Quantum phases of dipolar rotors on two-dimensional lattices
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
From few to many-body physics with dipolar quantum gases: Long-range interactions in the ultracold
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
The quantum phase transitions of dipoles confined to the vertices of two dimensional (2D)
lattices of square and triangular geometry is studied using path integral ground state quantum
Monte Carlo (PIGS) [1], generalized to include rotational degrees of freedom [2]. We analyze the
phase diagram as a function of the strength of both the dipolar interaction and a transverse electric
field. The study reveals the existence of a class of orientational phases of quantum dipolar rotors
whose properties are determined by the ratios between the strength of the anisotropic dipole-
dipole interaction, the strength of the applied transverse field, and the rotational constant. For
the triangular lattice, the generic orientationally disordered phase found at zero and weak values
of both dipolar interaction strength and applied field, shows a transition to a phase characterized
by net polarization in the lattice plane as the strength of the dipole-dipole interaction is increased,
independent of the strength of the applied transverse field, in addition to the expected transition
to a transverse polarized phase as the electric field strength increases. The square lattice is also
found to exhibit a transition from a disordered phase to an ordered phase as the dipole-dipole
interaction strength is increased, as well as the expected transition to a transverse polarized phase
as the electric field strength increases. In contrast to the situation with a triangular lattice, on
square lattices the ordered phase at high dipole-dipole interaction strength possesses a striped
ordering. The properties of these quantum dipolar rotor phases are dominated by the anisotropy
of the interaction and provide useful models for developing quantum phases beyond the well-
known paradigms of spin Hamiltonian models, realizing in particular a novel physical realization
of a quantum rotor-like Hamiltonian that possesses an anisotropic long range interaction [3].