A scheme for one-dimensional localization of a three-level atom is proposed by employing a modified technique for the formation of a standing-wave regime using two standing-wave fields. In the present system, precise position information of the atom can be achieved by measuring the population of the excited state, which can be efficiently controlled by the symmetric and the asymmetric superpositions of two standing-wave fields in the presence of constructive quantum interference. Our results highlight that, depending upon the effect of asymmetric superposition, the proposed scheme may provide a promising way to obtain various types of single-peak and double-peak localizations of the atom either in a one-wavelength range or in a half-wavelength range with appropriate values of the Rabi frequencies, detunings and spatial phase shifts of the coupling fields.

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A study on the variation in resonant tunneling lifetime (RTL) with the applied electric field is presented for the GaAs/AlxGa1−xAs periodic multibarrier systems (MBSs). The variation shows a contrasting behavior of lifetime for quasiresonant states situated at the miniband edge and those for well inside the miniband. For fields larger than 500 kV/m, the RTL corresponding to the midband state increases with the increase in electric field, whereas it decreases with the increase in field for the states near the miniband edges. The existence of the characteristic field and the characteristic lifetime that represent the synchronization of carrier velocity associated with all the quasiresonant states is an interesting outcome of the present theoretical investigation in ballistic transport of carriers through a MBS. This synchronization results in the maximum average escape rate through the system. It has also been shown that the characteristic field corresponds to the formation of localized partial Wannier–Stark ladder states in the miniband.

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