A. Trombettoni

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We study the dynamical phase diagram of a dilute Bose-Einstein condensate (BEC) trapped in a periodic potential. The dynamics is governed by a discrete nonlinear Schrödinger equation: intrinsically localized excitations, including discrete solitons and breathers, can be created even if the BEC's interatomic potential is repulsive. Furthermore, we analyze(More)
In many physical applications solitons propagate on supports whose topological properties may induce new and interesting effects. In this paper, we investigate the propagation of solitons on chains with a topological inhomogeneity generated by inserting a finite discrete network on a chain. For networks connected by a link to a single site of the chain, we(More)
We report on the direct observation of an oscillating atomic current in a one-dimensional array of Josephson junctions realized with an atomic Bose-Einstein condensate. The array is created by a laser standing wave, with the condensates trapped in the valleys of the periodic potential and weakly coupled by the interwell barriers. The coherence of multiple(More)
The dynamics of Bose-Einstein condensates trapped in a deep optical lattice is governed by a discrete nonlinear equation (DNL). Its degree of nonlinearity and the intersite hopping rates are retrieved from a nonlinear tight-binding approximation taking into account the effective dimensionality of each conden-sate. We derive analytically the Bloch and the(More)
We investigate the possibility that Bose-Einstein condensates (BECs), loaded on a 2D optical lattice, undergo-at finite temperature-a Berezinskii-Kosterlitz-Thouless (BKT) transition. We show that-in an experimentally attainable range of parameters-a planar lattice of BECs is described by the XY model at finite temperature. We demonstrate that the(More)
The standard experimental techniques usually adopted in the study of the behaviour of ultracold atoms in optical lattices involve extracting the atom density profile from absorption images of the atomic sample after trap release. Quantum mechanically this procedure is described by a generalized measure (POVM); interference patterns found in absorption(More)
We investigate the possibility that Bose-Einstein condensates loaded on a 2D optical lattice undergo-at finite temperature-a Berezinskii-Kosterlitz-Thouless (BKT) transition. We show that in an experimentally attainable range of parameters the system is described by the XY model at finite temperature. We demonstrate that the interference pattern of the(More)
We study soliton dynamics in a system of two linearly coupled discrete nonlinear Schrödinger equations, which describe the dynamics of a two-component Bose gas, coupled by an electromagnetic field, and confined in a strong optical lattice. When the nonlinear coupling strengths are equal, we use a unitary transformation to remove the linear coupling terms,(More)
New coherent states may be induced by pertinently engineering the topology of a network. As an example, we consider the properties of non-interacting bosons on a star network, which may be realized with a dilute atomic gas in a star-shaped deep optical lattice. The ground state is localized around the star center and it is macroscopically occupied below the(More)