“…It serves as the model for the Josephson oscillation (periodic change in occupations of the lattice sites) and the self-trapping (interactioninduced destruction of the inter-site tunneling) [1][2][3][4], semiclassical quantization of the many-body systems [5,6], highly correlated states like fragmented condensates and NOON state [7][8][9][10][11], and the excited state quantum phase transitions [12][13][14]. From the experimental viewpoint the BH dimer can be realized by using several platforms among which are cold atoms in a two-well optical potential [3,4,14], two coupled optical microcavities with Kerr nonlinearity [15,16], and two capacitively coupled transmons [17,18]. Notice that the last two systems do not conserve the number of particles and, thus, they should be described in the framework of the open or dissipative Bose-Hubbard model [19,20].…”