A one-dimensional (1D) Bose system with dipole-dipole repulsion is studied at zero temperature by means of a Quantum Monte Carlo method. It is shown that in the limit of small linear density the bosonic system of dipole moments acquires many properties of a system of non-interacting fermions. At larger linear densities a Variational Monte Carlo calculation suggests a crossover from a liquidlike to a solid-like state. The system is superfluid on the liquid-like side of the crossover and is normal in the deep on the solid-like side. Energy and structural functions are presented for a wide range of densities. Possible realizations of the model are 1D Bose atom systems with permanent dipoles or dipoles induced by static field or resonance radiation, or indirect excitons in coupled quantum wires, etc. We propose parameters of a possible experiment and discuss manifestations of the zero-temperature quantum crossover.Up until now Bose-Einstein condensation has been realized in many different atom and molecule species with short-range interactions. At low temperatures such an interaction can be described by a s-wave scattering length and is commonly approximated by a contact pseudopotential. In contrast, some recent work has focused on the realization of dipole condensates [1,2,3,4,5]. In these systems, the dipole-dipole interaction extends to much larger distances and significant differences in the properties (such as the phase diagram and correlation functions) are expected. Another appealing aspect of a system of dipole moments is the relative ease of tuning the effective strength of interactions [6] which makes the system highly controllable. Dipole particles are also considered to be a promising candidate for the implementation of quantum-computing schemes [7,8,9].On the theoretical side dipole condensates have been mainly studied on a semiclassical (Gross-Pitaevskii) [10] or Bogoliubov [11] level. A model Bose-Hubbard Hamiltonian has been used to describe a dipole gas in optical lattices and a rich phase diagram was found [5,12]. So far there have been no full quantum microscopic computations of the properties of a homogeneous system.Recently the Monte Carlo method was used to study helium and molecular hydrogen in nanotubes [13]. Such a geometry, which is effectively one dimensional, leads to completely different properties compared to a threedimensional sample.We consider N repulsive dipole moments of mass M located on a line. The Hamiltonian of such a system is given bŷWe keep in mind two different possible realizations: 1) Cold bosonic atoms, with induced or static dipole momenta, in a transverse trap so tight that excitations of the levels of the transverse confinement are not possible and the system is dynamically one-dimensional. The dipoles themselves can be either induced or permanent. In the case of dipoles induced by an electric field E the coupling has the form C dd = E 2 α 2 , where α is the static polarizability. For permanent magnetic dipoles aligned by an external magnetic field one has C dd = m 2 ...
