quantum


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quantum

Physics
a. the smallest quantity of some physical property, such as energy, that a system can possess according to the quantum theory
b. a particle with such a unit of energy

Quantum (physics)

A term characterizing an excitation in a wave or field, connoting fundamental particlelike properties such as energy or mass, momentum, and angular momentum for this excitation. In general, any field or wave equation that is quantized, including systems already treated in quantum mechanics that are second-quantized, leads to a particle interpretation for the excitations which are called quanta of the field. This term historically was first applied to indivisible amounts of electromagnetic, or light, energy usually referred to as photons. The photon, or quantum of the electromagnetic field, is a massless particle, best interpreted as such by quantizing Maxwell's equations. Analogously, the electron can be said to be the quantum of the Dirac field through second quantization of the Dirac equation, which also leads to the prediction of the existence of the positron as another quantum of this field with the same mass but with a charge opposite to that of the electron. In similar fashion, quantization of the gravitational field equations suggests the existence of the graviton. The pi meson or pion was theoretically predicted as the quantum of the nuclear force field. Another quantum is the quantized lattice vibration, or phonon, which can be interpreted as a quantized sound wave since it travels through a quantum solid or fluid, or through nuclear matter, in the same manner as sound goes through air.

The use of quantum as an adjective (quantum mechanics, quantum electrodynamics) implies that the particular subject is to be treated according to the modern rules that have evolved for quantized systems. See Elementary particle, Gravitation, Graviton, Maxwell's equations, Meson, Phonon, Photon, Quantum electrodynamics, Quantum field theory, Quantum mechanics

quantum

(kwon -tŭm) The minimum amount by which certain properties of a system, such as its energy or angular momentum, can change. The value of the property cannot therefore vary continuously but must change in steps: these steps are equal to or are integral multiples of the relevant quantum. This idea is the basis of quantum theory and quantum mechanics. The photon, for example, is a quantum of electromagnetic radiation.

quantum

[′kwän·təm]
(communications)
One of the subranges of possible values of a wave which is specified by quantization and represented by a particular value within the subrange.
(quantum mechanics)
For certain physical quantities, a unit such that the values of the quantity are restricted to integral multiples of this unit; for example, the quantum of angular momentum is Planck's constant divided by 2π.
An entity resulting from quantization of a field or wave, having particlelike properties such as energy, mass, momentum and angular momentum; for example, the photon is the quantum of an electromagnetic field, and the phonon is the quantum of a lattice vibration.

quantum

References in periodicals archive ?
In contrast to public- key cryptography protocols like Diffie-Hellman, RSA, and elliptic-curve cryptography, QKD systems leverage the fundamental properties of quantum mechanics using photons of light, not prime numbers, to physically transfer a shared secret between two entities.
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* The release of an upgraded simulator on the IBM Quantum Experience that can model circuits with up to 20 qubits.
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The QUESS satellite will help China perform unprecedented levels of experiments in quantum communication by sending entangled photons from the satellite to relay stations in China and Europe, which is separated by about 1,200 kilometers (746 miles).
"The quantum Fredkin gate can also be used to perform a direct comparison of two sets of qubits to determine whether they are the same or not," co-author Timothy Ralph from the University of Queensland, said in the statement.
Technavio expects the APAC region to witness huge demand for quantum dots for display applications as it is a hub of OEMs.
Quantum computers generate much excitement due to their ability to construct multiple simultaneous calculations of the same problem, a feat that would theoretically enable them to far surpass conventional computers in certain types of functions.
Quantum repeaters are a critical enabling technology for quantum networking.