|  Wave-Function Collapse in Quantum Mechanics | 
In General > s.a. classical limit of quantum theory.
  * Idea: When a
    quantum measurement is performed, and a certain eigenvalue of the
    corresponding operator observed, the wave function "suddenly" turns
    into a corresponding eigenvector; a.k.a. quantum-state reduction;
    Wigner suggested that conscious observation causes collapse.
  * "Reality": Is this a
    physical process, or is it just related to our knowledge and description
    of the system? The results on non-local correlations in moving frames
    make it more difficult to consider the projection postulate as a
    compact description of real collapses of the wave function.
  > Related topics: see collapse
    as a dynamical process [including state recovery]; decoherence;
    locality and localization; measurement;
    quantum experiments.
  > Online resources:
    see SEP page.
And Relativity, Covariant Form > s.a. causality violations.
  * Status: Some relativistic
    models entail excitation of nuclear states which exceeds that of experiment.
  * And causality: Despite some
    claims, it is well known that the process of wave packet reduction cannot
    be used for superluminal communication.
  * Hellwig-Kraus reduction: The
    wave function is collapsed along the boundary of the past of the measurement.
  @ General references: Aharonov & Albert PRD(81) [non-local measurements without violating causality];
    Mielnik FP(90) [collapse cannot be consistently introduced];
    Pearle in(90),
    in(92);
    Finkelstein PLA(00) [projection];
    Ghirardi qp/00;
    Srikanth qp/01,
    Gambini & Porto PLA(02)qp/01,
    NJP(03) [covariant];
    Zbinden et al PRA(01) [non-local correlations in moving frames];
    Myrvold SHPMP(02) [compatible];
    Socolovsky NCB(03);
    Byun FP(04);
    Jadczyk AIP(06)qp;
    Blood a1004 [relativistic consistency];
    Wen a1008 [and path integrals];
    da Silva et al IJMPB(13)-a1012 [observer independence];
    Lin AP(12)-a1104 [atom + quantum field model];
    Bedingham et al JSP(14)-a1111;
    Ohanian a1703 [past-light cone collapse];
    Myrvold PRA(17)-a1709 [need for non-standard degrees of freedom].
  @ For quantum field theory:
    Bedingham JPA(07),
    FP(11) [stochastic model].
  @ Relativistic GRW mechanism: Tumulka JSP(06)qp/04,
    AIP(06)qp,
    FP(07)qp/06;
    Conway & Kochen FP(06) [not possible],
    FP(07)qp [reply to comments].
Models
  * Spontaneous collapse models:
    They add a non-linear noise term to the Schrödinger equation and extract
    definite measurement outcomes either from the wave function (mass density ontology)
    or the noise itself (flash ontology); They can be Markovian or non-Markovian.
  @ Models: Bussey PLA(93) [phonon model];
    Assing & Hilbert a1405 [damped, driven];
    Ho et al NJP(16)-a1504 [classically driven mechanical oscillator].
  @ Spontaneous collapse models:
    Berg hp/96 [phenomenological];
    Diósi a1710-ch [intro];
    Tilloy & Wiseman a2105 [recast as Bohmian theories].
  @ Stochastic: Diósi JPA(88);
    Jibu et al PLA(90);
    Brody & Hughston JMP(02) [as simulation],
    JPA(06)qp/05 [quantum noise],
      JMP(05) [finite-time];
    Brusheim-Johansson & Hansson qp/06 [chaotic].
  @ Lattice, numerical: Dowker & Henson JSP(04)qp/02;
    Dowker & Herbauts CQG(04)qp,
    FPL(05)qp/04 [causal, 1+1 null lattice];
    Bassi & Ippoliti PRA(04)qp/03 [2-level system];
    Gao PRS(13)-a1304 [discrete energy-conserving model].
  @ Tests of collapse models: Bahrami et al PRL(14) [non-interferometric];
    Adler & Vinante PRA(18)-a1801 [bulk heating effects];
    Chelvaniththilan a2010.
References
  > s.a. axioms [projection postulate]; many-worlds
  interpretation; quantum information (transfer).
  @ I: news pw(07)aug [for light, step-by-step].
  @ General: Bussey PLA(84);
    Home & Whitaker PLA(86),
    comment Hnizdo PLA(87);
    Pearle in(86);
    Damnjanović PLA(88) [as phase transition];
    Home & Whitaker PLA(88);
    Krips BJPS(88);
    Van Kampen PhyA(88);
    Ballentine FP(90) [projection postulate],
    PRA(91) [criticism of some thories];
    Gottfried in(90);
    Namiki et al PLA(94);
    Fioroni & Immirzi gq/94;
    Kadomtsev & Kadomtsev SPU(96) [rev];
    Ozawa AP(97)qp,
    qp/97-conf,
    FdP(98)qp/97 [operational];
    Nakhmanson qp/02 [local-realistic];
    Zurek PRA(07)qp/07 [information transfer and origin of quantum jumps];
    Socolovsky a0806 [geometrical point of view];
    Omnès a0911 [derivation of reduction],
    FP(11)-a1105 [and decoherence];
    Hegerfeldt & Sala Mayato PRA(12)-a1111 [Lüders vs von Neumann reduction];
    't Hooft a1112;
    Hájíček a1311;
    Singh CS-a1810 [non-technical rev].
  @ Not needed, not physical: Fox AJP(83)jan [joint probability operators];
    Keller AJP(90)aug [and probabilities];
    Zeh PLA(93);
    Griffiths PRA(02) [resolving paradoxes];
    Schlosshauer AP(06)qp/05 [evidence];
    Blood a0808 [difficulties of collapse view];
    Wechsler a1002 [the other branches don't disappear];
    Stoica QSMF(17)-a1607;
    > s.a. interpretations [statistical].
  @ Unitarity: Zurek PRA(13)-a1212 [and repeatability of measurements];
    Moldoveanu a1305 [unitary realization].
  @ And consciousness: Thaheld BioSys(05)qp;
    Acacio de Barros & Oas a1609;
    Okon & Sebastián Syn-a1801 [consciousness-based model];
    Kent a2009;
    Chalmers & McQueen a2105-in [with theory of consciousness and quantum collapse dynamics].
  @ Conceptual: Landsberg & Home AJP(87)mar [and the statistical interpretation];
    Svetlichny a1104 [and the subjective world];
    Cowan & Tumulka BJPS(16)-a1307 [epistemology];
    Srikanth a2008 [operational reality, signaling and locality];
    Castellani a2011
      [as collapse of histories rather than collapse of states];
    Wechsler JQIS-a2102 [critical discussion of interpretations];
    > s.a. Individuality.
  @ And measurement: Gambini qp/98;
    Gangat PRA(13)-a1303 [observing controlled quantum state collapse];
    Bera & Bera a1910 [quantum measurement without collapse];
    > s.a. types of measurement [continuous].
  @ Related topics: Clarke IJTP(73) [quantum theory with smooth collapse];
    Scully et al PRP(78) [Stern-Gerlach example];
    Pearle FP(82) [and the gambler problem];
    Cini & Lévy-Leblond ed-90 [no reduction];
    Gisin PLA(91) [entangled states and non-locality];
    Diósi cm/94 [permanent];
    Suarez PLA(98)qp [simultaneity];
    Isham IJTP(06)qp/05,
    IJTP(06) [topos perspective];
    Yun a1310 [collapse without external observer];
    Samarin a1507 [non-mechanical nature of collapse];
> s.a. observers [without observers].
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