An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → quantum walk taking place entirely in the position space. Continuous-time quantum walk was introduced by E. Farhi & S. Gutmann (1998, Phys. Rev. A 58, 915).

→ continuous; → time; → quantum; → walk.

A → quantum walk involving a probabilistic → operator that changes the direction while leaving the position fixed, and a shift operator that changes the position. Discrete-time quantum walk was introduced by J. Watrous (2001, Journal of Computer and System Sciences 62, 376)

→ discrete; → time; → quantum; → walk.

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.

The trajectory consisting of a series of successive moves in which the direction and size of each move is randomly determined.

→ random; → walk.

The mathematical description of the interval (→ space-time separation) between → events ("points" in space-time) in a → homogeneous and → isotropic → Universe. It results from an exact solution of → Einstein's field equations of → general relativity. Under the assumptions, the Robertson-Walker interval is expressed by:
ds² = c²dt² - R²(t) [dr²/(1 - kr²) + r²dθ² + r²sin²θ dθ²)].
Same as Friedmann-Lemaître-Robertson-Walker metric. Compare → Minkowski metric.

Named after Howard Percy Robertson (1903-1961), American mathematician and physicist, and Arthur Geoffrey Walker (1909-2001), British mathematician and physicist, for their contributions to physics and physical cosmology; → metric.

1) To move along on foot at a moderate pace; advance by steps.
2a) An act or instance of walking.
2b) Physics: A moving of a particle among particles. → random walk; → quantum walk.

M.E. walken, from O.E. wealcan "to toss, roll;" cf. O.N. valka "to drag about," Dan. valke "to full," M.Du. walken "to knead, press, full," O.H.G. walchan "to knead," Ger. walken "to full."

Camidan "to walk (proudly)," variant gâmidan "to walk," gâm "step, pace" (related to âmadan "to come," → consequence); Mid.Pers. gâm "step, stride, pace;" O.Pers. gam- "to come; to go;" Av. gam- "to come; to go," jamaiti "goes;" cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE stem *g^wem- "to go, come."
Puyeš, verbal noun of puyidan "to walk, run, trot; wander," from Mid.Pers. pôy-, pwd- "to run;" cf. Gk. speudein "to hasten;" Lith. spudinti.