|  Path-Integral Approach to Quantum Theory | 
In General > s.a. formulations of quantum theory.
  * History: Introduced in quantum mechanics by
    Feynman, they have since pervaded all areas of physics where fluctuation effects are important.
  * Idea: One converts a problem formulated in
    terms of operators into one of sampling classical paths with a given weight; One gives a set
    of histories, the amplitude for each history, a rule for summing over histories (measure), and
    a complete and exclusive set of observables; Then we can find (relative) probabilities; For
    example, the transition amplitude that a system with an action S, in state \(|a\rangle\)
    at time t, will be in state |b\(\rangle\) at time t' is given by
\(\langle\)b, t' | a, t\(\rangle\) = ∫tt' \(\cal D\)(all interpolating q) exp{iS[q]/\(\hbar\)},
    summing over all paths q(t) that move forward in time;
    Shows that quantum mechanics is a generalization of classical stochastic
    theory in which the probability measure is replaced by a quantum measure.
  @ General references: Feynman PhD(42);
    DeWitt-Morette et al PRP(79);
    Marinov PRP(80);
    Khandekar & Lawande PRP(86);
    Cartier & DeWitt-Morette JMP(00);
    Ingold LNP(02)qp [and dissipative systems];
    Dowker et al JPA(10)-a1002 [and Hilbert space];
    Zinn-Justin TMP(11) [rev];
    Moshayedi a1902-ln.
  @ History: Derbes AJP(96)jul;
    Antoci & Liebscher AFLB(96)phy/97 [Wentzel as forerunner];
    Inomata & Junker in(99)qp/98;
    Klauder qp/03;
    Albeverio & Mazzucchi JSP(04) [status];
    Parrochia a1907;
    Hari Dass a2003 [Feynman and Dirac path integrals];
    Robson et al a2105 [+ optics and photonics];
    {> s.a. #Wentzel}.
  @ Introductions / Texts: Brown ed-05;
    Feynman & Hibbs 65;
    Fried 72;
    in Felsager 81;
    Schulman 81;
    Scadron 91;
    Khandekar et al 93;
    Grosche ht/93-ln;
    DeWitt-Morette ed-JMP(95)#5;
    Grosche & Steiner 98 [handbook];
    MacKenzie qp/00-ln;
    't Hooft ht/02-conf;
    Zinn-Justin 04; Simon 05;
    Feynman & Brown ed-05 [PhD dissertation etc,
      r CQG(07)];
    Cartier & DeWitt-Morette 07;
    Klauder 11;
    Rosenfelder a1209-ln;
    Fahssi a1303-ln;
    Nguyen JMP(16)-a1505
    + YouTube [mathematical];
    Gozzi et al 16.
  @ Texts, heuristic: Ramond 81;
    Rivers 87;
    Kleinert 09 [with other applications];
    Das 19.
  @ Texts, constructive: Glimm & Jaffe 87;
    Rivasseau 91.
  @ Texts, III: Swanson 92;
    Roepstorff 94;
    Chaichian & Demichev 01;
    Mazzucchi 09;
    Dittrich & Reuter 20.
The Measure
  > s.a. integration theory [functional integrals].
  * Choice: When the
    space of histories is a linear space, use a Gaussian measure.
  @ Mathematical: Albeverio & Hoegh-Krohn 76;
    Cameron & Storvik 83;
    Yamasaki 85;
    Klauder in(86);
    Botelho a0902.
  @ Types of paths used:
    Bogojevic & Belic PLA(05) [jaggedness of paths];
    Koch & Reyes IJGMP(15)-a1404 [with time-scale parameter, using differentiable paths].
  @ Related topics: Swanson PRA(94) [and canonical transformations];
    Dynin LMP(98)m.FA [time slicing construction].
Other Formulations 
  > s.a. Polymer Representation;
  Schwinger's Action Principle.
  * Closed-time version:
    The generating function is
Z[J+, J−]:= J−\(\langle\) 0−|0+ \(\rangle\)J+ = ∫ \(\cal D\)φ+ \(\cal D\)φ− exp{i (S[φ+] + J+[φ+] − S*[φ−] − J−[φ−])} .
  @ General references:
    Hegseth qp/04 [in momentum space];
    Stannett a0805-conf [computable formulation];
    Stoyanovsky a0808 [Green-function-like distributions];
    Rubin TMP(08) [calculation method, differential equation];
    Kochan APoly-a0812 [using only classical equations of motion],
    IJMPA(09),
    JGP(10),
    PRA(10)-a1001 [non-Lagrangian systems];
    Ootsuka & Tanaka PLA(10)-a0904 [Lagrangian, in terms of Finsler geometry];
    Nagao & Nielsen PTP(13)-a1205 [complex action theory, with future included];
    Mou et al a1902 [real time, complex field variables];
    Buchholz & Fredenhagen a1905 [and dynamical algebras].
  @ In phase space: Mizrahi JMP(75) [and Weyl transforms];
    Takatsuka PRL(88);
    Sonego PRA(90) [Wigner functions, etc];
    Marinov PLA(91);
    Farhi & Gutmann AP(92);
    Niemi & Tirkkonen AP(94)ht/93;
    Whelan gq/97-proc [skeletonization];
    Klauder qp/97;
    Shabanov & Klauder PLB(98)qp [symplectic manifolds];
    Ferraro & Leston IJMPA(01)gq/00 [in curved spacetime];
    Albeverio et al JMP(02);
    Ichinose CMP(06) [mathematical theory];
    Yamashita JMP(11)
      [in terms of Brownian motions and stochastic integrals].
  @ World-line formalism:
    Schmidt & Schubert ht/98-conf;
    Bastianelli & Zirotti NPB(02);
    Schubert AIP(07)ht [for QED].
  @ Closed-time version:
    Schwinger JMP(61);
    Keldysh ZETF(64);
    Korenman AP(66);
    Chou et al PRP(85);
    Manoukian NCB(87), NCA(88);
    Jordan PRD(86) [in curved spacetime];
    Calzetta & Hu PRD(87) [in cosmology];
    Cooper ht/95.
Concepts and Techniques
  > s.a. coherent states; lattice
  field theory; partial differential equations.
  * Regularization: It can be done by
    using a lattice (the most common), or Klauder's continuous time regularization.
  @ Hamiltonian and Lagrangian: Grosse-Knetter PRD(94)hp/93,
    PhD(93)hp;
    Łopuszański mp/00 [classically equivalent Lagrangians].
  @ Change of variables:
    Smolyanov & Smolyanova TMP(94);
    Kleinert & Chervyakov PLA(00)qp;
    Johnson-Freyd a1003
      [for fields taking values on a general fiber bundle];
    Cugliandolo et al a1806 [with one degree of freedom].
  @ Non-standard analysis:
    Nakamura JMP(91);
    Loo JMP(99)mp/00,
    JPA(00)mp [general],
    JMP(99)mp/00 [sho].
  @ Approximation methods: Blau et al PLB(90) [geometrical, WKB];
    Kleinert PLB(92);
    Wasilkowski & Wozniakowski JMP(96);
    Horváthy CEJP(11)qp/07 [semiclassical, Maslov correction];
    Paulin et al JSP(07) [low-temperature behavior];
    Smirnov JPA(08) [limiting procedures];
    Thrapsaniotis JPA(08) [based on central limit theorem].
  @ Diagrammatic expansions: Halliwell PLA(95)qp [path decomposition expansion];
    Johnson-Freyd LMP(10)-a1003,
    JMP(10)-a1004.
  @ Numerical: Wandzura PRL(86) [Monte Carlo];
    Gerry & Kiefer AJP(88)nov;
    Onofri & Tecchiolli PS(88);
    Samson JPA(00)qp [time discretization];
    Sauer phy/01-in [rev];
    Bogojevic et al PRL(05) [acceleration];
    Moch & Schneider PoS-a0709 [using difference equations];
    Grimsmo et al PLB(13) [consequences of modified discrete-time lattice actions];
    Alexandru et al a2007
      [Monte Carlo method, approaches to the sign problem].
  @ And boundary conditions: Jaroszewicz PRL(88);
    Asorey et al qp/06-proc [cannot describe highly non-local ones].
  @ Related topics: Henderson & Rajeev JMP(97)ht/96 [and renormalization];
    Jizba & Kleinert PRD(10)-a1007
      [superstatistics approach];
    Sekihara a1201 [Metropolis algorithm];
    Halliwell & Yearsley PRD(12)-a1205,
    JPCS(13)-a1301 [amplitudes for spacetime regions and the quantum Zeno effect];
    Sokolovski PRD(13)-a1301 [probabilities for classes of paths in spacetime];
    LaChapelle a1505 [functional integral representations of C*-algebras];
    Jizba & Zatloukal PRE(15)-a1506 [local-time representation];
    Cahill a1501
      [without using the Hamiltonian, for theories that are not quadratic in time derivatives];
    Amaral & Bojowald AP(18)-a1601 [and the problem of time];
    Malgieri et al AJP(16)sep [using energy-dependent propagators];
    Kochetov a1811 [continuous-time formulation];
    Morales-Ruiz a1910 [differential Galois approach];
    Trapasso a2004 [time-frequency analysis].
  > Related topics:
    see Peierls Brackets; Stationary-Phase Approximation;
    Steepest-Descent Approximation; Trace Formulas.
Related Topics
  > s.a. canonical quantum mechanics [canonical transformations, factor ordering];
  quantum systems; regge calculus;
  spacetime foam.
  @ And configuration-space topology: Laidlaw & Morette DeWitt PRD(71);
    Tanimura & Tsutsui AP(97) [on G/H];
    Mouchet a2010;
    > s.a. topology in physics.
  @ And stochastic mechanics:
    Wang PLA(89);
    Boos JMP(07).
  @ Particle vs field: van Holten NPB(95)ht;
    Fujita a0801 [critical review].
  @ In non-commutative spaces:
    Smailagic & Spallucci JPA(03) [non-commutative plane];
    Mignemi & Štrajn PLA(16)-a1509 [1D and 2D Snyder space].
  @ Other generalizations: Kauffmann ht/95 [arbitrary canonical transformations];
    Djordjević & Dragovich mp/00-proc,
    MPLA(97)mp/00 [p-adic];
    Acatrinei JPA(07) [higher-order Lagrangians];
    Lloyd & Dreyer a1302
      [universal path integral, as sum over all computable structures];
    Savvidy MPLB(15)-a1501 [integral over random surfaces, gonihedric action];
    > s.a. generalized uncertainty principle.
  @ Other topics: Menskii TMP(83) [and group theory],
    TMP(92) [and continuous measurement];
    Popov 88 [and collective excitations];
    Sorkin in(90) [and causality];
    Brun gq/94 [and decoherence];
    Marchewka & Schuss PRA(00)qp/99 [and currents];
    Shankaranarayanan & Padmanabhan IJMPD(01) [duality, and electromagnetism];
    Dreisigmeyer & Young mp/01 [as semigroups];
    Ashmead qp/03 [and fluctuations in time?];
    Ord et al qp/04,
    FPL(06) [phase, physical basis];
    Putrov TMP(08)ht/06 [energy representation];
    Furuya JMP(06) [Riemann-type integral];
    Jackiw in(08)-a0711 [and charge fractionalization];
    Witten a1009 [and branes in a two-dimensional A-model];
    Green et al a1607 [and entangled states];
    Gozzi PLA(18)-a1702 [quantum identities for the action];
    Terekhovich a1909-in [ontology];
    > s.a. pilot-wave interpretation; quantum measurements
      [stochastic path integral formalism]; representations [tomography].
Systems > see particle statistics; quantum field theories; quantum gauge theories; quantum gravity; other theories [including spectrum estimation].
 main page
  – abbreviations
  – journals – comments
  – other sites – acknowledgements
  send feedback and suggestions to bombelli at olemiss.edu – modified 4 may 2021