WordNet

of or relating to a quantum or capable of existing in only one of two states (同)quantized
(physics) the smallest discrete quantity of some physical property that a system can possess (according to quantum theory)
a discrete amount of something that is analogous to the quantities in quantum theory
relating to or performed with the fingers; "digital examination"
displaying numbers rather than scale positions; "digital clock"; "digital readout"
of a circuit or device that represents magnitudes in digits; "digital computer"

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量子
指の / 数字の;計数型の / (タイプライターなどの)鍵(けん),キー
quantumの複数形

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/26 11:24:42」(JST)

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In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction. Behind this, one finds the fundamental notion that a physical property may be "quantized," referred to as "the hypothesis of quantization".^[1] This means that the magnitude can take on only certain discrete values.

A photon is a single quantum of light, and is referred to as a "light quantum". The energy of an electron bound to an atom is quantized, which results in the stability of atoms, and hence of matter in general.

As incorporated into the theory of quantum mechanics, this is regarded by physicists as part of the fundamental framework for understanding and describing nature at the smallest length-scales.

Etymology and discovery

The word "quantum" comes from the Latin "quantus", meaning "how much". "Quanta", short for "quanta of electricity" (electrons) was used in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtz for using the word in the area of electricity. However, the word quantum in general was well known before 1900.^[2] It was often used by physicians, such as in the term quantum satis. Both Helmholtz and Julius von Mayer were physicians as well as physicists. Helmholtz used "quantum" with reference to heat in his article^[3] on Mayer's work, and indeed, the word "quantum" can be found in the formulation of the first law of thermodynamics by Mayer in his letter^[4] dated July 24, 1841. Max Planck used "quanta" to mean "quanta of matter and electricity",^[5] gas, and heat.^[6] In 1905, in response to Planck's work and the experimental work of Lenard (who explained his results by using the term "quanta of electricity"), Albert Einstein suggested that radiation existed in spatially localized packets which he called "quanta of light" ("Lightquanta").^[7]

The concept of quantization of radiation was discovered in 1900 by Max Planck, who had been trying to understand the emission of radiation from heated objects, known as black-body radiation. By assuming that energy can only be absorbed or released in tiny, differential, discrete packets he called "bundles" or "energy elements",^[8] Planck accounted for the fact that certain objects change colour when heated.^[9] On December 14, 1900, Planck reported his revolutionary findings to the German Physical Society, and introduced the idea of quantization for the first time as a part of his research on black-body radiation.^[10] As a result of his experiments, Planck deduced the numerical value of h, known as the Planck constant, and could also report a more precise value for the Avogadro–Loschmidt number, the number of real molecules in a mole and the unit of electrical charge, to the German Physical Society. After his theory was validated, Planck was awarded the Nobel Prize in Physics in 1918 for his discovery.

Beyond electromagnetic radiation

While quantization was first discovered in electromagnetic radiation, it describes a fundamental aspect of energy not just restricted to photons.^[11] In the attempt to bring experiment into agreement with theory, Max Planck postulated that electromagnetic energy is absorbed or emitted in discrete packets, or quanta.^[12]

References

^ Wiener, N. (1966). Differential Space, Quantum Systems, and Prediction. Cambridge: The Massachusetts Institute of Technology Press
^ E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
^ E. Helmholtz, Robert Mayer's Priorität [1] (German)
^ Herrmann,A. Weltreich der Physik, GNT-Verlag (1991) [2] (German)
^ Planck, M. (1901). "Ueber die Elementarquanta der Materie und der Elektricität". Annalen der Physik 309 (3): 564–566. Bibcode:1901AnP...309..564P. doi:10.1002/andp.19013090311. (German)
^ Planck, Max (1883). "Ueber das thermodynamische Gleichgewicht von Gasgemengen". Annalen der Physik 255 (6): 358. Bibcode:1883AnP...255..358P. doi:10.1002/andp.18832550612. (German)
^ Einstein, A. (1905). "Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt". Annalen der Physik 17 (6): 132–148. Bibcode:1905AnP...322..132E. doi:10.1002/andp.19053220607. (German). A partial English translation is available from Wikisource.
^ Max Planck (1901). "Ueber das Gesetz der Energieverteilung im Normalspectrum (On the Law of Distribution of Energy in the Normal Spectrum)". Annalen der Physik 309 (3): 553. Bibcode:1901AnP...309..553P. doi:10.1002/andp.19013090310. Archived from the original on 2008-04-18.
^ Brown, T., LeMay, H., Bursten, B. (2008). Chemistry: The Central Science Upper Saddle River, NJ: Pearson Education ISBN 0-13-600617-5
^ Klein, Martin J. (1961). "Max Planck and the beginnings of the quantum theory". Archive for History of Exact Sciences 1 (5): 459. doi:10.1007/BF00327765.
^ Melville, K. (2005, February 11). Real-World Quantum Effects Demonstrated
^ Modern Applied Physics-Tippens third edition; McGraw-Hill.

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1. 神経筋接合部の電気診断学的評価 electrodiagnostic evaluation of the neuromuscular junction

English Journal

On the replication of Kristofferson's (1980) quantal timing for duration discrimination: some learning but no quanta and not much of a Weber constant.

Matthews WJ, Grondin S.SourceDepartment of Psychology, University of Essex, Colchester, CO4 3SQ, United Kingdom, will@essex.ac.uk.
Attention, perception & psychophysics.Atten Percept Psychophys.2012 Jul;74(5):1056-72.
This study revisited Kristofferson's (Perception & Psychophysics 27:300-306, 1980) report showing that, with sufficient practice at interval discrimination, the relationship between timing variability and physical time is a step function-in other words, that psychological time is quantized. Two
PMID 22391892

HDAC activity is required for BDNF to increase quantal neurotransmitter release and dendritic spine density in CA1 pyramidal neurons.

Calfa G, Chapleau CA, Campbell S, Inoue T, Morse SJ, Lubin FD, Pozzo-Miller L.SourceDepartment of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
Hippocampus.Hippocampus.2012 Jul;22(7):1493-500. doi: 10.1002/hipo.20990. Epub 2011 Dec 7.
Molecular mechanisms involved in the strengthening and formation of synapses include the activation and repression of specific genes or subsets of genes by epigenetic modifications that do not alter the genetic code itself. Chromatin modifications mediated by histone acetylation have been shown to b
PMID 22161912

Japanese Journal

Quantal Response Equilibria in a Generalized Volunteer's Dilemma and Step-level Public Goods Games with Binary Decision

川越敏司,松八重泰輔,瀧澤弘和
IERCU Discussion Paper No.245, 2015-02
… We also examined the explanatory power of a widely accepted model with bounded rationality, the quantal response equilibrium (QRE), It is shown that the performance of the QRE model is better in explaining laboratory data. …
NAID 120005574624

Mixed quantal-semiquantal dynamics with stochastic particles for backreaction.

Ando Koji
The Journal of chemical physics 141(14), 2014-10-14
… A mixed quantal-semiquantal theory is presented in which the semiquantal squeezed-state wave packet describes the heavy degrees of freedom. … Starting from the mean-field equations of motion that are naturally derived from the time-dependent variational principle, we introduce the stochastic particle description for both the quantal and semiquantal parts in an aim to take into account the interparticle correlation, in particular the "quantum backreaction" beyond the mean-field approximation. …
NAID 120005512251

キュミュラント動力学：ゆらぎをあらわに取り扱う動力学理論

重田育照
Molecular Science 7(1), A0057, 2013
… The second-order quantal and classical cumulant dynamics have almost the same structure with proper initial conditions and more terms to describe friction for latter equations. …
NAID 130003369400