| 释义 |
quantum|ˈkwɒntəm|
Pl. quanta (rare except in senses 5 and 6), † quantums (sense 5 only).
[L., neut. of quantus how much, how great.]
1. a. Sum, amount; = quantity 2; spec. in Law, an amount, a sum (of money payable in damages, etc.).
1619Purchas Microcosmus xxxii. 302 To set The true Quantum, the true poize and price vpon himselfe. 1738Hist. Crt. Excheq. iii. 43 To vote in the first Place, that the King should be supplied; in the next Place, the Quantum of the Supply. 1791T. Newte Tour Eng. & Scot. 179 The momentum of bodies depends on the quantum of their velocity multiplied into that of their matter. 1818Cruise Digest (ed. 2) I. 427 If the union and accession of the two estates were the cause of the merger, the quantum of the thing granted would be the measure of that merger. 1898in Southern Reporter XXIII. 718/2 The quantum of damages as fixed by the lower court is, we think, too low. 1912Law Rep. (House of Lords Appeal Cases) 688 The quantum of damage is a question of fact, and the only guidance the law can give is to lay down general principles. 1945Tulane Law Rev. XIX. 626 In a large majority of jurisdictions the pecuniary condition of the defendant has no bearing on the quantum of compensatory damages awarded the plaintiff in an action for personal injuries. 1951Scots Law Times 11 Aug. 181/1 There can never be any binding precedents on quantum of damages because a sum reasonable in the circumstances of case A might be grossly unreasonable in case B. Ibid., Quantum must be considered afresh in every case having regard to the particular circumstances of that case. 1970Internat. & Compar. Law Q. XIX. 126 Strict liability with an unbreakable limit should confine litigation to questions of quantum. 1974Times 6 Feb. 7/1 The Court of Appeal dismissed an appeal on quantum of damages by Horizon Holidays Ltd.
b. = quantity 7.
1815W. H. Ireland Scribbleomania 33 His study has not been for quantum to strive, But with beauties to keep the attention alive.
2. = quantity 12.
1647H. More Song of Soul ii. i. ii. lv, Each quantum's infinite, straight will be said. 1678Cudworth Intell. Syst. i. v. 783 Though it be an Absolute Contradiction, for a Body, or Quantum, to be..All of it in every Part of that Space, which the Whole is in. 1877E. Caird Philos. Kant ii. xi. 442 All phenomena, as perceived, are extensive quanta.
3. One's share or portion.
1649Jer. Taylor Gt. Exemp. ii. xii. 94 Poverty is her portion, and her quantum is but food and raiment. 1724Swift Drapier's Lett. Wks. 1755 V. ii. 60 He will double his present quantum by stealth as soon as he can. 1818Bentham Ch. Eng. 421 A Parish, in which the quantum of this soul-saving Mammon rises as high as 12,000l. a year. 1897F. T. Bullen Cruise ‘Cachalot’ 167 Having completed our quantum of wood, water, and fresh provisions.
4. a. A (specified) amount. = quantity 8.
1789Belsham Ess. I. ii. 19 Is there not a sufficient quantum of distress and misfortune? 1829Carlyle Misc. (1857) II. 113 Some smaller quantum of earthly enjoyment. 1852Jerdan Autobiog. II. xii. 137 Imbued with a moderate quantum of worldly wisdom.
b. = quantity 8 c.
1735Berkeley Querist i. §215 Such a bank..was faulty in not limiting the quantum of bills. 1828J. Ballantyne Exam. Hum. Mind II. 69 The mind..has always a tendency to possess the same quantum of ideas. 1879E. R. Lankester Advancem. Sc. (1890) 14 A struggle among all those born for the possession of the small quantum of food.
5. Physics. A minimum amount of a physical quantity which can exist and by multiples of which changes in the quantity occur.
This use of quantum originated in Ger. in two classic papers by Planck and by Einstein. Planck introduced the concept of a quantum in Verh. d. Deutsch. Physik. Ges. (1900) II. 237ff. In that paper he assumed that the energy of an oscillator is always an integral multiple of an ‘energy element’ (G. energieelement, p. 242), i.e. a quantum (sense 5 a), but he did not call it a quantum; however he did use the word in a passing reference to the electronic charge (‘das Elementarquantum der Elektricität’, p. 245: = sense 5 b).
Einstein, in Ann. d. Physik (1905) XVII. 132ff., assumed that light is radiated in the form of what he called ‘energy quanta’ (G. energiequanta, p. 133: = sense 5 a).
The affinities of the following isolated use are not clear; it seems not to be related to Planck's use, and may derive rather from senses 1–4.
1902Ld. Kelvin in Phil. Mag. III. 257 According to the well-known doctrine of Aepinus,..positive and negative electrifications consist in excess above, and deficiency below, a natural quantum of a fluid, called the electric fluid, permeating among the atoms of ponderable matter. Ibid. 259 The neutralizing quantum of electrions [= ‘atoms of resinous electricity’] for any atom or group of atoms has exactly the same quantity of electricity of one kind as the atom or group of atoms has of electricity of the opposite kind. The quantum for any single atom may be one or two or three or any integral number, and need not be the same for all atoms... The differences of quality of the atoms of different substances may be partially due to the quantum-numbers of their electrions being different.
a. A discrete quantity of electromagnetic energy proportional in magnitude to the frequency of the radiation it represents.
1910Sci. Abstr. A. XIII. 556 The absorption of the corresponding light-quantum. 1913Rep. Brit. Assoc. Adv. Sci. 1912 407 Assuming that an oscillator can only emit definite, discontinuous quantums of energy, Planck showed that their magnitude is proportional to the frequency. 1913Phil. Mag. XXVI. 19 These calculations strongly suggest that an electron of great velocity in passing through an atom and colliding with the electrons bound will loose energy in distinct finite quanta. 1929D. H. Lawrence Pansies 28 Look then Where the father of all things swims in a mist of atoms Electrons and energies, quantums and relativities. 1934A. J. Mee Physical Chem. xix. 721 We can, in a few cases, induce fluorescence of shorter wavelength than that of the absorbed light, since the energy emitted is not only that of the absorbed quantum, but also that inherent in the system before the absorption. 1965Physical Rev. Lett. XV. 1013/1 He+ ions decaying spontaneously from the 3S state do so via the 2P levels in ∼ 1 × 10-8 seconds with the emission of a 1640Å quantum followed by a 303Å quantum. 1978Sci. Amer. June 69/2 Conversely, when the atom or molecule is de-excited, it drops back one full step or more and the energy difference is either radiated away as a quantum of electromagnetic energy or transferred directly, through a collision, to another atom or molecule.
b. An analogous discrete amount of any other physical quantity (as momentum, electric charge).
1914Chem. Abstr. VIII. 1050 (heading) Existence of quantities of electricity which are smaller than the charge of the elementary quantum or the electron. 1923H. L. Brose tr. Sommerfeld's Atomic Struct. & Spectral Lines iv. 199 We see that the rotator is to be quantised not in energy quanta but in quanta of moment of momentum... The moment of momentum must be a whole multiple of h/2π. 1931H. P. Robertson tr. Weyl's Theory of Groups i. 43 The constant of proportionality was equal to the quotient of the h obtained by Planck from black body radiation and the elementary quantum of electric charge e. 1958Nature 31 May 1524/1 (heading) Detection of single quanta of circulation in rotating helium II. 1969Sci. Jrnl. Jan. 87/2 There is a possibility that one day a minimum absolute quantum of length may also be found in the universe. 1973Sci. Amer. Jan. 88/3 Waves of elastic crystal vibrations generate quanta of sound called phonons.
c. More fully quantum of action. = Planck's constant.
1913Phil. Mag. XXVI. 2 Whatever the alteration in the laws of motion of the electrons may be, it seems necessary to introduce..a quantity foreign to the classical electrodynamics, i.e. Planck's constant, or as it often is called the elementary quantum of action. 1922Rep. Brit. Assoc. Adv. Sci. 1921 473 The essential feature of the [quantum] theory is the existence of a universal constant, the quantum h = 6·55 × 10-27 erg sec., which in some way..controls exchanges of energy. 1923B. Russell ABC of Atoms vi. 80 The quantity h, Planck's quantum, has been found to be involved in all the very minute phenomena that can be adequately studied. 1933Nature 25 Mar. 422/2 A causal description in the classical sense is possible only in such cases where the action involved is large compared with the quantum of action. 1956E. H. Hutten Lang. Mod. Physics v. 179 We can measure simultaneous values of both parameters only in such a way that the numerical product of their inaccuracies is, at best, equal to the quantum of action h.
d. fig.
1960R. W. Marks Dymaxion World of B. Fuller 10/1 Fuller regards all human experiences as energy events finite in extent. All experiments performed, books written, thoughts expressed, and structures completed, are finite energy events. Together they form a totality, a cornucopia of patterned quanta. 1962P. Strevens Papers in Lang. (1965) v. 67 Teaching takes place by quanta. Whether the teacher realizes it or not, he can teach only in steps, though these vary in size. 1969Daily Tel. (Colour Suppl.) 10 Jan. 32/2 Generalisations serve a purpose, but true understanding is made up of many discrete quanta. I can describe the Atlantic littoral thus and so; but I know it—thus: [etc.]. 1977Times 4 Aug. 8/6 A fine quantum of derring-do ranging from icy Sweden to a storm-threatened Scottish islet.
6. Physiol. Orig. a small voltage of which integral multiples go to make up the end-plate potential measured at a neuromuscular junction; hence, the unit quantity of acetylcholine corresponding to this, multiples of which are released to transmit a nerve impulse across the junction.
1952Fatt & Katz in Jrnl. Physiol. CXVII. 120 The experiment throws some new light on the action of calcium at the nerve-muscle junction: lack of calcium apparently reduces the e.p.p. in definite ‘quanta’. 1954del Castillo & Katz in Ibid. CXXIV. 560 It has been suggested that the end-plate potential (e.p.p.) at a single nerve-muscle junction is built up statistically of small all-or-none units... A convenient picture of how hundreds of such quanta..can build up an e.p.p. of, say, 70–80 mV is provided by the hypothesis that separate parcels of acetylcholine (ACh), released from discrete spots of the nerve endings, short-circuit the muscle membrane. Ibid. 574 Recent evidence indicating that ACh release occurs in discrete quanta. 1970J. W. Phillis Pharmacol. of Synapses ii. 17 In addition to being released by stimulation, individual quanta are released from the terminal spontaneously... At the neuromuscular junction, the number of quanta available for immediate release is probably of the order of 1000. 1978Nature 9 Feb. 561/1 Acetyl⁓choline..is released from stimulated nerve terminals in packets or quanta, each containing roughly 10,000 molecules.
7. a. attrib. and Comb. (in sense 5), as quantum energy, quantum hypothesis, quantum law, quantum physics (hence quantum physicist), quantum property; quantum advance = quantum leap; quantum chemistry, the branch of physical chemistry concerned with the explanation of chemical phenomena in terms of quantum mechanics; so quantum chemist, an expert or specialist in this; quantum-chemical a.; quantum chromodynamics [chromo-, after quantum electrodynamics], a quantum field theory in which the strong interaction is described in terms of an interaction between quarks that is mediated by gluons, both kinds of particle being assigned a quantum number called ‘colour’; abbrev. QCD; quantum condition, a condition resulting from, or forming part of, the application of quantum theory to a system; a condition that selects from the states allowed by classical physics those that are consistent with quantum theory; quantum defect, a number representing the degree to which an energy level of an atom with a single valence electron is displaced from the corresponding level of the hydrogen atom, being the amount by which the true principal quantum number of the level exceeds the effective value of the number; quantum dynamics = quantum mechanics; hence quantum-dynamical a.; quantum effect, a physical effect attributed to the existence of quanta; quantum efficiency, the proportion of incident photons that are effective in causing the decomposition of a molecule, the emission of a photoelectron, or similar photo-effect; quantum electrodynamics, the part of quantum field theory concerned with the electromagnetic field and its interaction with electrically charged particles; so quantum-electrodynamic, -dynamical adjs.; abbrev. QED; quantum electronics, the branch of physics concerned with the practical consequences of the quantization of energy states and their interaction with electromagnetic radiation; so quantum-electronic a.; quantum field theory, a field theory that incorporates quantum mechanics and the principles of the theory of relativity; quantum increase, a sudden large increase; cf. quantum jump; quantum jump, an abrupt transition between one stationary state of a quantized system and another, with the absorption or emission of a quantum; also transf., a sudden large increase or advance; quantum leap, a sudden large advance; cf. quantum jump; quantum level, an energy level in a quantized system; quantum liquid, a liquid that exhibits quantum effects on the macroscopic scale; quantum number, a number which enters into the expression for the value of some quantized property of a system (usu. a particle, atom, or molecule) and can assume only certain integral and sometimes half-integral values; also transf., the property so characterized; quantum orbit, an orbit (of an electron in an atom) defined by a set of quantum numbers; quantum solid, a solid that exhibits quantum effects on the macroscopic scale; quantum state, a state of physical (esp. atomic) system that is defined by a set of quantum numbers; a quantized state; quantum statistics, the statistics of the energy distribution of particles when the quantization of energy is taken into account; cf. Bose–Einstein statistics, Fermi–Dirac statistics; hence quantum-statistical a.; quantum transition = quantum jump (lit. sense); quantum yield = quantum efficiency. Also quantum mechanics, quantum theory.
1974Sci. Amer. June 105/3 When these inferences are taken together with the differences between the two material cultures..one is led to conclude that the Upper Paleolithic represents a *quantum advance in human cultural evolution.
1960McGraw-Hill Encycl. Sci. & Technol. XI. 145/2 The most useful of these methods, the variation method, has produced most of the important *quantum-chemical concepts.
Ibid. 146/1 The success of this method depends.. on the ability of the *quantum chemist to guess at trial functions which are good approximations and at the same time contain parameters in such a form that W can be minimized without undue labor. 1970Sci. Amer. Apr. 54/1 Since the introduction of the fundamental wave equation of quantum mechanics by Erwin Schrödinger in 1926, much of the work of quantum chemists has been focused on its solution for specific chemical systems.
1944H. Eyring et al. (title) *Quantum chemistry. 1963New Scientist 14 Mar. 582/3 After a rather long incubation period, the new subject of ‘quantum chemistry’ has got into its stride and is gaining rapidly in strength.
1975H. Fritzsch et al. in Phys. Lett. B. LIX. 256/1 A good name for this theory is *quantum chromodynamics (QCD). 1976Nature 12 Aug. 538/1 The ‘gauge field theories’ are underlying not only weak electromagnetic but perhaps also strong interactions (the new jargon here being quantum chromo⁓dynamics, or QCD, analogous to quantum electro⁓dynamics). 1979Sci. Amer. Aug. 157/2 No one has yet been able to derive the confinement of quarks from the underlying theory of quantum chromodynamics.
1923Physical Rev. XXII. 547 This variation principle includes formally in a single equation the results of classical dynamics and the Sommerfeld *quantum conditions. 1955O. Klein in W. Pauli Niels Bohr 99 The importance of transformation groups for the formulation of quantum conditions in field theories..has been strongly emphasized. 1974G. Reece tr. Hund's Hist. Quantum Theory vi. 89 The ‘stationary states’ were selected from the possible classical motions by ‘quantum conditions’ Ik = hnk.
1930Ruark & Urey Atoms, Molecules & Quanta vii. 194 The *quantum defect is a measure of the departure of the spectral term from the hydrogenic term having the same total quantum number. 1970G. K. Woodgate Elem. Atomic Struct. vi. 103 We consider the sequence iso⁓electronic with sodium... The ionization potentials for this sequence,..together with the quantum defect δ(s).. are given below.
1932Physical Rev. XL. 406 In solving the wave mechanical perturbation problem the distance between the interacting structures has been treated as a fixed parameter. Then *quantum dynamical reasoning has been abandoned, and the remainder of the problem has been solved by the method of classical statistics.
1927Proc. R. Soc. A. CXIII. 621 (heading) The physical interpretation of the *quantum dynamics. 1967Condon & Odishaw Handbk. Physics (ed. 2) vii. i. 3/1 These laws of quantum dynamics must involve the universal Planck constant..in an essential way; and the quantum laws must go over asymptotically into the classical laws, not involving h, as the scale of the phenomena is increased.
1914Chem. Abstr. VIII. 3141 E. detd. the at. ht. of highly compressed He at temps. from 18° to 32° abs... A small *quantum effect is apparent. 1946Physical Rev. LXIX. 195 (heading) Quantum effects in the interaction of electrons with high frequency fields and the transition to classical theory. 1975McGraw-Hill Yearbk. Sci. & Technol. 114/2 The interaction between two charged particles, classically treated, is given..by Maxwell's electrodynamic equations, if the particles are in relative motion. The inclusion of quantum effects has led to a more general theory, called quantum electrodynamics.
1926Trans. Faraday Soc. XXI. 453 In the photochemical isomeric change of maleic and fumaric acid, the *quantum efficiency was found to be much smaller than unity. 1940Glasstone Textbk. Physical Chem. xiii. 1135 According to the law of the photo⁓chemical equivalent one mol of absorbing substance should decompose for every 2·854 × 105/λ kg.-cal. of radiation absorbed... This relationship..permits the law to be tested experimentally. The results are expressed in terms of the quantum efficiency. 1978Nature 16 Mar. p. xiv/3 Two versions of the new EMI photo⁓multiplier tube..are available with..typical peak quantum efficiency of about 22%.
1965Physical Rev. Lett. XV. 1013 (heading) Measurement of the *quantum-electrodynamic level shift in the n = 3 state of (He4).
1956Physical Rev. CI. 1410 The *quantum-electro⁓dynamical fourth-order corrections for the intervals of the triplet fine structure of helium are calculated.
1927Proc. R. Soc. A. CXIV. 243 Hardly anything has been done up to the present on *quantum electrodynamics. 1955L. Rosenfeld in W. Pauli Niels Bohr 70 They questioned the logical consistency of quantum electro⁓dynamics by contending that the very concept of electro⁓magnetic field is not susceptible, in quantum theory, to any physical determination by means of measurements. The measurement of a field component requires determinations of the momentum of a charged test-body; and the reaction of the field radiated by the test-body in the course of these operations would..lead to a limitation of the accuracy of the field measurement, entirely at variance with the premises of the theory. 1971Sci. Amer. June 64/3 The laws of electricity and magnetism as they are now embodied in the equations of quantum electrodynamics represent the one and only area in physics where a single quantitative description has proved valid over the entire range of experiments for which it has been tested, from cosmic dimensions down to 10-15 centimeter.
1976B. Bova Multiple Man (1977) i. 11 The President..was protected by an invisible laser-activated shield... Fool-proof *quantum-electronic security.
1959Jrnl. Appl. Physics XXX. 956/1 An international conference on *Quantum Electronics—Resonance Phenomena will be held.. on September 14–16, 1959. The conference will consider basic problems in physics and electronics which are important to the increasing use of molecular and atomic resonance in masers, atomic clocks, and related devices. 1965Wireless World Aug. 386/2 The film..covers a wide range of applications including quantum electronics in transistors, lasers and masers. 1972Physics Bull. Sept. 562/1 Quantum electronics as a field of study dates from the use of stimulated emission for microwave amplification in 1954.
1921Discovery Sept. 227/2 When the *quantum energy of the exciting radiation exceeds this amount the whole K series [of X-rays] is excited.
1948Physical Rev. LXXIV. 224/1 (heading) On infinite field reactions in *quantum field theory. 1956H. Umezaw Quantum Field Theory i. 11 The present quantum field theory was formulated (Heisenberg and Pauli (1929)) by extending quantum mechanics so as to satisfy the relativity requirements and to treat the various transmutations [of particles into one another]. 1978Sci. Amer. Feb. 128/1 (caption) The creation and annihilation of particles and antiparticles is the characteristic process that distinguishes quantum field theories from ‘classical’ field theories such as Maxwell's or Einstein's.
1914Rep. Brit. Assoc. Adv. Sci. 1913 378 The quite definite result is obtained that..the exchange of energy between matter and ether must take place by finite jumps of amount..ε = hν. This is, of course, the hypothesis, spoken of briefly as the *quantum-hypothesis, which was first suggested by Planck. 1968F. L. Pilar Elem. Quantum Chem. i. 8 Planck's own feeling, which persisted for many years, was that the quantum hypothesis itself could have no basic significance but rather was an artificiality which would eventually be replaced with a more reasonable alternative.
1973Sci. Amer. May 8/2 Intellectual and other exchanges with China appear to be on the verge of a *quantum increase. 1974Daily Tel. (Colour Suppl.) 16 Aug. 17 Throughout this enormous area..people have been dying of diseases aggravated by malnutrition, just as they have died every year since man first inhabited the Sahel, but so far there has been no quantum increase in human mortality as a result of the lengthy drought.
1927N. V. Sidgwick Electronic Theory of Valency ii. 18 Bohr's theory is based on two fundamental postulates... The second..is that the electron radiates energy..only when it passes in a ‘*quantum jump’ from one of these stationary states to another of smaller energy. 1937E. C. Kemble Fund. Princ. Quantum Mech. viii. 290 The variation in the distribution function thus defined..is commonly interpreted as due to ‘quantum jumps’ from one energy level to the other caused by the radiation. 1955Sci. News Let. 19 Feb. 116/2 Radioactive fall-out is the ‘third quantum jump’ in the history of modern weapons. The first quantum jump, Dr. Lapp explained, was the A-bomb that shattered Hiroshima. 1961Flight LXXX. 907/1 On the subject of launch operations, Mr Debus claimed that a ‘quantum jump’ was necessary to meet the challenge of the lunar programme. 1966Guardian 1 Jan. 8/1 This new escalation (or ‘quantum jump’, to use the latest addition to the bewildering mixture of metaphors) would look better if it were preceded by another bombing pause. 1974G. Reece tr. Hund's Hist. Quantum Theory x. 129 While the emission and absorption of light seemed to be connected with a quantum jump, its dispersion did not. 1975Chinese Econ. Stud. VIII. iv. 52 In old China, the issue of legal tender reached astronomical figures, leading to galloping inflation and quantum jumps in prices.
1916Chem. Abstr. X. 1722 (heading) The *quantum law and the structure of the hydrogen atom. 1967Quantum law [see quantum dynamics].
1970New Scientist 3 Dec. 372/1 The ability of marine technology to take ‘*quantum’ leaps in innovation means that a laissez-faire approach to the ocean mineral resources can no longer be tolerated. 1973Daily Tel. (Colour Suppl.) 2 Nov. 27/2 Hovercraft, like many inventions of modern technology, are supposed to progress in quantum leaps. 1977New Yorker 13 June 108/2 The imperial Presidency did not begin with Richard Nixon although under him abuses of the office took a quantum leap.
1931G. Gamow Constitution of Atomic Nuclei iii. 63 Some elements have rather complicated γ-ray spectra, while others have only a few lines... These facts are evidently connected with the strength of the initial excitation and the relative position of the *quantum-levels in the different nuclei. 1960Chalmers & Quarrell Physical Examination of Metals (ed. 2) xvi. 751 Above the true quantum levels there are further, ‘empty’ levels, representing states in which nuclei may exist momentarily before disintegrating.
1950F. London Superfluids I. 1 The ‘superfluids’ or ‘*quantum liquids’ probably exhibit the most conspicuous phenomena of macroscopic physics which have not yet been integrated into molecular theory. 1967[see quantum solid below]. 1975Physics Bull. July 311/3 The electrons in a metal constitute a quantum liquid in this sense at all temperatures up to the melting temperature.
[1902Quantum-number: see sense 5 above] .1920,1922*Quantum number [see N I. 4 b]. 1926, etc. [see L 7 b]. 1939G. Herzberg Molecular Spectra & Molecular Struct. I. i. 15 The azimuthal quantum number l gives us therefore the orbital angular momentum of the electron in units h/2π. Ibid. 18 In a magnetic or electric field, a precession of the angular momentum of an atom takes place... While classically the precession could take place at any angle to the field direction, according to quantum theory, only those angles are possible for which the components of the angular momentum in the direction of the field have the discrete values ml(h/2π), where ml = l, (l - 1), (l - 2),.., - l... ml is called the magnetic quantum number of the electron. 1967W. R. Hindmarsh Atomic Spectra vi. 70 If the magnetic field is so strong that its interaction with the magnetic moment of the atom is much stronger than the spin-orbit interaction, the orbital and spin angular momenta are no longer even approximately conserved, so that L and S are not well-defined quantum numbers. 1968J. Bernstein Elementary Particles & their Currents xiii. 211 The strong interactions of the strange particles are characterized by a new conserved quantum number in addition to the isotopic spin. This quantum number is the ‘strangeness’, S, or, equivalently, the ‘hypercharge’ Y. 1976Sci. Amer. Jan. 45/1 Some quantum numbers, such as spin angular momentum and electric charge, are invariably conserved.
1923H. L. Brose tr. Sommerfeld's Atomic Struct. & Spectral Lines ii. 67 The quantum theory asserts that all these *quantum orbits are stationary states of motion, that is they are traversed without radiation being emitted. 1928Quantum orbit [see packet n. 1 h].
1946Mind LV. 161 The philosopher finds support in the *quantum physicist's principle of complementarity. 1964M. McLuhan Understanding Media (1967) vii. 73 Werner Heisenberg..is an example of the new quantum physicist whose over-all awareness of forms suggests to him that we would do well to stand aside from most of them.
1931H. Johnston tr. Planck's Universe in Light of Mod. Physics 22 The Principle of Relativity..has proved itself a reliable and eloquent guide in the new regions of *Quantum Physics. 1971Sci. Amer. Mar. 75 Quantum physics normally deals with natural phenomena on a submicroscopic scale. 1978Ibid. Dec. 128/3 Quantum physics predicts that captured electrons can have only discrete energies, corresponding to the atomic energy levels described above.
1927A. S. Eddington Stars & Atoms 68 The property here referred to (the *quantum property) is the deepest mystery of light. 1978Nature 16 Mar. 291/3 The quantum properties of electromagnetic radiation.
1967Sci. Amer. Aug. 85/2 Solid helium..is the only known example of a ‘*quantum solid’, just as liquid helium is the only known example of a ‘quantum liquid’.
1921Chem. Abstr. XV. 1843 Schottky discusses..the Nernst heat theorem from the point of view of the internal ‘*quantum state’ of the mols. composing the system under discussion. 1946[see polaron]. 1972Sci. Amer. Oct. 101/1 The individual nucleons move in discrete quantum states just as the electrons in the atom exist in discrete quantum states.
1958Physical Rev. CXI. 1460 (heading) *Quantum statistical theory of electron correlation.
1932Jrnl. Chem. Soc. 373 We shall..discuss the important conclusions which can be drawn from the interpretation of molecular spectra regarding the so-called *quantum statistics in their relation to the nuclei. 1935Pauling & Wilson Introd. Statistical Mech. viii. 219 The quantum statistics resulting from the acceptance of only antisymmetric wave functions is considerably different. 1972Physics Bull. Dec. 709/1 It is our great good fortune that the only two substances that remain liquid down to the absolute zero obey different statistics (3He: Fermi–Dirac, 4He: Bose–Einstein) and thus allow us to study the differing effects of quantum statistics on condensed matter.
1924Physical Rev. XXIV. 330 The term to be retained is..the combination overtone asymptotically connected to the particular *quantum transition under consideration. 1927Fisher & Hartree tr. Born's Mech. of Atom ii. 54 Quantum transitions can be caused by light and by molecular impacts.
1927Jrnl. Amer. Chem. Soc. XLIX. 2451 These new facts make possible a better conception of the mechanism of the photochemical decomposition of ammonia... Warburg measured the *quantum yield and found it to be 4 quanta per molecule for light of wave length 2025–2140 Å. 1971Jrnl. Appl. Physics XLII. 567/2 The quantum yield of the Ag–O–Cs cathode for visible light is less than 5 × 10-3 electron per photon.
b. Passing into adj. (cf. quantal a.).
1922Rep. Brit. Assoc. Adv. Sci. 1921 474 This suggests that many phenomena which at present are thought to be satisfactorily explained by dynamics are really quantum phenomena. 1924Physical Rev. XXIV. 340 This connection of the classical and quantum differential absorption we shall term the correspondence principle for absorption. 1951Ibid. LXXXII. 116/2 The quantum nature of the exchange of energy between free electrons and electromagnetic fields. 1967Sci. Amer. Aug. 85/2 Perhaps the most perplexing characteristic of solid helium..is the fact that in spite of its unique quantum nature solid helium behaves in so many respects as a purely classical, or nonquantum, solid. 1975Nature 20 Mar. 223/3 The book is concerned mainly with electro⁓dynamics (both classical and quantum).
▸ quantum bit n. (in a quantum computer) a physical system for storing information that is capable of existing in either of two quantum states or in a superposition of both (e.g. a spinning particle), and hence can represent two different binary values simultaneously; a unit of information held in this way; also called qubit.
1991G. Brassard & C. Crépeau in A. J. Menezes & S. A. Vanstone Adv. in Cryptology 49 The first *quantum bit commitment scheme ever proposed is due to Bennet and Brassard..(actually, the protocol they describe is only claimed to implement coin tossing, but it is obvious how to modify it in order to implement bit commitment). 1994Computing 28 July 38/6 To take advantage of any increase in information capacity, the messages would be encoded in particles in a range of quantum states, each having independent probabilities. These quantum bits—‘qubits’—should allow an increase in data compression in certain coding regimes. 1999Sci. Amer. Aug. 14/3 Some labs have even built working models of quantum bits..using ions trapped in special cavities or nuclear magnetic resonance techniques.
▸ quantum computer n. a computer in which quantum effects are significant; spec. a (hypothetical) computer in which information is represented in terms of the possible quantum states of a set of physical systems (such as spinning particles), and in which the existence of superposed states would allow operations to be performed on all possible values of a variable simultaneously.
1982Internat. Jrnl. Theoret. Physics 21 474 Let the computer itself be built of quantum mechanical elements which obey quantum mechanical laws... A new kind of computer—a *quantum computer. 1985Proc. Royal Soc. (A.) 40097 Computing machines resembling the universal quantum computer could, in principle, be built and would have many remarkable properties not reproducible by any Turing machine. 1998Pop. Sci. Mar. 67/3 (caption) A team at Los Alamos National Laboratory is working on a prototype quantum computer using an ‘ion trap’ device in which the electrons of suspended calcium ions are acted upon by lasers. |