in the articles [8–10]. This correspondence is reached by introducing an effective slit’s half- width v$_{z}$ = Z/T . And the momentum of the particles is p$_{z}$ = mv$_{z}$ , where m is its mass. De Broglie relations set momentum p$_{z}$ and en- ergy E = p 2 $_{z}$/ 2 m of the particle in correspon- dence with its wave characteristics such as a wave vector k$_{z}$ = p$_{z}$/ ¯ h and a frequency ω = E/ ¯ h . In that case, a plane wave mentioned earlier can be written down as exp { i ωt − i k$_{z}$z } . Now, the Gaussian wave packet (19) can be supple- mented by this plane wave, that describes, in the paraxial approximation [12], spreading of in- cident wave along the axis z : where double b , a = 2 b , is adopted as a metric width of the slit. Now, let us also define the complex time-dependent spreading [9] This spreading consists of real and imaginary parts. The imaginary part, Δ x$_{1}$ = ¯ hτ/ 2 mσ , emergent in Eq (14), represents uncertainty of the particle position on the axis x . What is physical sense of this part? First, we rewrite the imaginary part in the following form m Δ x$_{1}$/τ = ¯ h/ 2 σ . Observe that Δ x$_{1}$/τ is an uncertainty, δv$_{x}$ , of a drift velocity of the particle along the axis x . Consequently, δp$_{x}$ = mδv$_{x}$ is the uncer- tainty of its momentum along the same axis. On the other hand, let the effective slit width 2 σ be uncertainty of the particle coordinate, δx = 2 σ at passing across the slit. As a result, we find δp$_{x}$δx = ¯ h . One can see, it is the Heisenberg uncertainty principle [7]. By replacing relevant expressions in Eq. (16) by the parameters (17) and (18) we get the Gaus- sian wave packet in the following form Here we have rewritten the square root of imag- inary unit as a factor exp { i 3 π/ 4 } = √ − i . Pay attention to Eq. (19), the time parame- ter T did not disappear fully, but it remained in the denominator. In fact, it means, that by removing the particle source to infinity, its inten- sity, ψ $^{†}$ψ , in the vicinity of the slit grating be- come weaker in T − 1 times. We will suppose, that a particle beam from the source is monochro- matic, i.e., velocities of all particles are equal to the same quantity v$_{z}$ . Given path length Z from the source to the slit grating, the velocity is ment can be considered on an N -slit grating sit- uated in a plane ( x, z ), as shown in Fig. 4. One can see, by comparing equation (20) with such a formula presented in [10], that with ex- ception of some details these formulas are equiv- alent. For example, presence of the constant phase 3 π/ 4 in Eq. (20) is not critical for further observation of interference effects. Essential dif- ferences are, however, observed in normalization factors. Namely, the term Since in the paraxial approximation τ = z/v$_{z}$ , then argument of the wave function contains z instead of τ . In this case, interference experi- 6 σ = b √ 2 = a 2 √ 2 , (17) σ$_{τ}$ = σ + i ¯ hτ 2 mσ . (18) ψ ( x$_{1}$, x$_{0}$, z ) = √ m 2 π ¯ hT √ σ σ$_{τ}$ × exp$^{{}$ − ( x$_{1}$ − x$_{0}$ ) 2 4 σσ$_{τ}$ } × exp { i ( ωt − k$_{z}$z + 3 π/ 4) } . (20) ψ ( x$_{1}$, x$_{0}$ ) = √ m 2 π ¯ hT √ σ σ$_{τ}$ · e i 3 π/ 4 × exp$^{{}$ − ( x$_{1}$ − x$_{0}$ ) 2 4 σσ$_{τ}$ } . (19) FIG. 4: Interference experiment in cylindrical geometry. Slit grating with n = 0 , 1 , · · · , N − 1 slits is situated in a plane ( x, y ). Radiation goes along axis z . A = √ mσ 2 π ¯ hT (21) 0 x z y 0 1 2 3 4 5 6