews: Zurek PT(91)qp/03, & Paz NCB(95); Zeh qp/95-in; Giulini et al 96; Zurek PTRS(98)qp; Anastopoulos IJTP(02)qp/00; Zurek RMP(03)qp/01; Joos et al 03; O'Connell IEEE(05)qp-proc; Halliwell CP(05)qp; Zeh in(06)qp/05; Schlosshauer 07.
@ Pedagogical: Haroche PT(98)jul; Bhattacharya et al LAS(02)qp/04; Finkelstein qp/05 [energy decoherence]; Hornberger LNP(08)qp/06-ln; Gamble & Lindner AJP(09)mar; in Chang & Ge 17.
@ Environmentally induced: Joos & Zeh ZPB(85); Joos in(86); Joos qp/99-proc; Kastner SHPMP-a1406 [einselection's 'Loschmidt's Paradox'].
@ Types / sources of decoherence: Anastopoulos & Hu CQG(08)-a0803 [intrinsic/fundamental]; Çetinbas JPA(09) [coherent quantum fluctuations]; Stamp PTRS(12)-a1205 [environmental vs intrinsic]; Wang & Hobill a1412 [environmental vs apparatus]; > s.a. models and systems [gravitational decoherence].
@ General theory: Omnès PRA(97); Wright CMP(98) [decoherence functionals]; Vecchi qp/00 [assumptions]; Fiete & Heller PRA(03)qp/02 [semiclassical]; Blanchard et al PLA(03) [various effects]; Na & Wyatt PS(03) [hydrodynamic formulation]; Znidaric & Prosen JOB(05)qp [t-dependence]; Castagnino & Laura qp/05, et al qp/06 [formalism for open and closed systems]; Merkli et al PRL(07); Gamble th(08)-a0805; Castagnino et al PhSc(07)dec, CQG(08)-a0907 [general framework]; Gorin et al NJP(08)-a0807 [random-matrix theory]; Castagnino et al MPLA(10)-a1001, a1002 [interpretation]; Koksma et al AP(11)-a1012 [two approaches]; Coles PRA(12)-a1110 [and quantum discord, unified view]; Figari & Teta a1209 [Mott's 1929 paper as a precursor]; Castagnino & Fortin IJTP(13)-a1307 [general theoretical formalism]; Sokolov & Zhirov a1311; Fortin et al BJP(14)-a1402 [closed-system approach].
@ Related topics: Morikawa PRD(90); Finkelstein PRD(93)gq; Twamley PRD(93)gq; Zurek & Paz PRL(94)gq; Gell-Mann & Hartle in(98)gq/95; Anglin et al PRA(97)qp/96; Dugić PS(96); Kiefer & Joos LNP(99)qp/98; Paz & Zurek qp/00-ln; Unruh in(00)-a1110 [false loss of coherence]; Scherer & Soklakov AIP(04)qp [long histories]; Castagnino & Fortin MPLA(11) [decaying modes and general definition of the moving pointer basis]; Riedel PRA(15)-a1504 [from classically undetectable sources].
@ Conceptual: Zeh qp/96, LNP(00)qp/99; Stamp SHPMP(06); Marchildon FP(11)-a1001 [and the Everett interpretation]; Lombardi et al IJMPD(11)-a1009.
@ Phase space picture: Kiefer qp/97-in, Diósi APH-qp/02-in, Ozorio de Almeida JPA(03) [Wigner functions]; Grewal PRA(02) [and coherent states].

Decoherence is like capitalism. Its proponents regard it as obvious, given human nature, and its success seems overwhelming. Competitors largely belong to the past, or get the impression they do. Consequently, although serious analysis finds deep flaws in it, the promise of huge benefits continues to attract new adherents with the naivety of those who enroll in a pyramid scheme. – N P Landsman SHPMP(09).

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