|  Probability in Quantum Physics | 
In General > s.a. foundations; interpretations;
  hidden variables; many-worlds interpretation;
  pilot-wave theory; quantum mechanics.
  * Role: Probabilities are
    an essential part of the interpretation, obtained from inner products (0
    ≤ cos2θ ≤ 1).
  * Idea: Probabilities
    do not behave like in classical physics; The basic objects for
    questions Q are probability amplitudes A(Q),
    from which the probabilities are calculated as P(Q)
    = |A(Q)|2;
    Quantum probability is a variant of contextual probability.
  * Calculation: In general,
    when an event can occur in several different ways, its probability amplitude
    is the sum of those for the individual ways (interference),
A(Q) = ∑i A(Q, i) ;
However, if an experiment is capable of determining which alternative is followed, then interference is lost; For example, if Q is a question whose answer depends on what the system does up to a time t, then
P(Q) = ∑x |A(x at tf, a)|2 = |A(Q)|2 , where tf > t .
  * Remark: Independence on
    t in the above calculation is equivalent to unitarity; One point of view
    is that probability doesn't change in time; We often ignore the fact that when we
    talk about time dependence we're talking about different experiments.
  * QBism:
    Quantum Bayesianism or the quantum-Bayesian approach to quantum theory, the personalist
    Bayesian view of probability in quantum theory; This view is widely held in general
    but not by many physicists; Some physicists who have argued for it are Caves, Fuchs,
    Schack, and Mermin (Don Page thinks that there are both frequentist and personalist
    probabilities); It has profound implications for the meaning of quantum mechanics.
  > Related topics: see
    Probability Current; Wigner's Friend.
References
  > s.a. measurement in quantum theory; probabilities
  in physics [negative probabilities, general probabilistic theories]; QBism.
  @ Intros, reviews: 
    Cufaro Petroni FP(92);
    Meyer 95;
    Sudarshan qp/01;
    Rédei & Summers SHPMP(07)qp/06 [and von Neumann algebras];
    Sontz a0902 [simple introduction];
    Janotta & Hinrichsen JPA(14)-a1402;
    Khrennikov 16 [and classical];
    Svozil a1707 [and correlations];
    Schleißinger a2001 [simple].
  @ General references: Accardi PRP(81);
    Accardi & von Waldenfels ed-85;
    Van den Berg et al PhSc(90)mar;
    Halpin PhSc(91)mar;
    Youssef MPLA(91);
    Farina AJP(93)may;
    Gudder IJTP(93);
    Ismael BJPS(96) [conceptual];
    Velleman AJP(98)nov;
    Noyes & Etter PE(99)qp/98;
    Adler qp/00-proc [postulated vs emergent];
    Barnum et al PRS(00)qp/99;
    Khrennikov qp/01 [context-dependent];
    Rylov qp/01 [dynamically based];
    Belavkin IDAQP(00)m.PR/05 [history];
    Dreyer qp/06 [emergent probabilities];
    Lehrer & Shmaya PRS(06) [qualitative approach];
    Tipler qp/06;
    de la Torre EJP(08);
    Rave a0806 [interpretation with closed loops and phases];
    Page PLB(09) [insufficiency of quantum state];
    Bub a1005-in [and information theory];
    Janssens PhD(10)-a1011;
    Leifer & Spekkens PRA(13)-a1107 [quantum theory as a causally neutral theory of Bayesian inference];
    Blackman & Hsiang PE-a1110 [from large number of degrees of freedom];
    Pfister MS-a1203;
    Aerts & Sassoli de Bianchi a1401,
    a1401;
    Hiley LNCS(14)-a1408-conf [structure processes, and non-commutative probability theory];
    Yukalov & Sornette PTRS-a1601 [general definition];
    Porta Mana a2007 [conditional probabilities];
    Niestegge Ent(20)-a2009 [algebraic origin].
  @ And quantum foundations: Khrennikov qp/01-conf;
    Wilce FP(10);
    Holik et al AP(14)-a1211 [origin];
    Fröhlich & Schubnel a1310;
    de Ronde in-a1506 [probabilities as objective knowledge];
    Garola a1806 [epistemic interpretation];
    de Ronde et al a1903 [interpretation];
    > s.a. origin of quantum theory.
  @ From classical probability: Slavnov TMP(06)qp/07;
    Grigorescu PhyA(08)-a0711 [classical Fokker-Planck equation and quantum Brownian motion];
    Groessing et al a1403.
  @ And classical probabilities:
    Khrennikov & Loubenets FP(04)qp/02;
    Khrennikov JMP(02),
    AIP(05)qp/03;
    Nyman IJTP(10)-a0906 ["quantum-like representation algorithm"];
    Farenick et al JMP(11)-a1110 [classical and non-classical randomness, in terms of operator-valued measures];
    Hardy a1303-ch;
    Dzhafarov & Kujala FP(14)-a1305,
    a1312-PLoS;
    Khrennikov a1406-conf;
    Hofmann a1606-proc;
    Garner & Müller a2004.
  @ And decoherence: Bacciagaluppi SHPMP(07)qp [time-directed probability];
    Jordan & Chisolm PLA(09)-a0801.
  @ Objective vs subjective probabilities: Mohrhoff AJP(01)aug-qp/00;
    Saunders ch(05)qp/04;
    Srednicki PRA(05)qp;
    Huber BJPS(05) [as basis for scientific reasoning];
    Ballentine AIP(07)-a0710;
    Maudlin SHPMP(07);
    Szabó SHPMP(07);
    Glynn BJPS(10)#1 [deterministic chances];
    > s.a. ψ-Epistemic Theories;
      ψ-Ontic Theories.
  @ Non-Kolmogorov: Szabó IJTP(94),
    IJTP(95)gq/94,
    FPL(95)gq/94,
    qp/96;
    Khrennikov JMP(00)qp,
    a0709 [and Bell inequalities].
  @ Bayesian approach: Caves et al PRA(02)qp/01;
    Pitowsky SHPMP(03)qp/02;
    Schack qp/02 [and Hardy's axioms for quantum mechanics];
    Appleby FP(05)qp/04,
    O&S(05)qp/04;
    Marlow AP(06)qp/05 [histories],
    gq/06,
    JMP(06)qp;
    Caves et al SHPMP(07)qp/06 [concept of certainty];
    Bub SHPMP(07);
    Rau AP(09)-a0710 [quantum vs classical];
    Fuchs & Schack RMP(13).
  @ Quasi-probability representation: Ferrie RPP(11)-a1001;
    Ferrie et al PRA(10) [necessity of negative probabilities];
    Ryu et al PRA(13)-a1206 [operationally defined, for qudits].
  @ Related topics: Page qp/95,
    IJMPD(96)gq/95 ["sensible quantum mechanics", without probabilities];
    Shirokov qp/06 [on set of states];
    Kupczynski a0810-conf [statistical predictions];
    Döring & Isham JMP(12)-a1102 [as truth values in suitable sheaf topoi];
    Loeliger & Vontobel a1201-conf [factor-graph representation];
    Stairs SHPMP(11);
    Henson a1210 [Consistent Exclusivity];
    Sokolovski PRD(13)-a1301 [for classes of Feynman paths in spacetime];
    Nenashev PS(14)-a1406 [from Zurek's envariance and  Gleason's theorem];
    > s.a. bell inequalities; Born Rule;
      experiments on quantum mechanics; Gleason's Theorem;
      histories formulations [including extended probabilities];
      measure theory; mixed states;
      quantum collapse [GRW]; representations [tomographic].
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