The Poincare's period of particle oscillations between wells is obtained in a double{well potential.The dependencies of the oscillation period on transmission coecient and on distance between levels are obtained.The cases of squared potentials and some potentials having rounded o forms are considered speci cally.
In this paper, particle tunneling through a 1-dimensional double square potential barrier is considered under fluctuations of an observer’s frame of reference (OFR). The concept of duration density—the proportion of the duration of a measurement that a particle has a particular energy—is adopted to formulate the average transmission probability of a particle for two types of fluctuations in the OFR. For single-period square-wave fluctuations, the average transmission probability is found to oscillate with a period of π or 2π as a function of the energy of the particle; the period of the oscillations rapidly switches from one value to another as a result of extremely small changes in the wavenumber configuration. For single-period sawtooth-wave fluctuations, the period of the oscillations in the transmission probability gradually increases from π to 2π as the wavenumber configuration changes. It is concluded, therefore that the average transmission probability has the potential to provide information about the nature of the fluctuations in an OFR.
Abstract Controlling the tunneling of atoms of one species using a different atom species is a fundamental step in the development of a new class of atom quantum devices, where detection, motion control, and other functions over the atoms, can be achieved by exploiting the interaction between two different atomic species. Here, we theoretically study coherent oscillations of a non-self-interacting Bose–Einstein condensate (BEC) species in a triple-well potential controlled by a self-interacting species self-trapped in the central well of the potential. In this system, a blockade, due to the interspecies interaction, prevents atoms of the non-self-interacting species from populating the central well. Thus, for an initial population imbalance between the left- and right-hand wells of the non-self-interacting species, coherent BEC oscillations are induced between these two wells, resembling those of Rabi-like BEC oscillations in a double-well potential. The oscillation period is found to scale linearly with the number of self-trapped atoms as well as with the interspecies interaction strength. This behavior is corroborated by the quantum many-particle and the mean-field models of the system. We show that BEC oscillations can be described by using an effective bosonic Josephson junction with a tunneling amplitude that depends on the number of the self-trapped atoms in the central well. We also consider the effect of the self-trapped atom losses on the coherent oscillations. We show, by using quantum trajectories, that this type of losses leads to a dynamical change in the oscillation period of the non-self-interacting species, which in turn allows the number of self-trapped atoms lost from the system to be estimated.
For a model 1d asymmetric double-well potential we calculated so-called survival probability (i.e. the probability for a particle initially localised in one well to remain there). We use a semiclassical (WKB) solution of Schroedinger equation. It is shown that behaviour essentially depends on transition probability, and on dimensionless parameter which is a ratio of characteristic frequencies for low energy non-linear in-well oscillations and inter wells tunnelling. For the potential describing a finite motion (double-well) one has always a regular behaviour. For the small value of the parameter there is well defined resonance pairs of levels and the survival probability has coherent oscillations related to resonance splitting. However for the large value of the parameter no oscillations at all for the survival probability, and there is almost an exponential decay with the characteristic time determined by Fermi golden rule. In this case one may not restrict oneself to only resonance pair levels. The number of perturbed by tunnelling levels grows proportionally to the value of this parameter (by other words instead of isolated pairs there appear the resonance regions containing the sets of strongly coupled levels). In the region of intermediate values of the parameter one has a crossover between both limiting cases, namely the exponential decay with subsequent long period recurrent behaviour.