An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 100
quantum defect
  کاست ِ کو‌آنتومی   
kâst-e kuântomi

Fr.: défaut quantique   

Of an atomic energy level, the difference between the principal quantum number and the effective quantum number.

quantum; → defect.

quantum efficiency
  کارایی ِ کو‌آنتومی   
kârâi-ye kuântomi

Fr.: efficacité quantique   

In a detector, the ratio of the number of photoelectrons released to the number of incident photons at a specific wavelength.

quantum; → efficiency.

quantum electrodynamics (QED)
  برقاتوانیک ِ کو‌آنتومی   
barqâtavânik-e kuântomi

Fr.: électrodynamique quantique   

The → quantum field theory that describes the properties of → electromagnetic radiation and its interaction with electrically charged matter in the framework of → quantum theory.

quantum; → electrodynamics.

quantum entanglement
  هم‌گورش ِ کو‌آنتومی، هم‌پیچی ِ ~   
ham-gureš-e kuântomi, ham-pici-ye ~

Fr.: emmêlement quantique, intrication ~   

A quantum → phenomenon that occurs when two or more particles (→ photons or → atomic particles) that have a common origin remain linked together when they travel apart. A measurement of one of the particles determines not only its → quantum state but the quantum state of the other particle as well. A change in one is instantly reflected in the other. To use a familiar example, it is as if you have a pair of dice entangled in such a way that when you throw them the sum of the two is 7. Any time you cast them, if the first die shows 2, 5, 3, etc. the other will show 5, 2, 4, etc., respectively. Quantum entanglement is rooted in the → superposition principle. But, in contrast to → quantum coherence, the states in a superposition are the shared states of two entangled particles rather than those of the two split waves of a single particle. There are several ways for entangling atomic particles. Photons can be entangled using → cascade transitions, as was done by Alain Aspect and colleagues in the early 1980s (→ Aspect experiment). Calcium atoms are put into a highly-excited energy level where the electron is forbidden to return to the → ground state by emitting a single photon. As a result, the atoms → decay by emitting two photons which are entangled. Like quantum coherence, quantum entanglement plays an essential role in quantum technologies, such as quantum teleportation, quantum cryptography, and super dense coding. See also → EPR paradox.

quantum; → entanglement.

quantum field theory
  نگره‌ی ِ کو‌آنتومی ِ میدان   
negare-ye kuântomi-ye meydân

Fr.: théorie quantique des champs   

The quantum mechanical theory based on the assumption that the interactions between particles and fields are mediated by messenger particles. Accordingly, particles are → quanta of a field, just s photons are quanta of light. All fields display a granular structure in interaction. QFT is the framework in which quantum mechanics and → special relativity are successfully reconciled (→ Dirac equation). It forms the basis of today's particle physics.

quantum; → field; → theory.

quantum fluctuation
  افتاخیز ِ کو‌آنتومی   
oftâxiz-e kuântomi

Fr.: fluctuation quantique   

The temporary variation in a → quantum field due to the → uncertainty principle.

quantum; → fluctuation.

quantum gravity
  گرانی ِ کو‌آنتومی   
gerâni-ye kuântomi

Fr.: gravité quantique   

A theory of gravity, yet to be developed, that would properly include quantum mechanics. Because of the tensor nature of general relativity, it is not renormalizable as a field theory in perturbation from flat space. So far various attempts to quantize general relativity have been unsuccessful.

quantum; → gravity.

quantum information
  ازدایش ِ کو‌آنتومی   
azdâyeš-e kuântomi

Fr.: information quantique   

The science concerned with the transmission, storage, and processing of information using quantum mechanical systems. It exploits the notion of → quantum entanglement between systems and joins several fields of knowledge, mainly quantum physics, information, computation, and probability.

quantum; → information.

quantum jump
  جهش ِ کو‌آنتومی   
jaheš-e kuântomi

Fr.: saut quantique   

The transition of a quantum system from one stationary state to another, accompanied by absorption or emission of energy.

quantum; → jump.

quantum mechanical system
  راژمان ِ کو‌آنتوم مکانیکی   
râžmân-e kuântom mekâniki

Fr.: système mécanique quantique   

A → physical system that is specified by a → wave function.

quantum; → mechanical; → system.

quantum mechanics
  کو‌آنتوم مکانیک، مکانیک ِ کو‌آنتومی   
kuântom mekânik, mekânik-e kuântomi

Fr.: mécanique quantique   

A development of Newtonian mechanics based on the discrete character of energy (Planck 1900) and the wave motion of material particles (de Broglie 1924). It is relies on the consideration that energy state of a quantum mechanical system can be derived at a given instant by a function whose square of the modulus gives the probability distribution of the coordinates of the system. Quantum mechanics is essential for the treatment of all atomic processes. It holds also for ordinary large scale processes although in this case the deviations from Newtonian mechanics are negligible.

quantum; → mechanics.

quantum noise
  نوفه‌ی ِ کو‌آنتومی   
nufe-ye kuântomi

Fr.: bruit quantique   

A random variation of signal due to fluctuations in the average rate of incidence of quanta on a detector. Quantum noise is described by the → Poisson distribution. Same as → photon noise and → shot effect.

quantum; → noise.

quantum number
  عدد ِ کو‌آنتومی   
adad-e kuântomi (#)

Fr.: nombre quantique   

A number used in quantum mechanics, specifying the state of an electron bound in an atomic system. The quantum numbers are integers or half integers and specify the number of units of energy, momentum, spin, etc. possessed by an electron.

quantum; → number.

quantum of action
  کو‌آنتوم ِ ژیرش   
kuântom-e žireš

Fr.: quantum d'action   

Since → Planck's constant has the dimension of → energy × → time, its sometimes called the quantum of → action.

quantum; → action.

quantum phase transition (QPT)
  گذرش ِ فاز ِ کو‌آنتومی   
gozareš-e fâz-e kuântomi

Fr.: transition de phase quantique   

A phase transitions that occurs at zero temperature as a function of a non-thermal parameter like → pressure, → magnetic field, or → chemical composition. In contrast to ordinary → phase transitions, which are associated with passage through a critical temperature, quantum phase transitions are associated with → quantum fluctuations, a consequence of → Heisenberg's uncertainty principle. For example, see → Bose-Einstein condensation.

quantum; → phase; → transition.

quantum state
  استات ِ کو‌آنتومی   
estât-e kuântomi

Fr.: état quantique   

In → quantum mechanics, the state of a system as described by a set of → quantum numbers and represented by an → eigenfunction.

quantum; → state.

quantum theory
  نگره‌ی ِ کو‌آنتومی   
negare-ye kuântomi (#)

Fr.: théorie quantique   

The theoretical basis of modern physics which describes the behavior and interactions of elementary particles or energy states based on the assumptions that energy is subdivided into discrete amounts and that matter possesses wave properties. → quantum mechanics; → quantum field theory.

quantum; → theory.

quantum unitarity
  یکاییگی ِ کو‌آنتومی   
yekâyigi-ye kuântomi

Fr.: unitarité quantique   

A property in → quantum mechanics whereby in a quantum system the sum of all probabilities of all possible outcomes must be 1. Quantum unitarity makes the modulous of a → quantum state invariant with time.

quantum. → unitary.

quantum walk
  پویش ِ کو‌آنتومی   
puyeš-e kuântomi

Fr.: marche quantique   

A generalization of the classical concept of → random walk using quantum mechanical laws such as the → superposition principle and → interference of quantum amplitudes. In the classical version the particle moves in the position space with a certain probability. In contrast, in the quantum counterpart the particle moves by exploring multiple possible paths simultaneously with the amplitudes corresponding to the influence of different paths. The concept of quantum walk is studied in two standard forms: → continuous-time quantum walk and → discrete-time quantum walk. Quantum walk was first introduced by Aharonov et al. (1993, Phys. Rev. A, 48, 1687).

continuous; → walk.

quantum yield
  بازده ِ کو‌آنتومی   
bâzdeh-e kuântomi

Fr.: rendement quantique   

In photochemistry, the number of defined events which occur per photon absorbed by the system.

quantum; → theory.

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