Locality and Localization in Quantum Field Theory

In General > s.a. locality; observables; quantum field theory; quantum particles and states.
* Physics in a bounded region: Cannot be discussed in terms of subspaces of the full Hilbert space , because fields there generate when acting on the vacuum (Reeh-Sleider theorem); Can use local algebras of operators.
* Particles: A sharp localization is impossible in local quantum field theory; One often sees the Compton wavelength used as limit for localizability, but its spatial probability density can be much narrower.
* Non-local theories: For example, a non-local version of QED; Observables in quantum gravity have to be non-local; > s.a. types of quantum field theories.

Specific Theories > s.a. light [standstill].
* Non-locality in quantum gravity: It has been suggested by Markopoulou & Smolin that in a transition from an early quantum geometric phase of the universe to a low-temperature phase characterized by an emergent spacetime metric, locality might have been "disordered", with a mismatch between micro-locality and macro-locality.
@ Quantum gravity, non-locality: Ahluwalia PLB(94); Prugovecki FP(96)gq; Giddings PRD(06)ht [and strings], PRD(06)ht [argument from black hole physics]; Markopoulou & Smolin CQG(07)gq [lqg states]; Sorkin in(08)gq/07 [at scales larger than l_P]; Smrz NCB(06); Arzano et al a0806 [and hidden entanglement, unitarity]; Prescod-Weinstein & Smolin a0903 [and effective dark energy]; > s.a. non-commutative geometry; spacetime foam.
@ Quantum gravity, recovering locality: Hardy a0804-in [formalism locality].
@ QED: Valentini in(90); Moussa & Baseia PLA(98) [single particle in cavity QED]; Bialynicki-Birula & Bialynicki-Birula PRA(09)-a0903 [photons and coherent states]; > s.a. photon, QED phenomenology.
@ Other theories: Buchholz & Fredenhagen LNP(82) [gauge theory, and particle states]; Tetradis PLB(00)hp/99 [as dual Josephson junction]; Chernitskii in(02)qp/03 [and unified theory]; Krekora et al PRL(04) [no limitations for electrons]; Zavialov TMP(04) [and deformed Heisenberg algebra]; Balachandran et al PRD(08)-a0708 [twisted quantum field theory].
> Lattice theories: see ising model [with non-local links]; lattice field theory [localization in random lattices].

References
@ General references: Muller & Butterfield PhSc(94)sep; Jaekel & Reynaud PLA(96)qp; Gottschalk LMP(99)mp/04 [in terms of Wightman functions, in momentum space]; Halvorson PhSc(01)mar [Reeh-Schlieder vs Newton-Wigner]; Chernitskii qp/01; Brunetti et al CMP(03) [generally covariant]; Bostelmann JMP(05)mp/04; Wanng JMP(98)qp/05 [non-locality].
@ Localization: John PT(91)may [light]; Schroer ht/98-ln; Schroer a0711 [quantum mechanics, quantum field theory and quantum gravity].
@ Physics in a bounded region: Reeh & Sleider NC(61); in Haag 92; Strohmaier et al JMP(02)mp [in curved spacetime].
@ Related topics: Tommasini ht/01, ht/01 [and correlations].
> Online resources: Wikipedia page on the Reeh-Schlieder theorem.

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