In General > s.a. electromagnetism; history of quantum physics; light; photon phenomenology [propagation and effects]; Wavelets.
* History: Introduced by Planck; Used by Einstein to explain the photoelectric effect; Called "light quantum" by Einstein and then others until Gilbert N Lewis introduced the name "photon" in a 1926 letter to Nature (although it was for a different concept).
* Evidence: Compton effect; Photoelectric effect (although photons are not necessary if one uses the quantum theory of electrons); More direct evidence is the fact that atoms recoil when emitting radiation, and they are required for accurate descriptions of certain processes involving fluctuations in the electromagnetic field.
* Mass bounds: 1975, mphoton < 6 × 10−16 eV/c2, from Jupiter's B field; 1989, mphoton < 6 × 10−16 eV/c2 ≈ 4 × 10−51 kg, from Earth's B; 1994, mphoton < 3 × 10−27 eV/c2 [?]; 1998, mphoton < 7 × 10−17 eV/c2, from the Cavendish balance; Bounds are also obtained from timing of GRB pulses; 2012, mphoton < 4 × 10−20 eV/c2 from black-hole superradiance instability.
@ General references: Kragh a1401 [origin of the name]; Rodrigues a1701 [and the Maxwell equations]; Scully & Sargent PT(72)mar [hist, concept].
@ Mass, observation: Goldhaber & Nieto RMP(71), RMP(10)-a0809; Montanet et PDG PRD(94); Schaefer PRL(99)ap/98 + pn(98)mar [GRBs]; Neyenhuis et al PRL(07) [proposed interferometer experiment sensitive down to 9 × 10−50 g]; Accioly et al PLA(10) [VLBI]; Hojman & Koch a1209; Qian SCPMA(12)-a1406 [using strong gravitational lensing data]; Wu et al ApJL(16)-a1602, Bonetti et al PLB(16)-a1602, PLB(17)-a1701 [constraints from fast radio bursts]; Zhang et al JHEA-a1607 [using GRBs]; Wei et al RAA(17)-a1608 [radio pulsars in LMC and SMC]; Yang & Zhang ApJ(17)-a1701 [from pulsar spindown].
@ Mass, theory: Prokopec et al PRL(02) [generation in inflation]; Accioly & Paszko PRD(04) [bound from light deflection]; Pal PhyTea(05)phy/06 [history]; Sidharth FPL(06); Cafaro et al AHEP(07)ht [and magnetic monopoles]; Spavieri & Gillies G&C(10)-a1005 [electromagnetic momentum and speed of light in moving media]; Fonseca & Vargas-Paredes BJP(10)-a1005; Accioly et al CQG(10), PRD(10)-a1012 [bounds]; Pani et al PRL(12)-a1209 [bound from instabilities around rotating black holes]; Diamantini et al JPA(14) [induced by vortex gauge interactions]; > s.a. emergent gravity; modified electromagnetism; photon phenomenology [effective mass].
@ Other properties: Altschul PRL(07) + pw(07)jul, APP(08)-a0711 [upper bound of 10−32e or less on electric charge, 10−24e·cm on magnetic moment]; Devenish NPPS(08) [structure functions, overview]; Hankins et al AJP(13)jun [experiment on charge upper bound]; Heeck PRL(13) + news pw(13)jul [lifetime bound]; Mielniczuk et al a1702 [anomalous magnetic moment]; > s.a. gravitating matter [gravitational field].
@ Classical description: Barut PLA(90) [model]; Marshall & Santos qp/97; Simon et al qp/97 [photon-number distribution]; > s.a. gas.
> Related particles: see Notoph; Paraphoton; photon phenomenology [dark photon].

Photon States > s.a. maxwell's equations.
@ Wave function: Inagaki PRA(98); Zalesny IJTP(04) [Białynicki-Birula wave function]; Białynicki-Birula qp/05-in [rev]; Raymer & Smith qp/06-conf; Lapaire & Sipe qp/06 [and interference]; Tamburini & Vicino PRA(08)-a0807 [covariant, and QED]; Bradler a0910 [Lorentz-invariant wave packets]; Mohr AP(10); Babaei & Mostafazadeh JMP(17)-a1608 [Hilbert space]; Kiessling & Tahvildar-Zadeh JMP(18)-a1801 [Dirac-type equation]; Wawrzycki APPB(16)-a1810; Białynicki-Birula & Białynicka-Birula a1912.
@ Wigner function: Bertet et al PRL(02) [measurement, single-photon state]; Przanowski et al FdP(21)-a2006.
@ Single photon states: Pfleegor & Mandel PR(67) [from 2 lasers]; Adlard et al PRL(97); Lvovsky et al PRL(01)qp; Grangier & Abram pw(03)feb; Oxborrow & Sinclair CP(05) [sources]; news pn(08)mar [shortest one, 65 fs]; Ipp et al PRL(09) [yoctosecond, GeV-scale pulses]; Stobińska et al AQC-a1002 [interaction with single atom]; Sangouard & Zbinden JMO(12)-a1202 [uses]; Afzenius et al PT(15)dec [using atoms to store the quantum state of a photon]; Kobakhidze a1604 [wave function, in Krein space]; Driessen a1707 [non-locality and non-temporality]; Baskal et al a1711-conf [spin states and helicities]; Hoffmann a1804 [probability amplitudes]; Hoffmann a2005 [no point-localized states].
@ N-photon states: Bertet et al PRL(02) [2-photon]; Brown et al PRA(03)qp/02; Czachor PLA(03)qp/02; Ou PRA(06)qp [temporal distribution]; Hawton qp/06 [1- and 2-photon states]; Gleyzes et al Nat(07)qp/06 [observing quantum jumps]; Wu et al PLA(12) [coherent superposition of localized and delocalized phases]; Ilyin OP(15)-a1406 [photon statistics and bunching effect; generalized binomial distribution]; Leff AJP(15)apr [particle-number fluctuations and compressibility]; > s.a. fock space.
@ Photon-added and subtracted states: Walschaers et al PRA(17)-a1708 [phenomenology]; Malpani et al AdP(19)-a1904 [quantum phase properties].
@ Other states: Wiseman & Vaccaro PRA(02)qp/99, PRA(02)qp/01 [stationary laser states]; Asbóth et al PRL(05)qp/04; Bendjaballah PRA(06); Zavatta et al PRA(08)-a0803 [cavity-enhanced generation]; VanValkenburgh JMP(09) [semiclassical]; Park et al NJP(10) [experimental scheme to verify the photon commutation relations]; Pathak & Banerji PLA(14)-a1307 [non-classicality and decoherence of binomial states]; Coelho et al PRA(15)-a1502 [Gaussian character]; > s.a. QED; Squeezed States.

Other Quantum Aspects > s.a. QED and modified QED; particle statistics; photon phenomenology; quantum optics; types of coherent states.
* de Broglie relation: The relationship between momentum and wavelength or wave vector, p = ħk.
* Twisted light: A technique used to increase the amount of information carried per photon; It involves encoding 2.05 bits per photon by using the orbital angular momentum of light instead of the more commonly used polarization, which only allows one bit per photon.
@ General references: Einstein AdP(05) [Rigden pw(05)apr]; Scully & Sargent PT(72)mar; Clauser PRD(74) [experiment]; Walls Nat(79)aug [evidence]; Strnad AJP(86)jul; news Nat(96)apr, Sci(96)apr; Leonhardt 97; Kolobov RMP(99); Loudon 00; Paris PLA(01) [verification]; Greenberger et al in(07)-a0712 [Planck, photon statistics, etc]; Mayer a1207 [special relativity and E = hf]; Degiorgio AJP(13)oct [correlations]; Honegger & Rieckers 15 [3 vv]; Parisio a1905 [deformed de Broglie relation].
@ Against photons as physical objects: Marshall qp/02, Rashkovskiy QS:MF(16)-a1507 [electromagnetic waves are classical].
@ Detection: Keyes & Kingston PT(72)mar; Silberhorn CP(07); Hawton PRA(13)-a1304 [by inertial and accelerated detectors]; Reiserer et al Sci(13)nov-a1311 [non-destructive]; Lebedev a1401 [and photon localization]; Biswas & van Enk a2007 [full Hamiltonian description].
@ Descriptions: Leonhardt 97 [states]; Dvoeglazov in(97)phy [various], PS(01) [compositeness?]; Kastner EJTP-a1312 [relationship between virtual and real photons]; Li & Zhang a1803 [intrinsic degree of freedom]; > s.a. particle models.
@ Past of photons: Danan et al PRL(13) + Lundeen Phy(13) [past of photons passing through an interferometer]; Sokolovski a1607, comment Vaidman a1703, reply a1704.
@ Anderson localization: Wiersma et al Nat(97)dec + pn(98)jan; Malfliet PLA(00) [continuum version]; Kaiser JMO(09)-a1003.
@ Other localization: Tan et al PRL(91) [non-locality]; Chiao et al SA(93)aug; Hardy PRL(94); Dotson FP(95); Home & Agarwal PLA(95); Brooke & Schroeck JMP(96) [covariant phase space localization operator]; Keller PRP(05); Hawton PS(12)-a1109 [in spacetime]; Ojima & Saigo a1507; > s.a. quantum locality.
@ And information theory: focus Phy(12) [encoding and detecting information in the shape of the wave function]; Rohde et al PRA(13) [information capacity]; news pw(15)mar [twisted light]; > s.a. quantum information.
@ Spin and angular momentum: Tamburini et al a1201 [upper and lower physical limits to the determination of the orbital angular momentum]; Sun a1407, Leader PLB(16)-a1510 [orbital and spin part of the angular momentum operator]; Yang et al a2004 [expressions for operators]; Aghapour et al a2012.
@ Other quantum mechanics: Peres AJP(84)jul, FP(84); Paul RMP(86); Hawton PRA(99), & Baylis PRA(01) [position operator]; Li a1601 [role of transversality condition]; Hawton PRA(19)-a1902 [covariant quantum theory]; Dobrski et al a2104 [position operator].
@ QED, photon propagator: Esposito mp/05-conf; Lowdon PRD(17)-a1702 [non-perturbative structure].
@ Photons with half-integer spin: news pw(16)may; Parthasarathy & Viswanathan a1605 [as q-fermions].
@ Related topics: Ghose et al PLA(01) [Bohmian trajectories]; Ligare & Oliveri AJP(02)jan [visualization]; Hawton PRA(08) [Lorentz-invariant photon number density]; Dubin et al nPhys(10)-a1002 [quantum-to-classical transition]; Pesci a1108 [minimum wavelength]; > s.a. bose-einstein condensation; graviton.

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